HomeMy WebLinkAboutAPA2979Alasha Habitat lldanagement Guide
Southcentral Region
Volume I:
Life Histories and
Habitat Requirements
of Fish andWildlife
Produced by
State of Alasha Department of Fish and Crame
Division of Habitat
Iuneau, Alasha
1985
o1e85 tl#''* & GAME
AIASKA DEPARTMEN]
contents
Achnovledgements
Introduction
Mammals
Marine Marmal s
---HETboF
seal 17
Steller sea lion 25
Sea otter 33
Terrestrial Marnmalsffiiteddeer 47
Caribou 67
Dal I sheeP 77
Moose 87
Birds
Bald Eagle 101
Dabbl ing ducks 113
Diving ducks L25
Geese 135
Seabirds I47
Trumpeter swan 157
Fish
Freshwater/Anadromous Fi sh en 167
Arctic arayl ing 183
Burbot 201
Lake trout 213
Rainbow trout/steel head 223
Sal mon
Chinook ?41
Coho 257
Chum 273
Pink 289
Sockeye 303
Mari ne Fi sh
--Effic cod 319
Pacific hal ibut 327
Pacific herring 333
Pacific ocean perch 345
Sabl efi sh 353
Wal l eye po'l l ock 361
Yelloweye rockfish 37L
ta
Shel I fi shTraEs
Dungeness 379
King 387
Tanner 401
Razor clam 415
Shrimp 42L
Volume z contains narratives on the distribution, abundance, and human trseof
selected species of fish and wildlife.
Maps
Introducti onffesixregionsoftheAlaskaHabitatMana9ement.Guides52. The four subregions of the Southcentral Region 10
3. The Southcentral Region 13
Life Histories and Habitat Requirements
aP of the sPecies' range (maP 1 of
each narrative).
Dabbl inq ducks
of dabbling ducks
coastal marshes of 1162. Major
113
UCI
Introducti on
--T. Tpes of
Management
Dabbl i n
Geese
1.
2.
3.
4.
Seabi rds
-T.
Figtlres
narrati ves and maps
Guides Proiect 6
produced by the Alaska Habitat
Tlables
DTil compos'ition of 6? dabbl ing
de'lta, Sept.-0ct. 1981 119
Breeding biology of dabbling ducks
PTant and animal species utilized by diving ducks
Reproductive characteristics of diving ducks 130
Preferred foods and breed'ing habitat of geese in
Region 138
Prdferred foods and breeding habitat of geese
Region 139
lleiti ng , reari ng, and mol ti ng bi ol ogy of geese 'in
Region 141
Neiting, rearing, and molting biology of geese
Region 142
Seabi rd I i fe hi stories 150
ducks on the west CoPPer River
l2r
r28
the Southcentral
i n the Southwest
the Southcentra'l
in the Southwest
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Achnowledgements
This project is under the direction of the Conmissioner of the Department of
Fish and Game, Don l,{. Collinsworth, the Director of the Division of Habitat,
Norman Cohen, and the Deputy Director, Bruce H. Baker.
Many individua'ls have been involved in the production of this second Alaska
Habitat Management Guide. All narratives were reviewed first by project
staff and distributed for both technical and departmental reviews. The
names of reviewers and other contributors are compiled in appendix A in
volume 2.
The fol'lowing lists the production team and the portion of the guide for
which authors are responsible.*
Marianne G. See, Coordinator
Bob Durr, Editor
Lana C. Shea, Team Leader, Wildlife Group Leader
Wayne Do'lezal , Fisheries Group Leader
Authors: l.lildlife
Steve Albert, Habitat Biologist: Sitka black-tailed deer LH (wjth M.
Sjgman), DA; Bald Eagle DA; sea lion DA; harbor seal DA; sea otter DA;
caribou DA, HU-H.
Mike McDonald, Game Bio'logist: harbor seal LH; caribou LH; moose LH (with
F. Nelson), DA, HU-H.
Masters, Habitat Biologist:
Mooring, Habitat Biologist:J. Westl und).
Sitka black-tajled deer HU-H; furbearers
dabbling and diving ducks and geese LHs
F. Nelson, Game Biologist: trumpeter swan LH (with R. Mooring), DA; Bald
Eag'le LH.
John Westlund, Game Biologist: dabbling and diving ducks and geese LHs
(with R. Mooring), DA, HU-H; seabirds LH (with F. Nelson); sea 'lion LH; sea
otter LH (with F. Nelson); Dall sheep LH, DA, HU-H.
* LH=life history and habitat requirements; DA=distribution and abundance;
HU-C=human use-commercial fishing; HU-T=human use-trapping; HU-H=human use-
hunting; HU-P=human use-personal use/subsistence fishing; HU-S=human use-
sportfi shi ng.
Mi ke
HU-T.
Robi n
(wi th
Authors: Fish
Wayne Dolezal, Fisheries Bio.logist: chinook, coho, sockeye, chum, and pink
salmon LH, DA (with M. Rowse).
Katherine A. Rowell, Fisheries Biologist: Pacifjc herring LH, HU-C; king
crab LH, HU-C; Dungeness crab LH, HU-C.(with D. Sigurdsson);.Tanner crab LH,
HU-C; s'hrimp LH, FU-C (with M. Rowse); chinook, coho, sockeye, chum, and
pink salmon HU-C.
Melinda L. Rowse, Fisheries Biologist: chinook, coho, sockeye, chum, and
pink salmon DA (wittr lrl. Do]eza1 ); ihrimp HU-c (with K' Rowell)'
Dora Sigurdsson, Fisheries Technician: Dungeness crab HU-C (with K.
Rowel I ) .
Sandra K. Sonnichsen, Fisheries Biologist: Pacific halibut LH, DA, HU-C,
HU-S; Pacific cod LH, DA, HU-C; sablefish LH, DA, HU-C; yel-loryeyq rockfish
LH, bA, HU-C, HU-S; groundfish HU-C; razor clam LH, DA, Hu-C, HU-P; rainbow
irout/iteelhead fH, On, HU-S; arctic char/Do11y Varden LH (w_ith K. Webster),
DA, HU-S; arctic arayling LH (with K. Webster), DA, HU-S; lake trout HU-S;
salmon HU-S; burbot HU-S.
Kathleen R. Thornburgh, Habitat Biologist: lake trout DA; burbot LH, DA;
Pacjfic herring DA; king crab DA; Dungeness .crab DA; Tanner crab DA; shrimp
DA; salmon HU-P; shellfish (crabs and shrimp) HU-p.
Keith A. Webster, Fisheries Biologist: arctic char LH (with S. Sonnichsen);
arctic grayling LH (with S. Sonnichsen); lake trout LH.
Authors: Subsistence and 0ther Local Use of Resources
Dave Andersen, F'ish and Game Resource Special'ist: Upper Cook Inlet/Susitna
Basin Subregion.
Rob Bosworth, Fi sh and Game Resource Speci al i st:
Basjn/Wrange11 Mountajns and Lower Cook Inlet/Kenai Peninsula
Bob Schroeder, Fish and Game Resource Special'ist:
Subregi on .
Support staff
Lauren Barker, Ljbrarian
Carol Barnhill, CartograPher
Tom Bucceri, CartograPher
Patti Frink, Drafting Technic'ian
Mi chael Frost, Draf ti ng Techn'ici an
Susan H. Grainger, Clerk/TYPist
Juanita R. Henderson, Clerk/Typist
Pri nce
Copper Ri ver
Subregi ons .
tJilliam Sound
vi
Frances Inoue, Drafting Technician
Clare A. Johnson, Clerk/Typist
Ethel Lewis, Clerk/Typist
Greg Mi l'ls , Analyst/Programmer
Laura Nowell, Clerk/Typist
Cynthia Pappas, Drafting Technician
Cheryl Pretzel, Clerk/Typist
Gay Pu'l1ey, Graphic Artist
Lavonne Rhyneer, Drafting Technician
Don Shields, Drafting Technician
The process of developing the initial plan and procedtryes for this proiect
invoived a number of individuals who are not otherwise listed as authors and
contributors. These include many staff within the Division of Habitat, as
wel I as p1 anners and research . and management coordi nators of other
di vi s'ions . Thi s group a1 so i ncl udils al 1 project team members and a'l I ADF&G
regional supervisors. Special mention should be made of the support frgm
Cail Yanagawa, Regional Supervisor of the Division of Habitat for the
Southcentra'l Region (Region II), and of the contributions of Rai Behnert,
who was the original coordinator of this project. |.le would also like to
acknowledge the many contributions of John A. Clark, who was Director of the
Division of Habitat until his untimely death earlier this year.
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Introduction
Overvietv of Habitat Management Guides Proiect
Background
Alaska js an immense and bountiful frontjer, and until iust recently it was
all but inconceivable that we would ever need to worry about its capacity to
sustain the wealth of fish and wildlife resources for which it is renowned.
But the impetus of progress has not abated, and the pressure t9 de_ve1op our
lands and waters intensifies dai'ly. Every year more lands in Alaska are
being proposed for uses other than as wildlife habitat, especia'lly around
citi6s, towns, and vi'l1ages. These proposed uses include logg'ing, mining'
hydroeiectric projects, agriculture, settlement, geothermal -development, and
oit and gas lease!, among others. As the number of proposals and plans for
devel opmdnt conti nues to i ncrease , so does the need to careful 'ly and
efficibntly eva'luate their possible effects upon species and hab.itats and to
recommend vlaUte managerial.options to guarantee that our valuable fish and
wildlife resources and habitats are adequate'ly protected and maintained. By
using appropriate planning and managerial techniques most of the potential
for damage and loss of access for human use can be avoided.
One of the responsibilities of the Alaska Department of Fish and Game
(ADF&G) is to assist land managers by recommending to them the best ways and
means, based upon the best available data, for protecting local fish'
wildlife, and habitats against adverse effects and impacts. Because many
proposal s and p1 ans for d-evel opment and I and uses req_ui re a -r_api
d response
?roin the department, there may not be enough time for staff to actually
study the specific area in which the proposed development js to occur.
However, the department still needs to accumulate and assess a wide variety
of information jn order to prepare recommendations for manag'ing habjtat.
Therefore, the department initiated the Alaska Habitat Management Guides
(AHMG) project to prepare reports of the kinds of informat'ion upon which its
recommendations must be founded in order to responsibly and rapidly address
land and water use proposals made by land managers. These guides are a
major undertaking and will be of inestimable value to the state in its
efiorts to avoid- or mitigate adverse impacts to Alaska's great wealth of
fi sh and wi I dl i fe.
Purpose
This project presents the best available information on selected fish and
wildlife species: mapping and discussing their geographical djstribution;
assessing 'their relative-abundance; describing their life functions and
habitat requirements; identify'ing the human uses made of them, inc'luding
harvest patterns of rural communities; and describing their role in the
state's economy. This last kind of jnformation, because of the variety of
values humans place upon fish and wildlife, is not easily derived. There
are, howeverr'several' methods to estimate some of the economic values
asi6ciateO wiih these resources, and such estimates have become particularly
important i n 'l and use p1 anni ng because many potenti a1 'ly conf I i cti ng uses
must be evaluated in economic terms.
Essential to assessing what might happen to fish and wildlife if their habi-
tats are altered is i-nformation about what effects or impacts are typica'l]y
associated with particular kinds of developmental activities. The habitat
management guidei therefore also provide summaries of these known effects.
This- informition, in conjunction with compi'led life history information'
will allow those concerned to estimate how sensitive a given species might
be to a specific proposed activ'ity - whether or not, and to what degree' the
iisfr ind' wildl ife ' are 1 iable to be impacted. The guidance offered
(a-compllation of existing opt'ions for habitat _management) is not site-
ipecific. Rather, it is gbneial information available to those who seek to
avoid adverse impicts without p'lacing undue restraints upon other land and
water uses.
The completed guides coverage of fish and wildlife resources encompasses.the
Fish an'd Game hesource Management Regions established by the Jojnt Board of
Fisheries and Game (map 1). These regions provide the most inclusive and
consistent format for'presenting information about fish and wildlife re-
sources and relat'ing'it to management activities and data collection efforts
within the department.
Appl i cati ons
The choice of the term "guides" rather than "plans" for the reports is
consistent with the largely advisory role of the department with respect to
land management issues.- itre guides wi'll provide the department as well as
other stale, federa'|, and private 'land managers with information necessary
for the development of land and water use p'lans. Thus, the guide-s t!gt-
se'lves are not land management plans and do not provide for the allocation
or enhancement of fish and witAtite. Information included in a guide will
be used by the department's staff in their involvement jn the land use
p'lanning endeavors bf various land managers. For specific land use planning
bttortsl the department joins with other agencies to reconmend particular
uses of A'laska's lands and waters, as for example in plans by the Department
of Natural Resources (Susitna Area P'lan, Tanana Basin Area P1an, Southeast
Tide'lands Area Plan). The public, by means of the public review that is an
integra'l part of land managjement agencies' p'lanning. processe_s_,_ then has an
oppoitun'ity to evaluate any recornmendations made by the ADF&G that are
incorporated by the land-managing agency.
The guides have been designed to provide users with interrelated subiect
areai that can be appf ied -to specific questions regarding habitat_ manage-
ment. Each type of data will be presented in a separate volume, as
indicated in figure 1. Material from the project's database can be used,
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for example, to correlate information on species' seasonal and..geographic
habitat irse with the written and mapped information on known distribution
and abundance. The narratives and maps regard'ing human uses of fish and
wildlife can be compared with abundance and distribution information to
obtain an indication of the overall regional patterns of distribution'
abundance, and human use for the species of interest. Thg specific
information on habitat requirements also will relate direct'ly to the
jnformation on impacts associated with land and water use. This in turn
will form the basi's for the development of habitat management guidance.
An additional purpose of this project js to identify gaps in the. information
avai lable on 'species, human
'uses, and assoc jated .impacts. . A _ particular
species, for eiamp'le, may be known to use certain habitats during certain
seasons; yet informatioir on the timing of these use- patterns- may- be
inadequite. In general, there is little documentation of_impacts from land
and water uses oi species' habitats and on the human use of those speg]ql.qr
on the economic values associated with the use of fish and wildl'ife
res0urces.
To ma'intain their usefulness these habitat management guides are designed to
be periodical'ly updated as new research and habitat management options ale
reported to til'l 'data gaps. Users of these guides are advi sed to consul t
witfr tfre appropriate splcies experts and area b'iologists, however, to check
on the availability of more recent information.
Statewide Guides Volumes
The guides reports on impacts and guidance are_ being developed as statewide
voluiles, in which information is presented for statewide as well as for
specific regional concerns. The statewide volume on impacts. will sunmarize
the effects of major types of development activities and land and water uses
on fish and witOtite, their habitats, and their use by people. The
activities discussed will be those actually occurring in the state 0r
expected to occur in the future. This survey of impacts "i]] be founded
upbn the most recent pertinent literature and upon the information presented
ih ttre species life histories and habitat requirements. The guidance volume
will in turn be a synthesis of information based upon the impacts literature
and the ljfe history and habitat requirements information.
The fo1 'lowi ng uses of I and and water resources qrld lypes of . devel.opment
occur or are i'ikety to occur in Alaska, and they wi1'l therefore be addressed
in the statewide impacts and guidance volumes:
o 0i I and gas deve'lopment
" Harbors and shoreline structures
o Water devel opment
Placer mining
Strip and open pit mining
Underground mining
Seafood process'ing
Logging and timber processing
Transportation - road, rai'l , air
Transmission corridors
Grain and hay farm'ing
Pi pel i nes
Geothermal energy development
Settl ement
" Fire management
" 0ffshore prospecting and mining
" Commercial fishing
A statewide volume is being developed to provide an overview of the regional
economies, especially in iegards to uses of fish and wildlife within each
region. The hecessaiy data on the fish and wildlife related sector will be
by no means complete but will neverthe'less afford a conservative estimate of
silch values wjthin the regions. Economic data on cornmercia] fisheries, for
examp'le, are relatjve'ly we1'l documented. In thos-e _regions. wt!h.- !igni!!gult
commercial fishing activity, the relative va1ue of fish and wi'ldlife will be
better represented. However, continuing effort_ is be_ing made by the depart-
ment and'other agencies to improve the capabi'lity of accurately describing
the socioeconomiCimportance of fish and wildlife to the people both within
and outside the State of Alaska.
A separate statewide volume describing the I ife history and habitat
requii^ements of selected fish and wildlife species js being.prepared region
by'regioni therefore the information in the Southcentral g_uide addresses the
s-peci6s requirements in the Southwest and Southcentral regions. Other
ihformation'will be added as reports are prepared for the remaining regions.
Southcentral Region
Organization and Use of the Guide
Narratives. The two narrative volumes of the guide to the Southcentral
FegiA-f,r; closely related and interde-pendent. The first high'liglls
imfortant aspects of se'lected species l.ife histories, ellPhas'izing, the
inlerrelationihips of the species with their habitats. The second, oF
distribution and human use v'olume, provides the most current estimates of
ipecies' distribution and relative abundance and delineates the r_egional anq
iuUregionat patterns, locations, and types of human uses of fish and
wj'ldlife resources. This portion of the -guide provides an understan4ing 9f
the importance of fish and wildlife to itre people within and outside the
Southcentral Region.
The life histories include information for both the Southwest and South-
central regions, as mentioned in the preceding overview section. For one
species (Sltka black-tailed deer) we have also included habitat requirements
fbr Southeast Alaska. The reason for the inclusion is that the most
pertinent information has been collected from the Southeast Region and is
iarge'ly applicable as wel'l to the Southwest and Southcentral regions.
Because of the wide spectrum of human uses of fish and wildlife' this
oortion of the secona vdlume is divided into five topical categories. These
include 1) hunting and trapping, 2) commercial fishing,_ 3) _sportfishing,
4) personal use hlrvest, and 5) subs'istence and other I ocal uses. For
citbgories 1 through 4, data are presented by selected species, and the
information pertains to the entire region and the specific management.areas
within the region, as appropriate. All reports by species are based uPo!
data collectei bi the "Divjsions of Game, Sport Fish, _and Commercial
Fisherjes, as weli as by the Conrnercial Fisherjes Entry Conrmission, the
International Pacific Halibut Commission, North Pacifjc Fisheries Management
Council, and the National Marine Fisheries Service.
For the fjfth category of human use information, the Southcentral Region has
been divided into iour subregions (map 2) to portray community use patterns
of local fish and wildlife iesources. These subregions are 1) Upper Cook
Inlet/Susitna Basin, 2) Lower Cook Inlet/Kenai Peninsula, 3) Copper River
Basin/Wrangell Mountains, and 4) Prince William Sound. The patterns of use
described in these narrltives are based primarily upon community studies
coordinated by the Division of Subsjstence,'with additional source materials
from other anthropological studies on the history and patterns of activity
in the subregions.
Maps. A major portion of the guides proiect in the Southcentral Region was
cffiitted to thi production of -updated fish and wildl jfe maps at two scales
of resolution. 'species distributions and human use were mapped -at q
reference scale of 1:250,000 and then were mapped at the index scale of
1:1,0001000. Some reference maps for marine species were actually prepared
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at the 1:1,000,000-sca1e because that is the most appropriate scale to
portray the level of detail of data on thos_e species distributions.
itefereirce maps are bei ng reproduced as b'l ue-l i ne copi es coryqile! i n
.ititogu.t that are availiUte 'at ADF&G offices of the reg'ion. Additional
copies"will be available for other users, at cost of reproduc_tjon, from our
contract vendor. These maps can quite easi'ly be updated. The index maps
are being printed in color and will be jncluded in atlases.
For the Southcentral Reg'ion, there are approx'imate'ly 421 reference maps that
depict fish and shellfish species distribution, wil_dl_ife species distribu-
iibn, community or subsistehce use of fish and wildlife, and corunercia'1,
recreational , fersonal, and genera'l use of fish and wildl'ife.
Species Selection Criteria
Each specjes covered in the guides was selected because it met the fol'lowing
criteria: 1) its habitat is representative of some portion of the spectrum
of the Southtentral Region's habitats (tnis crjterion ensures that regional
habitats are well represented);2) it const'itutes an important resource to
human users in the region;3) the spec'ies or its habitat is liable to be
alversely affected bi present or proposed I and or water uses; and
4) adequite information on its life history, abundance, and djstrfbution was
available.
Based on the above criteria and the prioritjzed requests of each division'
the species Iist for the Southcentral Reg'ion was developgd.to include 30
inOiviauat species, plus species groups, includi.ng.seabirds (25),.dabbling
unJ Oiutng ducks (tg), geise (tOi, furbearers (tt), and shrimp (5). The
indjvidual species are as follows:
Hal i but
Pacific cod
Pacific ocean perch
Sabl efi sh
Wa'l 'leye po1 l ock
Yellowfin sole
Pacific herring
Dungeness crab
King cnab
Tanner crab
Razor clam
Many other species, including but not limited to the fo11owi1g,.dfe also
imp-ortant to consiie cisions or
p1 ans :
Sea otter
Harbor seal
Steller sea lion
Sitka black-tailed deer
Cari bou
Moose
Dal I sheep
Bald Eagle
Trumpeter swan
Arctic grayl ing
Arctic char/Dol]y Varden
Rainbow/steel head trout
Lake trout
Burbot
Sockeye salmon
Pink salmon
Chum salmon
Chinook salmon
Coho salmon
Brown bear
Mountain goat
Beaver
Bl ack bear
Wol f
Lynx
Northern pike
Whitefish
Cutthroat trout
11
Land otter
Mi nk
Minke whale
Fi n wha'le
Dall porpoise
Peregrine falcon
Ptarmi gan
Marten
Humpback whale
Belukha whale
Killer whale
Harbor porpoi se
0s prey
Grouse
Eul achon
Li ngcod
Hardshel I cl ams
Starry flounder
Sand I ance
Stickleback
Scul pi n
Overview of the Southcentral Region
The Southcentral Region (map 3) includes the Chugach, Talkeetna, l"lrangel1
and Kenai mountains-and the'southern slopes of the Alaska Range. A few of
the larger river basins in the region include the drainages of the Susitna'
Belugar-Chakachatna, Big, Crescent, Kasi'lof, Kenai, Matanuska, Copper' .anqBeriig rivers. Marine waters associated with the region afe comprised of
the n6rthern Gulf of Alaska, Cook Inlet, and Prince Wjl'liam Sound.
In the following sections, the biophysical, bjotic, and human resources of
the region are -briefly summarized. Readers desiring a Inore.detailed and
extensi-ve discussion of thesq characteristics of the reg'ion should consult
the Alaska Regional Profiles. ^
Biophysical Features
Portions of the Southcentral Region are in the maritime, transitional, and
contjnental climatic zones. The weather in the region is the result of the
interaction between land topography and major weather systems that move
northward across the Gulf of Alaska or eastward across the Bering Sea.
Prince 111illiam Sound, the southern Kenai Peninsu'la, and the southwest side
of'lower Cook Inlet are characterized by a fiord-like coastline rising to
mountains up to L2,000 feet. The northwest side of the Kenai Peninsula and
lower Cook' Inlet and all of upper Cook Inlet are characterized by q
relatively regular coastline with numerous sand and gravel beaches and
abutting -coastal lowlands, often drained by river systems !g.tjnating_ in
broad eituarine areas. Major storm tracks move northward off the Gulf of
A'laska into the south coastal highland areas, dropping precipitation on the
southern side and leaving the leeward (northern) side in somewhat of a rain
shadow. Headwater areas of the major dra'inages are subiect to greater
temperature fluctuations due to the influence of the continental climatic
zone.
1 Arctic Environmental Information and Data Center. N.d. Alaska regional
profiles: Southcentral Region. Prepared for the 0ffice of the Governor and
Joint Federal/State Land Use Planning Commission.
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Biota
Vegetation in the region is varied. The Sitka spruce-western hemlock forest
is restricted to the lower-elevation coastal areas from Prince l.lilliam Soundto lower Cook Inlet. Various associations of white spruce, b]ack spruce,
paper birch, balsam popular, black cottonwood, and quaking aspen trees are
cormon throughout the forested lowland areas away from the coast. Low and
ta1'l shrub corununities comprised primarily of willow, alder, and shrub birch
are common throughout the subalpine zone and in areas subiect to periodic
disturbance, such as floodplains and avalanche chutes. Dwarf shrubs and a
variety of herbaceous communities are common in alpine areas and lower-
elevation wetlands.
In addition to the rich marine life of Prince William Sound, lower Cook
In'let, and the Gulf of Alaska, the Copper, Sus'itna, Kenai, and Kasilof river
systems provide optimum conditions for the rearing of five species of
salmon, upon which most of the region's fishermen depend. Much of the North
Pacific's population of shorebirds and waterfowl use the Copper and Susitna
river deltas, as we1l as many smaller estuarine areas, for spring and fall
feeding and migratory staging areas. The region supports harvestable
populations of brown and black bears, moose, sheep, goats, caribou, Sitka
black-tailed deer, furbearers, waterfowl, and small game. Marine habitats
support healthy populations of sea otter, harbor seal, sea lion, be'lukha
whale, and many other species of whales.
Human Activities in the Region
As one would expect from the abundance of fish and wildlife in the South-
central Region, many human activitjes revolve around the commercial, sport,
subsistence, and persona'l uses of these resources. Commercial fishing,
seafood processing, and guiding of hunters and fishermen are important
segments of the regional economy. Maior fishing ports in the region include
Cordova, Valdez, Seward, Homer, and Kenai. Noncommercial harvest for
recreation and food is a goal of many residents of the reg'ion. The rapidly
growing tourist industry is often related to the opportunity to fish, hunt,
and view fish and wildlife.
Additional economic bases in the region are provided by Anchorage's role as
the state's center for banking, oil,9dS, and mineral companies, state and
federal government agencies, and service-related businesses. Agriculture
and cattle grazing are found primari'ly in the Matanuska-Susitna va'l1ey and
Kenny Lake area of the Copper River basin. Forestry is limited to small
private logging operations. 0il and gas development and production have
occurred in Cook Inlet and on the Kenai Peninsula for the last two decades.
There may a'lso be potential for oil and gas development in other areas of
Southcentra'l Al aska.
Infrastructure development is mjnimal by national standards, but the
Southcentral Region has the most extensive network of roads, rai'l lines, and
airstrips in the state.
14
Ivlarine Mammals
I.
II.
Harbor Seal Life History and Habitat Requirements
Soutlrrest and Southcentral Alasha
Map 1. Range of harbor seal (ADF&G 1973)
NAMEA. Conmon Name: Harbor sealB. Scientific Name: Phoc litul ina rj441C!,1_ (Shaughnessy and Fay
re77)
RANGEA. Worldwide
The North Pacific harbor seal is found in coastal waters from
northwestern Mexico along the North American coast as far north as
the Bering Sea, along the Aleutian Islands chain, in the Pribilof,
Commander, and Kuril islands, eastern Kamchatka, the Okhotsk Sea'
and northern Japan (Burns and Gol'tsev 1984). Burns and Gol'stev
('1984) could not substantiate the physical characteristics that
L7
seDarated P. v. Stejneqeri and P. v. richardsi (shaughessy and Fay
1gi7) and 3o reioined-Th-subspecies @.B. Statewide
Harbor sea'ls i nhabi t coasta'l waters f rom Southeast Al aska to the
Kuskokwim Bay-Nunivak Island region of Alaska and westard
throughout the A1eutians (ADF&G 1t76, Frost et al. 1982). They
are also frequently found in maior rivers where seasonal
concentrations of food species occur.C. Regional Distribution SummarY
To-supp'lement the djstribution information presented in the text,
a senies of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale'
bul some are at 1:1,000,000 sca'le. These maps are available for
rev'iew in ADF&G offices of the region or may be purchased from the
contract vendor respons'ible for their reproduction. In addition'
a set of colored 1:i,000,000-scale index maps of selected fish and
wild'life species has been prepared and may be found in the Atlas
that accompanies each regiona'l 9uide.1. Southwest. Harbor sea'ls occupy virtually a'll coastal areas
I n-Tn'ilouthwest Regi on . I1 I i amna Lake ap.pears to support a
year-round subpopulation (ADF&G L976). (For more detailed
narrative information, see volume 1 of the Alaska Habitat
Management Guide for the Southwest Region.)
Z, !out[cen[q!. Harbor seal s occupy v'irtual ly al I coastal
arle,efTi-[ne Southcentral Region and seasonally are found in
certain rivers and lakes (Pitcher and Ca'lkins 1979). (For
more detailed narrative information, see volume 2 of the
A'laska Habitat Management Guide for the Southcentral Region.)
III. PHYSICAL HABITAT REQUIREMENTSA. Aquatic
Harbor seals are typically found where water depths are'less than
30 fathoms (ADF&G 1976). They tolerate a wide range of tempera-
tures and water salinity (Bouiva and Mclaren 1979). Harbor seals
are generally considered a coastal species, but they have_been
seen up to iOO km offshore (Spalding 1964, Fiscus et al. 1976,
Wahl 1977).B. Terrestriall. Haulout qleql. Haulouts are used for re_s_tin9,9iving birth'
arr.d@oung.Theymaybeespecia.|1yimportantdurin9
the molt [pitctrer .|984). In the Gulf of A]aska, commonly
used haulout substrates include offshore reefs, rocks and
ledges, beaches of isolated islands, mainland or island
beaihes backed by c'liffs, sand and mud bars (often located in
estuaries), ice floes calved from tidewater glaciers, and sea
ice (Pitcher and Calkins 1979). 0n the northern coast of the
Alaska Peninsula, seals concentrate on shoals and sandbars
exposed during low tides, primari'ly in estuaries (Frost et
al . 1982). Ready access to water, isolation from
disturbance, protection from wave and wind action, and access
18
to food sources are characteristics often associated with
haulout sites (Pitcher 1981). -.In the Gulf of Alaska,
accord'i ng to Pj tcher and McAl I i ster ( 1981 ) ' a1 though
fidelity to a single haulout area was not consistent, there
was a itrong tendency to use one or, in some instances' two
hauling areas rePeatedlY.
IV. NUTRITIONAL REQUIREMENTSA. Food Species Used
in the'Gulf of Alaska, Pitcher and Calkins (1979) found that fish,
including wa'l1eye po'l1ock (Theragra cha.lcogralqna)' .capel.in
(Mat iotui vil lpgfs), herring (ciupee-iralensut)TalTlc cod (Gadus
ir;dfucepnaiuiJ, 'ir at ii iEil lffionecti dae) , euliffiniracroceptraTll ' it at ii iffi lffi:onecti dae) ,
mfi eliThys paci f i cus ) , and salmor (0ncorhvl
;Otr=mflAat i;eililns 'both octopus (OcloPus .5q.f and sqyid
(Gbnatibae)i and decapod crustaceans, maTnly ghrlmq, were--the
primary prly species consumed by harbor seals. In Prince William
bound,- the -most important food- i tems were po1_'lock, herping, and
cephaiopods, whereas along the Copper River delta the major prey
"a's eu'l achon (Pi tcher 19i7). Stomach sampl es col I ected i n the
A'f eutian Islands (Wilke 1.957, Kenyon 1965, Lowry et al . 1979)
included fishes, octopuses, and crustaceans.
B. Types of Feeding Areas Used
Hii^Uor seal s a-re opportunistic feeders and general 1y feed in
nearshore shallow waters (FAO 1976).
C. Factors Limiting Availability of Food
No pertinent discussion was found in the literature.
D. Feeding Behavior
Harbor-seals swallow small fish whole underwater. Larger fish are
taken to the surface, where they are eaten in pieces (Ronald et
al. 1982).
V. REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat1.' Puppinq. Puppinq appears to take p'lace at nearly. all
loHfrons whei^b sials'haul out (Pitcher and Calkins 1979).
Z. Breedinq. Actual mat'ing occurs in water. Some aggress'ive
5effidf related to bieeding occurs at haulouts (Bishop
1e67 ) .
Reproducti ve Seasonal i tY1.' puppinq. In Alaika, harbor seal s general'ly give birth
5-stilFn late May and mid Ju'ly, with most pups born during the
first three weeks of June (ADF&G 1973).
2. Breeding. Breeding usual'ly occurs from late June to late
ilfiIfrtr-ortly aftei femal.es have ceased nursi ng thei r pups
(Pitcher and Cal kins 1979).
Reproduct'i ve Behavior
Oui^ing the breeding season, males become aggressive toward other
males-and toward females. Actual breeding and probab'ly most of
the aggressive behavior occur in coastal waters (Bishop 1.967).
B.
c.
19
0bservation by Pitcher and Calkins (1979) indicated that the first
several houri fo1'lowing birth were critical to formation of the
mother-pup bond. It appeared that if disturbance separ.ated the
mother'and pup shortly after birth, before a str_ong bond was
formed, permanent separation often occurred, resulting in the
death of the pup.
Age at Sexual MaturitYg6th males and females become sexual'ly mature between three and
seven years of age (Bigg 1969, Pitcher 1977).
Frequency of Breeding
gredaing takes place-annually (Pitcher and Calkins 1979).
Fecundi ty
Generally one pup is born. Estimates of adult pregnancy rates
range from 92 to 100% (Pitcher 1981).
G. Gestation Period
From the time of breeding to the t'ime of pupping is about 330
days. However, because of a delaye.d implantati-on period of about
11 weeks (Pitcher and Calkins 1979), the actua'l gestation period
is about 255 daYs.H. Lactation Period
The reported lactation period ranges from three to six weeks
(Bishop 1967, Bigg 1969, knudtson 7974, Johnson 1976).
VI. FACTORS INFLUENCING POPULATIONSA. NaturalLittle is known about the effects of food availability, disease'
parasitism, and predation on harbor seal populations. However,
Stetter sea lions, killer whales, and sharks are known to prey on
both adult and newborn harbor seals (Calkins and Pitcher 1982'
Pitcher .|981). Pjtcher and Calkins ('1979) found that in the Gulf
of Alaska mortality rates for both sexes were high from bjrth to
four years. Estifiated mortality for females was 74.2% and for
mal es 79 .2%.B. Human-relatedA surmary of poss'ib1e impacts from human-related activities
includes the following:o Chronic debil itation due to ingestion or contact with
petroleum or Petro'l Products" ivlortality due to ingestion of petroleum or petrol productso Harassment, active and Pass'iveo Terrain alteration or destruction
" Entanglement in fishing nets or marine debris
(See the Impacts of Land and Water Use volume of this series for
idditiona'l information regarding impacts. )
VI I. LEGAL STATUS
Harbor seals are federally protected under the Marine Marmal Protection
Act (MMPA) of 1972. Native Alaskan residents may harvest harbor seals
withdut rirstriction under this act, providing harvest is not done in a
wasteful manner. The State of Alaska is considering petitioning the
D.
E.
F.
20
federal government for renewed managerial authority over 10 species of
marine mamrnals, including harbor seal.
VIII. SPECIAL CONSIDERATIONSA. Mo'lti nggbservitions by Pitcher and Calkins (.|979) in the Gulf of Alaska
indicated that the molt began about the first of June and extended
into early 0ctober. The highest proportion of molting animals was
found in late July.
During the molt, ieals are thinner than at any other._time (Pitcher
and Cilkins 1979). Stress occurs in molting seals (Ronald et al.
L970, Gercia and Smith 1976), and hauling. out during the molt may
be important to warming the skin (re-tt1 and fuy 1966).
Disturbance during the molt that causes hauled out seals to enter
the water could-be detrimental to their health (Pitcher and
Cal ki ns 1979) .
IX. LIMITATIONS OF INFORMATION
As was noted above (VI.A.), little is known about what factors ma.y'limit the availability of food for harbor seals nor the effects of
predati on on popu'lati ons .
REFERENCES
ADF&G. .|973. Alaska's wildljfe and habitat. Vol. l IR.A. Hinman and
R.E. LeResche, eds.]. Anchorage. 144 pp. + maps.
a pub'l i c proposal for
. I976. Al aska's wi I dl i fe management p1 ans, Southcentral Al aska:
the management of Alaska's wildlife. Juneau.
291 pp.
Bigg, M.A. 1969. The harbour seal in British Columbia. Fish. Res. Bd.
Can. Bull. 172. 33 PP.
Bishop, R.H. L967. Reproductio.n, dg€ d_etermination and behavior of the
hirbor seal (Phoca'vitulina) in the Gulf of Alaska. M.S. Thesis, Univ.
Alaska, College, 1ZfFp.
Boulva, J., and I.A. McLaren. I979. Biology of the harbour seal-, Phoca
vitulina, in eastern canada. Fish. Res. Bd. can. Bull. 200. 24 pp.
Burns, J.J., and V.N. Gol'tsev. 1984. Comparative biology of harbor seals,
Phoca vitutina Linnaeus, .|758, of the Commander, A'leutian, and Pribilof
T5Tandffis77.24inF.H.FayandG.A.Fedoseev,eds.Sov.iet-
American coo[erative rFearch on marine mammals. Vol.: Pinnipeds..|984. USDC: N0AA, NMFS.
Ca'f kins, D.G., and K.W. Pitcher. 1982. Population assessment, eco_logy, and
tr6phic relationships of Steller sea lions in the Gulf of Alaska.
Final rept. to OCSEAP. Boulder, C0. 129 pp.
2t
FAg (Food and Agriculture 0rganization of the United Nations, Advisory
Committee ori'Marine Resources Research). 1976. Mannals in the seas.
Ad Hoc Group III on seals and marine otters. Draft_-peR!. In
Symposium: scientific consultation on marine manrnals. FAO, Bergen'
Norway, 13 August-9 September 1976. ACMRR/MM/SC/4.
Fe1tzn E.T., and F.H. Fay. 1966. Thermal requirements IN VITRO of
epidermal ce1 I s from seal s. Cryobio'logy 3 :261-264.
Fiscus, C.H., H.tl|. Braham, R.|r|. Mercer, R.D. Everitt' B.D. Krogman'
P.D. McGuire, C.E. Peterson, R.M. Sonntag, and D.E. Withrow. L976.
Seasonal distribution and relative abundance of marine mammals in the
Gu'lf of Alaska. Pages 19-264 in Environmental assessment of the
Alaskan continental shelf. Vol. -T Principal investigators' reports
for October-December 1976.
Frost, K.J., L.F.Lowry, and J.J. Burns. 1982. Distribution of marine
mammals jn the coistal zone of the Bering Sea during summer and autumn.
ADF&G, Fai robanks . 188 PP.
Geraci, H.R., and T.G. Smith. 1,976. Direct and indirect effects of oil on
ringed teals (Phoca hispida) of the Beaufort Sea. J. Fish. Res. Bd.
Can. 33:1,976-1,984.
Johnson, B.W. 1976. Studies on the northernmost co1onies of Pacific harbor
seils, Phoca vitulina richardsi, in the eastern Bering Sea. ADF&G'
unpubl. rept. 67 PP.
Kenyon, K.l^l. 1965. Food habits of harbor seals at Amchitka Island'
Alaska. J. Manrm. 46:103-104.
Knudtson, P.M. 1974. Mother-pup behavior within a pupping c_ol_ony of harbor
seais (Phoca vitu'lina richardsi) in Humboldt Bay, California. M.S.
Thesis,'TETIsffimTvJumSol-t cn. 42 p.
Lowry, 1.F., K.J. Frost, and J.J. Burns. 1979. Potential resource-iompetiiion in the southeastern Bering Sea: fjsherie-s_ a1d phocid seals.
Pagbs 35-143 in Environmenta'l assesiment of the Alaskan continental
stret t. Vo] . F Ann. rept. NOAA, 0CSEAP.
pitcher, K.1l|. 1977. Population productiv'ity and food habits of harbor
sei'ls in the Prince t'lilliam Sound-Copper River delta area, Alaska.
Fina'l rept. to U.S. Marine Marma'l Conrmission No. MMC-75103. USDC.
National 'Technical Information Service. PB 226 935. 36 pp.
. 1981. The harbor seal (Phoca
-Ti[-pp.
vitul ina). ADF&G, Anchorage.
22
Pitcher, K.W., and D.G. Calkins. I979. Biology of the harbor seal' Ilgviiulina richardsi, in the Gulf of Alaska. 0CSEA.P final rept. USDC'
Eoffier' ffip.
pitcher, K.14., and D.C. McAllister. 1981. Movements and haulout behavior
of radio-tagged harbor seals, Phoca vitulina. Canadian Field - Nat. 95
(3):292-297 .
Ronald, K., E. Johnsofl, M. Foster, and D.Vanderpo'l . 1970. The harP seal '1977). I . Methods of hand'l i ng,
J. Zool . 48:1 '035-1,040.
Paqophilus qroenlandicus (Erxleben,
ffianA-diseases in captivity. Can.
Ronald, R., J. Se11y, and P. Hea1y. 1982. Seals Phocidae, Otariidae, and
0dobenidae. Piges 769-327 in J.A. Chapman and G.A. Feldhamer, eds.
Wild mannals of-North Americil Baltimore: Johns Hopkins Univ. Press.
Shaughnessy, P.D., and F.H. Fay. 1977. A review of the taxonomy an{ lgryen--clatu'r.i of North Pacific harbour seals. J. Zool., Lond. I82:385-417.
Spalding, D.J. 1964. Comparative feedilg fabits of the fur seal, sea lion' ani harbour seal on lne British Columbia coast. Fish. Res. Bd. Can.
Bull. 146. 52 pp.
Wah'|, T.R. 1977. Sight records of some marine mammals offshore from
Westport, Washington. The Murrelet 58:?L-23.
Wilke, F. 1957. Food of sea otters and harbor seals at Amchitka Island.
J. t{i1d1. Manage. 2I:24L-242.
23
Steller Sea Lion Life History and Habitat Requirements
Souttr'rest and Southcentral Alasha
Map 1. Range of sea lion (Gusey 1978; Kenyon and Rice 1961;
Cal ki ns , pers . conrn. )
I. NAMEA. Common Name: Sea lion, Steller sea 1ion, northern sea lion
B. Scientific Name: Elrletopias iubatus
I I. RANGEA. Wor'l dwi de
The range of Stel ler sea I ions extends from the southern
Cal ifornia Channel Is'lands northward along the eastern North
Pacific to Prince William Sound (P}lS), the Alaska Peninsul_a, the
A]eutian Islands, and the Bering Sea to the Bering Strait (Kenyon
and Rice 1961); westward through the Kurile Islands, the Conmander
Islands, and 0khotsk Sea of the Soviet Union; and south in the
25
western North Pacific to Hokkaido and northern Honshu in Japan
(Calkins and Pitcher 1982).B. Statewide
In Alaska, sea lions range in nearshore waters and seaward to the
continental shelf break from southeast Alaska north throughout the
Gulf of Alaska and west through the Aleutian Islands and Bering
Sea (Kenyon and Rice 1961).C. Regional Distribution SummarY
To supp'lement the distribution information presented in the text'
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale,
but some are at 1:1,0001000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition'
a set of colored 1:1.,000,000-scale index maps of se'lected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.
Sea I ion distribution is associated with spec'ific land areas
(rookeries, hau'louts, and stopover areas) where they concentrate
in conspicuous numbers for breeding, pupping, and resting (Calkins
and Pitcher 1982). (For more detailed narrative information, see
vol ume 2 of the Al aska Habi tat Management Guide for the
Southcentral Region. )
III. PHYSICAL HABITAT REQUIREMENTSA. Aquatic1. Water depth. Fiscus and Baines (1966) found that sea lions
EFagffi-rel ati vely shal I ow water ('less than 100 fathoms )
nearshore, although Kenyon and Rice (1961) have observed them
85 nautical miles offshore. These movements may be related
to shallow water depths found offshore.B. Terrestrial
Terrestrial habitat requirements for sea lions revolve around
rookeries, haulouts, and stopover areas (Ca1 kins and Pitcher
1982). Sea lions are rarely seen hauled out more then 200 m away
from water (Cal kins, pers. comm. ) .
A variety of areas are used seasonally as hauling out areas' but
all types provide areas free of water at lower tida'l stages.
These-areas'include 'lange rocks awash at high tide (Harbor Pt.)'
rocky beaches flanked by sand beaches (Sitkagi Bluff), beaches
with- large boulders (Cape St. Elias), and, rarely, sand bars
exposed lo storms and high tides (Middleton Island) (ibid.).-
During stormy weather and/or high-sea conditions, the majority of
sea lions remain in the water rather than on haulouts (Kenyon and
Rice 1961).1. Rookeries. Rookeries are terrestrial sites where adult ma'les
ac FiTe-[- defend terri tori es and where the ma j ori ty of
breeding and pupping activities take place (Cal kins and
Pitcher 1982). A rookery may be used as a hau'lout during
nonbreeding periods of the year.
26
2. Haulouts. Haulouts are any areas where sea lions haul out on
a Tegmr bas i s but where few or no pups are born ( i bi d. ) .
Sandegren (1970) described the haulout area on Lewis Island'
PWS, as being exposed to the sea, with a very irregular rock
substrate ranging from loose, round rocks a few decimeters in
diameter to bedrock. Cracks, overhanging ledges, and caves
are abundant.3. St_gry.g.L_C_reas_. Stopover areas are locations where sea lions
n-ave-6een-lghted on land but only on an irregular basis in'low numbers (ibid.). No specific descriptions of stopover
areas were found; however, habitat requirements are similar
to other areas used by sea lions (Calkins' pers. comm.).
IV. NUTRITIONAL REQUIREMENTSA. Food Species Used
Major prey items of sea lions are off-bottom schoo'ling species
(i.e.,'waileye po1lock, herring, cod, etc.), and it appears that
sea lions fled' where these species are abundant (Calkins and
Pi tcher 1 982).
Pitcher (1981) found that preferred food species of sea lions in
the Gulf of Alaska were walleye pol'lock (Theragra chalcogramma),
squids (Gonatidae), Pacific herring (Clupea ffingus palTlT) 'capelin'(Mallotus' vittosus), Pacifi-c cffiad@)'
saimon (O-rrcorhyrchns spp. ), octopus (Octopus spp.FTpins
(Cotti dae]ffishes ' (Pl euronecti daeJ- and rockf i shes(Cottidae)ffiffishes (Pleuronectidae and rockfishes
(Scorpaenidae). Wa'l1eye pollock was the predominant Pr€Y'
composing 58% of the total stomach volume and occurring in 67% of
stomachs-with food (Pitcher 1981, Calkins and Pitcher 1982).1. Southwest Region. The principal prey of sea lions along
ffi were wal]eye pollock and salmon (Calkins
the
and
Pitcher 1982).
The principa'l prey of sea lions from the Kodiak area were
cape'lin, walleye po11ock, salmon, Pacific cod, octopus,
skates (Raja spp.), and flatfishes (ibid.).
Examinatfrn-of seasonal use of prey in the Kodiak area indi-
cated that predation on salmon and capel in was largely
I imi ted to spri ng and summer. Thi s 1 i kely ref'l ected
seasonal, nearshore distribution associated with spawning by
these species (Hart L973, Jangaard 1974).2. Southcentral Region. In PWS, the principal prey of sea 'lions
@k, herring, squids, sculpins, and rock-
fishes (Calkins and Pitcher 1982).
Pacific herring and squids were used extensively by sea lionsin Pl,lS but were less important elsewhere in the Gulf of
A]aska (Pitcher 1981, Calkins and Pjtcher 1982).
Along the Kenai Peninsula coastline of the Gulf of Alaska,
the principal prey of sea lions were walleye po11ock, Pacific
tomcod, Pacific sandfish (Trichodon tridodon), octopus 'saffron cod (Eleginus graciluiliFPaciTiT cotl-(jbid. ).
27
B.
c.
Pitcher (1981) described additional food sources from the
Gulf of Alaska as including shrimps (Decapoda), Tanner crab
(Chionocoetes spp.), SPidei crab (HvaffiT, skate, Pacific
iand-fffi'-nd harbor seal (fho.g
3}iTJ-#a)rfuna in 16 of 34Stones up to 12 cm in d
stomachs from sea lions sampled in Alaska and California
(Fiscus and Baines 1966). Their purpose is not known.
Types of Feeding Areas Used
Sea lions typically feed nearshore or in relatively shallow water
(1ess than i00 fathoms) on the continental she'lf. They may travel
ionsiderable distances from haulout areas to feed (ibid. );
however, large groups (tOO or more) are seldom found more than 10
to 15 mi frot a-hauiinj ground or rookery (during breeding season)(ibid.). Smal'l groups (2-I2) and individuals occur farther from
land (ibid.).
Factors Limiting Availability of Food
Some food species are present nearshore only during certain
periods of the year (ibid.). Salmon and capelin, for examp_]e' are
lbundant near shore during spring and surnmer, and capelin ?re
abundant near Unimak Pass during summer (Fiscus and Baines 1966).
Sea lions appear to feed on most abundant prey species in the area
(Calkins and Pitcher 1982). The apparent recent increase of
pol'lock in the sea lion diet is concurrent with the jncrease in
iollock stocks in the Gulf of Alaska (Calkins and Pitcher 1982,
Pereyra and Ronholt 1976).
Feeding Behavior1. Daily cycle. From May through 0ctober near Unimak Pass, sea
Tions leff their haul ing grounds in early morning in large
compact groups, swam 5 to 15 mi to feeding areas, and
dispersed into groups of less than 50 animals of mixed sexes
and ages. In late afternoon, they reformed into larger
groups- and returned to haulout areas (Fiscus and Baines
1e66).2. Food size. The estimated mean fork length of walleye pollock
Effiifsea lions in the Gulf of A'laska is 29.8 cm (Calkins
and Pitcher 1982).
D.
3.Prey selection. Most of the important prey species of sea
Tfti's lnTlask-a are off-bottom schooling species (ibid). Use
of thi s prey type may be 'important i n mi nim'izi ng forag'ing
effort and conserving energy (Smith and Gaskin I974, Pitcher
V.
1e81 ) .
REPRODUCTIVE CHARACTERI STICSA. Reproductive Habitat
Breeding takes p'lace onB. Reproductive Seasonal ity1. Southwest Reqion.
land on the rookeries (Sandegren 1970).
Pitcher and Calkins (1981) observed that
aska births occurred between mid May and mid
between 5 and 26 June (Sugarloaf and MarmotJuly, with a peak
islands).
28
C.
Breeding on sugar'loaf and Marmot islands (gutt of Alaska)
occurs shortly after parturition, usually between late May
and mid Ju'ly, with a pbak between 7 June and 4 July (Pitcher
and Cal ki ns 1981 ) .2. Southcentral Region. Sandegren (1970), observing a small
ffion a haulout in PWS, found that most Pups
were boin from 29 l4ay through 1 July, with a peak from 10 to
12 June.
Breeding in PWS occurs from 10 to 14 days after females give
birth (Sandegren 1970).
Reproductive Behavior
Seb lions are polygynous, and most breeding.is done by bulls that
defend territ6riei- against other bul I s ( ibid. ). Males with
semi-aquatic territories (partially above and below the high-tide
line) were most involved jn breed'ing actjvjty. Some bulls
majntajn territories for over 60 days (ibjd. ). Cows initiate
breeding with distinct behavior directed towards territorial bulls
(ibid.).
Females leave their young for the first time 5 to l? days after
birth. Males do not attend or protect pups. Female departures
after the initial one are regular, with periods on land ranging
from 9 to 42 hours and periods at sea ranging from 9 to 40 hours
(ibid.).
The mother-offspring bond is usually one year' but adult females
have been observed nursing both a pup and a subadult (Calkins and
Pitcher 7982, Sandegren 1970).
Age at Sexual Maturity
Females mature between three and e'ight years; the average age at
first ovulation is 4.6 t 0.8 years, and at first pregnancy 4.9 t
1.2 years (Pitcher and Calkins .|981). One observation of a female
breeding at two years of age was reported. Males mature between 3
and 8 years, although the ages of most males (88%) defending
territories were between 9 and 13 years. It appears males become
sexual 1y mature before they are abl e to defend terri tories
(Calkins and Pitcher 1982).
Frequency of Breeding
Mature females breed-annually (Pitcher and Calkins .|981).
Fecundi ty
Females have a single pup (ibid.).
The pregnancy rate for females B to 20 years old in the Gu'lf of
Alaska was *f". The projected annual birth rate (after prenatal
mortality) for mature females in the Gulf of Alaska was 63%
(ibid. ) and 68% in Cal iforn'ia (Gentry 1970).
Sea lions delay blastocyst implantation until late September and
0ctober (Calkins and Pitcher 1982).
D.
E.
F.
VI. FACTORS INFLUENCING POPULATIONSA. Natural
Ri ce (1 968) conc'l uded that i n
eastern northern Pacific, killer offshore coastal waters of the
whales feed primarily on marine
29
mamma'ls, including Steller sea lions. Killer whales are
frequently seen in the Aleutian Islands near large Ste'ller sea'lion rookeries (ibid.), and predation likely occurs.
Pup mortality of 12.5 to 14% was observed by Sandegren (1970) in
Pl,lS. Injuries sustained from crushing and/or fighting adults were
main causes of death.
For female sea lions in the Gulf of Alaska, combined mortality
from birth to three years is estimated to be 53%; and for age
c'lasses 3 through 11, the average annual mortality is LL%.
Approximately 30% of the females born survive to reproductive
maturity. In males, morta'lity from birth to three years is 73%,
and the average annual mortality for ages three through five years
was I3%. Data are not avai'lable for accurately estimating
mortality in ma'les beyond age five. However, based mainly on the
age distribution of harem bulls, the mortality rate apparently
increases substantial'ly after age eight. By age 10, it is prob-
ab'ly about 25% and by age 14 about 50% (Ca'lkins 1984).
In the Gulf of Alaska, aborted fetuses are an important source of
prenatal mortality (Calkins and Pitcher .|982). Based on dec'lining
pregnancy rates , a monthly prenata'l mortal i ty rate .of 4.7% was
determined for sea lions in the Gulf of Alaska (Pitcher and
Calkins l981).
San Miguel Sea Lion Virus (SMSV) and leptospirosis are diseases
associaled with abortions in related pinniped species (Smith et
al. .|973, Smith et al. 1974, Smith et a'1. 1977). Seriological
evidence of both leptospirosis and SMSV has been detected in the
Gulf of Alaska sea lion population (Fay, pers. comm.). Further
studies need to be conducted to determine the extent of these
diseases and their effect on the sea lion population.
B. Human-rel atedA sunmary of possible impacts from human-related activities
includes the following:o Mortal i ty due to contact or i ngestion of petrol eum or
petroleum productso Passive and/or active harrassmento Decrease i n prey base due to oi'l /chemi cal pol 1 uti on or
competition with humanso Destruction of haulout and rookery siteso Entanglement in fishing gear or marine debris
" Harvest, change in level ('lega1 subsistence harvest, plus an
increase in i 1 legal harvest associated with increased
development activi ties )
(See the Impacts of Land and Water Use volume of this series for
additional information regarding impacts. )
VII. LEGAL STATUSA. Sea I ions are federa'l 1y protected under the Marine Mammal
Protection Act (MMPA) of 7972 (P.1.92-522). The 1egal subsistence
harvest of sea lions by Native Alaskan residents is provided for
by this act. The State of Alaska may petition the federa'l
30
government for renewed managerial authority over L0 marine mammals
in the state, including sea lions.
VIII. LIMITATIONS OF INFORMTION
SpeClfic movement and migration information is needed for Ste'ller sea
'lion popu'lations in the Gulf of Alaska.
lnforination on sea lion population dynamics is needed. Information on
factors limiting sea lioh iopulationi in the Gulf of Alaska is needed.
Such information includes data on predation and disease.
REFERENCES
calkins, D.G. .|984. Stel'ler sea lion. 11 J.J. Burns, ed. Marine mammals
species accounts. Wildlife Tech. BulT. 7. ADF&G, Juneau.
. .|984. Personal communication. Game Biologist, ADF&G, Div. Game,
-Tnctrorage.Calkins, D.G., and K.W. Pitcher. 1982. Populat'ion aSsessment, eco-1ogy' and
trophic relationships of Steller sea lions in the Gulf of Alaska.
0CSEAP. Final rept. RU-243. BLM. 129 pp.
Fay, F.H. .1984. Personal communication. l.ljldlife Biologist, Un'iv. Alaska,
Fai rbanks.
Fiscus, C.H., and G.A. Baines. 1966. Food and feeding behavior of Steller
ana Ca]ifornia sea lions. J. Mamm. 47(2):195-200.
Gentry, R.L. 1970. Social behavior of the Steller sea lion. Unpubl.
pn.n. Dissert. , Univ. Cal ifornia, Santa Cruz. 113 pp.
Hart, J.L. 1973. Pacific fishes of Canada. Fish. Res. Bd. Can. Bull. 180.
740 PP.
Jangaard, P.M. I974. The capel in (Mal lotus vil ]osus) .biology'- {i-str!!q---..'J-llon, exploitation and compositionlTTsh'-les. Bd. Can. Bull. 186.
70 pp. Cited in Calkins and Pitcher 1982.
Kenyon, K.W., and D.t^l. Rice. 1961. Abundance and distrjbution of the- Steller sea lion. J. Mamm. 4?:223'234.
pereyra, W.R., and L.L. Ronholt. I976. Baseline studies of dimersal re--sources bt the northern Gulf of Alaska shelf and s1ope. USDC: N0AA'
Processed rept., NMFS' NWAFC. 281 pp.
Pitcher, K.W., 1981. Prey of the Steller sea lion, Eumetopias iubatus, in
the Gulf of Alaska. Fish. Bull. 79(3):467-472.
pitcher, K.W., and D.G. Calkins. 1981. Reproductive biology of the Steller
sei tioni in the Gulf of Alaska. J. Mamm. 62(3):599-605.
31
Rice, D.W. 196B. Stomach contents and feeding behavior of killer whales in
the eastern north Pacific. Norsk Hvalfangst-Tidende 57(2):35-38.
Sandegren, F.E. 1970. Breeding and maternallion (Eumetopias iubatus) in Alaska.
Col lege. 138 pp.
Smith, G.J.D., and D.E. Gaskin. 1974. The diet of harbor porpoises
(Phocena phocena) in c_oastal waters of eastern Canada with special
rEffin-ce;To TF-e Bay of Fundy. Can. J. Zool . 52:777-782.
Smith, A.W., T.G. Akers, S.H. Madin, and N.A. Vedros. .|973. San Miguel Sea
Lion Virus isolation, pre'l'iminary characterization and relationship to
vesicular exanthema of'swine virus. Nature 244 (5411):108-110.
Smith, A.tl|., R.J. Brown, D.E. Ski11ing, and R.L. De]ong. 1974. Leptospira
pomona and reproductive fajlure in California sea lions. J. Am. Vet.
iled. Assoc. 165:996-998.
behavior of the Steller sea
M.S. Thesis., Univ. Alaska,
Smith, A.l'l., R.J. Brown, D.E. Ski11ing, and
occurring leptospirosis in northern fur
J. l.Jildlife Diseases, 13.
Natural 1y
urs i nus )
H.L. Bray. 1977.
seals (Callorhinus
32
I.
II.
Sea Otter Life History and Habitat Requirements
Southrest and Southcentral Alasha
Map 1. Range of sea otter (Kenyon 1969, Lensink 1962)
NAMEA. Common Name: Sea otterB. Scientific Name: Enhydra lutris
RANGEA. Wor'l dwi de
Sea otters historically inhabited the coastal areas of the North
Pacific Ocean and the Bering Sea from the Kamchatka Peninsula
south to the Kurile Islands and Hokkaido Island (Japan), eastward
through the Cormander, Pribilof, and Aleutian i!'landsr fnd qloqg
the North American coast from the Alaska Peninsula, Kodiak Is'land'
and Prince l'lilliam Sound (PWS) to southern California (Kenyon
1969, Lensink 1962).
33
B.
Corrnercia1 harvesting eliminated sea otters from most of this
range. In I 911, conrnerci al harvesti ng of sea otters was
curtailed, l eaving on'ly remnant popu'lations present in widely
scattered areas oi the sea otter's former range (Lensink 1960).
Sea otters have now repopulated most of their former ranges.
These populations have resulted from range expansion (Schneider,
pers. corm.) or transplants taken from high density areas (Burris
and McKnight 1973).
Statewi de
Sea otters occur in nearshore A]askan waters from Southeast Alaska
(with smal'l popu'lations near Chichagof , Yakobi, Maurelle, Barrier,
ind Coronation is'lands resulting fiom transplants in the 1960's)
to Yakutat (where smal'l groups have become established), through
PllS, the Kenai Peninsula extending into Kachemak Bay, the Kodiak
archipelago, a'long the south side of the A'laska Peninsula'
throughout the Aleutian Is'lands, and along the north side of the
Alaski Peninsu'la as far as Port Heiden (Kenyon 1969, Burris and
McKnight '1973). Sea otters have occasionally been reported from
the Piibilof Islands and northward; however, permanent populations
are not 1ikely to occur in areas of winter sea ice (Kenyon 1959'
Schneider and Faro 1975).
Regional Distribution Surunary
To supplement the distribution information presented in the text'
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale'
but some are at 1:1,0001000 scale. These maps are availab'le for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition'
a set of colored 1:1,000,000-scale index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.
1. Southwest. Sea otters are present in substantial numbers all
E-lo-ng-Th.e Aleutian Islands where favorable habitat is found.
Important concentrati on areas i nc'l ude the Rat and De1 arof
islands, Andreanof Islands, and the area north of Unimak
Island. (For more detailed narrative information' see volume
1 of the Alaska Habitat Management Guide for the Southwest
Regi on . )2. Southcentral. Sea otters are locally abundant throughout
FfiSl-liEEFthere'is sufficient suitab'le habitat to suppport
them. Small groups and single individuals are cormon, and
larger established groups are found in many areas of the
sound. Sea otter populat'ions are expanding in Pt.lS, and
adjacent historic areas with suitable habitat will be sett'led
by exploring members from this core population. Densities of
15 to 30 otters per square mile of habitat, l0 fathoms or
less, can be expected (Johnson, pers. comm.).
Some areas where sea otters are abundant in Pl'lS include
College and Harriman fiords, Hinchinbrook Island, Montague
c.
34
Island, sheep Bay, 0rca Inlet, Green island, Port.Fidalgo'
and Poit grav'ina -(i'i tcher L975:' Johnson ' pers . comm. ) .
0n the Kenai Peninsula, sea otters are present and abundant
almost everywhere a1 ong the southern coast, i ncl udi ng
Elizabeth Island, Perl island, Nuka Bay, Chugach Bay, and
Harris Bay. (For more detailed narrative information, see
volume 2-of the Alaska Habjtat Management Guide for the
Southcentral Region. )
III. PHYSICAL HABITAT REQUIREMENTS
The two most'important sea otter habitat requirements are an abundant'
high qual ity food supply, and clean, uncontaminated water. These
hab'itat requirements are the same throughout the year.
A. Aquatic1. Water quality. C1ean, uncontaminated water is essential for
sfilffiffiFvival . Sea otters rely on a dense coat of fur
to trap a layer of a'ir and prevent water from penetrating.!o
the skin. Cbntaminat'ion of the fur will interfere with this
insulating air 1ayer, greatly increasing thermal conductiv-
i ty, and- the ahimal w j I I qui ckly d'ie of hypothermi a
(Sihneider 1976, Kooyman et al . 1976) To prevent fur contam-
ination, a considerable proportion of the sea otter's dai'ly
activity pattern (up to' 6O% during some time periods) is
spent grooming their fur (Siniff et al. .|982).
Sba otiers sribjected to contamination of 130-260 cmz (less
than 10%) of their pelage by only 25cc of Prudhoe Bay crude
oil showed significant changes in both level of activity and
activity pattern ('ibid. ). These changes were manifested
main'ly in increased grooming activity.
Metabolic rate increases up to 40% above average have been
observed for sea otters wtth 20% of their pelage contaminated
(Costa and Kooyman 1979). An otter that was complete'ly
contaminated by oil djed less than 24 hours after soi'lage.
Results from an autopsy suggested hypothermia as the cause of
death, although toxicity fiom oi1 ingestion was also possible
(Siniff et al. .|982).
2. Sea ice. Sea otters appear to be limited in their northward
eEns-ion by permanenl sea ice conditions (Kenyon 1969).
Temperatures that allow the rapid formation and advancement
of'sea jce are detrimental to otter populations. Schneider
and Faro (1975) observed ice-related morta'lity near Port
Moller during the below normal winters of L97L and I972
(average 5.6--10.3'C below normal temperature). Ice-related
mortality of sea otters was also observed in this area in.|974 and l9B2 (Frost et al. ]982).
3. Water depth. Sea otters inhabit a wide range of water
deptFb-.--Tccessi bl e habi tat i s cons i dered to Qe anywhere
witnin the 75-m depth curve (Calkins and Schneider 1984).
There are observations of sea otters diving to depths of 90
m' and adults are often seen feeding in depths up to 80 m;
35
IV.
however, al'l known self-sustaining popu'lations have accessto, and heavily use, waters'less than 40 m deep (iUia.1.
4. Substrate. Sea otters favor shallow water areas with a\r f bottom substrates, ranging from rocks and under-
water reefs to soft sediment bottoms and sandy beaches
(Schneider, pers. conm.). Coastlines adjacent to extensive
areas of sha'l'low underwater reefs are particularly attractive
(Kenyon 1969). The sea otter's association with kelp beds
has been assumed to be a necessary habitat requirement.
However, large permanent otter populations occur in areas
where no kelp beds exist (e.g., southeast Bristol Bay)
(Calkins and Schneider 1984).B. Terrestri a] Cover Requi rements
Severe winter storms, with associated rough-water conditions, can
prevent otters from foraging efficient'ly, resu'lting in serious
food-related stress (Kenyon 1969). Lee shorelines of prominent
points or capes and offshore is'lets can provide protected areas
(Lensink t962). Haulout areas, consisting of intertidal rocks or
areas above the storm-tjde I i ne, are used by some otter
populations but are not considered essential (Schneider 1978).1. Southwest. Kenyon (1969) reported that otters regular'ly haulffi-Tn Tfre Aleutian and Shumagin islands. In those areas'
they favor rocky points but also utilize sand beaches.2. Southcentral. Sea otters in Ptlls have been observed hauled
oriT on lce f 'loes, i ntertidal rocks, and on shore above the
high-tide line during winter. Sea otters also regular'ly haul
out on sand bars exposed by low tide in areas such as Orca
Inlet (Johnson, pers. comm.).
NUTRITIONAL REQUIREMENTS
Abundant food at accessi b]e depths i s cl ear"1y the most important
habitat requirement (Calkins and Schneider 1984). If this food sourceis not available, otter densities wi'll remain low or populations will
di sperse.
Sea otters require large quantities of food, about 20 to 25% of their
body weight per day (average 5 kg), to support their high metabolicrate ( Kenyon 1969 ) . Thi s requi rement makes i t necessary that an
abundance of high quality food be available to the otter population atall seasons of the year (ibid.). In areas where sea otter popu'lations
are at or near maximum density, further population growth appears to be
limited by the availability of high-quality food items (Schneider,
pers. conm. ).
Food Species Used
Sea otters are opportunistic feeders, and their diet depends
largely on what is available (ibid.). They generally feed on a
wide variety of benthic invertebrates (Calkins and Schneider
1984)i however, when these organisms are scarce, otters are known
to prey on other species (e.g., slow-moving fishes) (Kenyon 1969).1. Southwest:
A.
36
a. Aleutian Islands. In the Aleutian Islands, otters are
ffiy species of invertebrates and mol1usks
and some speci es of f i shes ( i bi d. ) . The fo1 'lowi ng are
some of the species eaten by sea otters: green sea
urchin (Stronqylocentrotus drobachiensis), mussel(Musculus'ffi]]a-ildJe sea stars(I€pmrias spl, HenFiEit Tpi Tanner crab
minnocoffi bairdi), Img crab (Paralithodes
pfatypus ) , octopuilQltopqr spp. ) , chi tons (WptoEF-i ton;te1]fii . t impets'T-i,"^-ncm-aea
"
spp. ), sna j I s TBffiumTpf,, iea cucumbers @!g spp. ), pearly rnon]a
b.
(irbdodesmus macroschisma-), lTSSEfish (Cycloptericthys
qT;5e rf red TFTsn-To rd-- ( Hem i'l ep i dotu s FiLT@t]|l.-----and rock greenl i ng (Hexagranrrnos supGici I 'iosus ) .
Northern -side of n]ffini-nsula. -No specific sea
m the north side of
the Alaska Peninsula (Schneider, pers. comm.). It is
believed, however, that otters in that area feed heavily
on c'lams, crabs, and other invertebrates (Calkins and
Schneider 1983).
Large populations of bivalve mollusks, including surf
2.
clams
.(Spisula pqlynyma), Alaskan tellin (Tellina
I utea ) , -nd-cockTes ( Serri pes groenl andi cus , S.
l_aper6usi i ), and marine sna-iTi-(Ni-t'leptu@p.J-have beendlffid' ln portions of BristoTTay (Hughes et al .
1977, Maclntosh and Somerton 1981). Distribution of the
clam species was greatest between 10 and 22 fathoms
(Hughes et al, 1977), well within the sea otter diving
range. Snail distribution was more widespread but still
accessible to sea otters. These species represent good
food sources for sea otters (Schneider, pers. comm.).
Southcentral. In the Montague Straits area of PWS, Calkins
w|foundthatseaottersfedprimari.|yonbenthic
invertebrates, inc'luding clams, crabs, octopuses, sea stars,
mussels, and sea cucumbers. No fish species were observed to
be consumed.
Major prey species are similar throughout Pl,lS, with primary
importance placed on the prey item most available. Fish have
bebn observed to be taken as prey but only rarely (Johnson,
pers. comm. ) .a. Primary. Calk'ins (1972, .|978) determined that five
speciei of clams were the most often consumed prey itemin hjs study area in Pl,lS. The most common'ly consumed
species was Saxidomas gigantea; however, the species
taken depends upon wnat lTTocaTly abundant. Other clam
species included Protothaca staminea, !E truncata,
Macoma i nqu i nata , anTl{lTrrcongrua ;--Tddi TTonaT-Tavored
ToofsFETes Tncludeif c@ cheiragonus
Cancer spp. ), octopuses (0ctop anffiuGTs
II[EiTr: edul is) (Cal kins le72;Te78).
37
B.
b. Secondary. 0ther prey species consumed, but not
Freffi, i ncluded sea stars (Evasterias troschel i i)
hnd sea cucumbers (Cucumaria sp.)lT5'ililT.
Types of Feeding Areas Used
Sea otters prefer to feed in shallow water, usually less than 55m. The maximum depth of food dives may be up to 90 m (Kenyon
1969). Subadult females and females with pups usually occur in
areas of higher prey density and in shallower, more protected
waters than do ma]es ( Schnei der 1981) .
Sea otters forage from the intertidal zone to generally within 3to 10 mi of shore, apparently following shal'low-water areas to
forage. The farthest offshore observations range from 17 mi
(Kenyon 1969) to over 30 mi (Schneider, pers. conrm.). 0ffshore
foraging movements appear to be associated with weather
conditions. After severe storms, otter concentrations tend to be
nearshore, whereas after a calm period animals are distributed
farther offshore (Schneider 1981).
Factors Limi ti ng Avai'labi I i ty of Food
Norma'l foraging activity in a high-density otter population can
deplete the food supp'ly, thus affecting the otter population. Sea
otters will exploit a favored prey species, utilizing it unti'l the
availability or size is great'ly reduced. This concentration on a
sing'le food species appears to have happened with sea urchins at
Amchitka Island (Lensink 1962, Kenyon 1969, Estes and Palmisano
1974), clams in PWS (Calkins and Schneider 1983), and red aba'lone
(Haliotis spp.) in California (Lowry and Pearse 1973)
Sea- oTters exert a significant influence on marine nearshore
communities and have been described as a keystone species (Estes
and Pa]mi sano 1974).
Winds of 20 to 30 knots and accompanying rough seas force most sea
otters to find protection in sheltered areas or near shore. Long
periods of rough sea conditions can prevent otters from foraging
in some areas (Lensink 1962).
Feeding Behavior
Sea otter feeding behavior is directly associated with the high
energy requirements of the species and the avai'lability of high-
quality food items. The level of feeding activity needed to meet
those requi rements vari es wi th the qua'l 'ity and quanti ty of prey
items. If h'igh-qua'lity food items are present in suff icient
quantity, otters need to spend only a smal I amount of time
foraging. t,Jith a poorer food source, a proportionately larger
amount of foraging time is necessary (Schneider, pers. corm.).
In general, feeding behavior accords with the following pattern:
Soon after day'light, otters move from resting areas to adiacent
feeding areas (usua'lly less than 100 yd) and forage until
approximately 1000 hr. Grooming and resting occur throughout the
day, with a peak near 1200 hr. Foraging continues during the day'
wi th movement from foragi ng areas occurri ng by sundown andactivity usual'ly ceasing by dark (Lensink L962). However,
patterns of activity are variab'le, and night feeding is not
c.
D.
38
uncommon in areas
comm. ) .
At Amchitka Island, anof the dayl ight hours
of poorer qua'lity food sources (Johnson' pers.
area of low prey availability, about 5I-55%
are spent forag'ing (Estes 1974, Kenyon
V.
re6e).
In contrast, otters had to spend only t7% of the daylight hours
foraging in an area of high prey availability (Estes et al. 198?).fhe aitierence in foraging activity is related to prey availabil-
ity and quality (ibid.).
Sel otters use a rock or shell held on their chest to break open
some food items (Kenyon 1969, hlild and Ames 1974, Estes L974).
No apparent differences in feeding, resting' or grooming behavior
occur between summer and winter (Estes I974).
REPRODUCTIVE CHARACTERISTI CS
The sea otter reproductive strategy is characterized by a 1ow nata'lity
rate and a relatively long rearing period by the female, which.results
in a high rate of suivival for theyoung (Schneider, pers. comm). This
strategy, however, does not allow for a rapid increase in population
size.
Lensink (1962) described discrete male and female areas around Amchitka
Island (Southwest Region). He speculated that females used areas of
more favorable habitat, and that scattered territorial males excluded
younger males from these female areas. Younger or nonterritoria'l males'r'emain in peripheral male areas (Lensink 1962). 0ther authors (Kenyon
1969, Schne'ider 1978) have found thjs segregation to occur in other
A1euti an I sl ands popul ati ons .
Calkins (1972) did not observe discrete sexual segregation in PWS;
however, breeding territorial ity was observed between two males.
Garshelis (1983) -and Johnson (pers. comm.) observed male and fema'le
areas in an expanding population in Pt,lS. Because of the transitjonal
nature of an expanding population, these areas do not exhibit the
classical sexual' segregatibn observed in the Aleutians (Schneider,
pers. comm.).A. Reproductive Habitat
Calm waters within female areas
used for breeding (Kenyon 1969).B. Reproductive Seasona'lity
near feeding and resting areas are
Breeding behavior has been observed in all
occurring in September-0ctober (Kenyon
seasons, with a peak
1969, Lensj nk 1962,
Schneider 1978).C. Reproductive Behavior
Maies maintain exclusive areas of space (territories) within
female areas during the breeding peak (Kenyon 1969). Surp'lus
males wait on the periphery of female areas for estrus females to
approach (Schneider, pers. comm.).
Pairs remain together for three or more days (Kenyon 1969).
39
D. Age at Sexual Maturity
Ma'les reach sexual maturity at about five to six years (Schneider
1978). Females are sexually mature at about three to four years
E.
(Schneider 1978, Kenyon 1969).
Frequency of Breeding
The breeding interval is approximately two years (Schneider L972,
Kenyon 1969, Calkins 1972). However, females are physiologically
capable of annual breeding. Annual breeding appears to be
related to the food supply (Calkins and Schneider 1984). In areasof abundant food supplies, young animals are capable of providingfor themselves at an earlier d9€, eliminating the need for the
adult female to supply food and releasing her back into the
breeding portion of the population (Schneider, pers. conrm).
Fecund'i ty
Single births are usual; however, twinning does occur in about 2%of al I pregnanci es exami ned ( Cal ki ns and Schnei der I 984) .
Survival of more than one pup has never been observed. The femaleis unable to provide sufficjent food and care for more than one
pup (Schneider 1978, Lensink 1962, Kenyon 1969).
The gestation period averages 7.5 months, according to Schneider
(1972), and 8 to 9 months according to Kenyon (1969). The fetus
is implanted about one-half of this time (Schneider, pers. conm.).
Pupping occurs throughout the year, peaking in April, May, and
ear'ly June (Schneider 1981, Kenyon 1969).
F.
VI. FACTORS INFLUENCING POPULATIONSA. Natural
High-density otter populations close to carrying capacity may
experience competition for food, with a resulting higher mortality
rate for juvenile and older animals (Kenyon .|969, Lensink 1962).
Survival of pups is usually excellent until weaning, but mortalityof recently weaned otters can be high in areas of limited food
avai'labil ity. This juveni'le mortal ity appears to be a major
popu'lation-regulating mechanism in populations at or near carrying
capacity (Ca'lkins and Schneider .|984).
Severe weather condi ti ons wi th h'igh w'inds and rough seas can
prevent otters from obtaining adequate food supplies. Mortality
among otters can be very high, primari'ly from injuries in rough
seas, disease, and starvation leading to enteritis (Kenyon .|969).
Bald Eagles at Amchitka Island have been observed preying on young
otters and may be a significant cause of mortality when pups are
small (Shemod et al . 1975, Kenyon 1969).
Predation by white sharks occurs in California and may be a
significant mortality factor but has not been documented in Alaska
(Kenyon 1969).
Predati on by ki 'l I er whal es i s poss i b'le; however, i t has not been
documented in Alaska and is not considered significant (ibid.).
The periodic formation of heavy sea ice appears to be the limitingfactor in the northeastern range expansion of sea otters in
Bristol Bay (Schneider and Faro 1975).
40
B. Human-relatedo Entanglement in fishing nets or marine debriso Passiie harrassment (tour boats, increased pleasure boating)o Mortality due to contact with or ingestion of petroleum or
petro'leum Productso becrease in prey base due to oil/chemical pollutiono I1 legal shooting
(See the impacts of tand and Water Use volume of this series for
additional information regarding impacts. )
VII. LEGAL STATUS
Sea otters are federal'ly protected under the Marine Mammal Protectjon
Act (MMPA) of I972, (P[.92-522). The lega1 harvest of sea otters by
Native reiidents is provjded for by this act. The State of Alaska may
petition the federal government for renewed managerial authority over
10 marine mammals, including the sea otter.
VI I I. SPECIAL CONSIDERATIONS
Curyent and proposed petroleum deve'lopments and related activity in Pl,lS
will inevitably result in the contamination of the marine ecosystem.
The sea otter is a high'ly visible and dynamic part of that ecosystem.
The otter and its pr-ey would be direct'ly affected by contaminated
waters resulting from petroleum pollution.
IX. LIMITATIONS OF INFORMATION
Because of the dynamic status of sea otter populations in SC Alaska,
d'istribution and abundance surveys need to be conducted for the east
side of the Kenai Peninsula, eastern PWS near Cordova, and continued in
other areas of PWS.
Evidence indicates that classjcal male areas, as found in the Aleutian
Islands, do not presently exist in PWS. Further studies are needed to
determine at what level expanding sea otter populations become sexually
segregated into permanent areas.
Stuales are needed to determine the effect of sea otter foraging on
conmercia'l 1y important crab stocks. The breeding interval ( i.e. 'annual or biennial ) and potentia'l rate of increase for expanding
populations in Pl'lS needs to be determined.
REFERENCES
Burris, 0.E., and D.E. McKnight. .|973. Game transplants in Alaska. ADF&G
Tech. Bul 'l . No. 4. Juneau ' Ak.
Calkins, D.G. L972. Some aspects of the behavior and eco'logy of the sea
otter, Enhydra lutris, in Montague Strait, Prince William Sound,
Al as ka . TSTheTTs , Un i v . Al as ka . 55 pp.
. 1978. Feeding behavion and major prey species of the sea otter,
-Entr"ydra
lutris, in Montague Strait, Prince William Sound, A'laska.
TTTfi-ulT. -7it( 1) : 125- 131 .
41
Calkins, D.G., and K.B. Schneider. 1984. Sea otter.
Wi 'ldl i fe Tech. Bul I . No. 7 . ADF&G, Juneau .
Kooyman. 1979. Effects of crude
abi I i ty to thermoregul ate. Thi rd
of marine mammals, Seattle, Wash.
In J. Burns, €d.
oil contamination on the
biennial conference on
Costa, D., and G.
sea otter's
the biology
Estes, J.A. 1974. Population numbers, feeding behavior, and the eco'l99ical
importance of sea otters in the Western Aleutian Islands, Alaska.
Ph.D. Dissert., Univ. Arizona. 125 pp.
Estes, J.A., and J. Palmisano. 1974. Sea otters: their role in structuring
nearshore cornmunities. Science 185:1,085-1,060.
Estes, J.A., R.J. Jameson, E.B. Rhode. 1982. Activity and prey selection
in the sea otter: influence of population status on comnunity
structure. Am. Nat. 120( 2) :242-258.
Frost, K.J., L.F. Lowry, and J.J. Burns. 1982. Distribution of marine
marnmals in the coastal zone of the Bering Sea during surnmer and autumn.
OCSEAP final rept. RU-613. Jan. 1981-Aug. 1982. 188 pp.
Garshe'lis, D.L. 1983. Ecology of sea otters in Prince William Sound,
Alaska. Upub1. Ph.D. Thesis, Univ. Minn. 32L pp.
Hughes, S.E., R.t.l. Nelson, and R. Ne'lson. 1977. Initial assessments of the- distribution, abundance, and quality of subtidal clams in the SE Bering
Sea. NWAFC processed rept. USDC: NOAA, Seattle, WA. 35 pp.
Johnson, A. .|984. Personal communication. t,lildlife Biologist' USFl{S,
Anchorage, Ak.
Kenyon, K.l,l. 1969. The sea otter in the eastern Pacific Ocean. USFWS'
N. Am. Fauna 68.
Kooyman, G.1., R.L. Gentry, and W.B. McAlister. 1976. Physiological impact
of oi'l on pi nni peds . USDC , unPubl .
Lensink, C.J. 1960. Status and d'istribution of sea otters in Alaska.
J . Mamma'l . 41( 2) :172-182.
. 1962. The history and status of sea otters in A'laska. Ph.D.
TlTsert., Purdue Univ. 188 pP.
Lowry,1.F., and J.S. Pearse. 1973. Abalones and sea urchins in an area
inhabited by sea otters. Mar. Biol. 23:213'219.
Maclntosh, R.A., and D.A. Somerton. 1981. Large marine gastropods of the
eastern Bering Sea. Pages 1,215-1,228 in D.W. Hood and J.A. Calder,
42
eds. The eastern Bering Sea shelf: oceanography and resources. Vol. 2.
USDC: 0MPA, N0AA.
Pitcher, K.W. 1975. Distribution and abundance of sea otters, Steller sea
lions, and harbor seals in Prince l'lilliam Sound, Alaska. ADF&G,
unpubl. Rept. 37. 22 pp.
Schneider, K.B. I972. Sea otter report. ADF&G, Fed. Aid l.lildl. Rest.
Proj. W-I7-4.
. 7976. Distribution and abundance of sea otters in southwestern
-gristolBay.Pages469-526inEnvironmentalassesSmentoftheAlaskan
continental shelf. Vol. 1. -N0AA/OCSEAP (fina1 rept.), quart. rept.,
0ct. - Dec.
. 1978. Sex and age segregation in sea otters. Fed. Aid in t^lildl.--ret. w-17-4-8. 45 pp.
. 1981. Distribution and abundance of sea otters in the eastern--Bering Sea. Pages 837-846 in D.l.l. Hood and J.A. Calder, eds. The
eastein Bering Sea shelf: ocEl-nography and resources. Vol. 2. USDC:
oMPA, NoAA.
. 1983. Personal communications. Regiona'l Research Coordination,--A'DF&G, Di v . Game, Anchorage.
Schneider, K.8., and J.B. Faro. 1975.
J. Mamm. 56(1):91-101.
Sherrod, S.K., J.A. Estes, and C.M. White. 1975. Depredation of sea otters
by Bald Eagles at Amchitka Island, Alaska. J. Mamm. 56(3):701-703.
Siniff, D.B., T.D. Williams, A.M. Johnson, and D.L. Garshelis. 1982.
Experiements on the response of sea otters Enhydra lutrjs to o'il
contamination. Biol. Cons. 23:26L-272.
l{ild, P.W., and J.A. Ames. I974. A report on the sea otter Enhydra'lutris L. in California. Calif. Dept. of Fish and Game, Mar. Res.
JEhlnept. 20:1-93.
Effects of sea ice on sea otters.
43
Terrestrial lfdammals
Sitha Blach-tailed Deer
Iife History and Habitat Requirements
Soutlrwest, Southcentral and Southeast Alasha
\
a
a
I.NAME
A.
B.
" 42Qt
Map 1. Range of Sitka black-tailed deer (ADF&G 1973)
Conunon Name: Si tka b'lack-tai I ed deer
Scientific Name: 0docoileus hemionus sitkensis
II. RANGEA. Worldwide
Sitka black-tailed deer are found in the heavily timbered regions
of the north coast of British Columbia and Southeast Alaska.
Several transplants have increased deer range throughout the
northeast Gulf of AlaskaB. Statewide
Deer are indigenous to the dense coastal forests of the south-
eastern Alaska-n mainland and most islands as far north as Glacier
Bay. Several successful transplants have extended deer range to
47
include most of the Kodiak archipelagon Prince Hilliam Sound
(Pt,{S), and the Yakutat area.C. Regiona'l Distribution Summary
To supplement the distribution information presented in the text,
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale,
but some are at 1:1,000,000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition,
a set of colored 1:1.,000,000-sca'le index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.1. Southwest. Deer have been reported throughout the Kodiak
art-hTF6Tl-go, wi th I ow dens i ty deer popul ati ons becomi ng
established in the previously unoccupied southwest portion of
Kodiak Island. (For more detai'led narrative information, see
volume 1 of the Alaska Habitat Management Guide for the
Southwest Region. )2, Southcentral. Deer have been reported th_roughout the Pl,lS
arEEllTffiFing primarily on the larger islands. Some deer
populations, however, occupy small mainland areas adiacent to
PWS. (For more detailed narrative information, see volume 2
of the Alaska Habitat Management Guide for the Southcentral
Regi on. )3. Southeast Region. Deer occur natural 1y throughout thecffi of southeastern Alaska (Alexander
Archipelago) and in a narrow strip along the adjacent
mainland. The precipitous Coast Mountains, with extensiveice fields, constitute an eastern barrier to deer. The
continental , subarctic cl imate terminates the natura'l
northern distribution of deer above Juneau (lllallmo 1981).
Deer were transp'lanted to Yakutat and to several areas around
Lynn Cana'l (Burris and McKnight 1973). A persistent
population was established in Yakutat and on Su'llivan Island.
Deer occur i n very I imi ted numbers a1 ong the Chi I kat
Peninsula and along the Chi'lkat River.
III. PHYSICAL HABITAT REQUIREMENTSA. Aquatic1. Water quantity. Dietary water js obtained from snow in
winEeFl@laden succulent vegetation in rainy periods, and
occasionally from water bodies in dry periods (Cowan 1956).B. Terrestrial Cover Requirements1. Conditions providing security from predators or other distur-
bances:a. Southwest Region. Smith (1979) described how deer often
@swimming.b. Soutlegst Begion. Clear-cutting adjacent to mai_or roadsffioads without a buffer zone results in a
48
reduction of the use of cuts by deer because of the
continual disturbance (Taber and Raedeke 1980).
Conditions providing protection from natural elements;
a. Southwest Region. Cottonwood, birch, scattered spruce
@e alder thickets a'lo_ng :t99p.d.raws are
irsed for cover by deer on Kodiak Island (Smith 1979).
Low-elevation coastal Sitka spruce stands are used to
some extent throughout the year. Deer use the coastal
fringe Sitka spruce forests in varying amounts every
wintdr, although these areas become very critical in
winteri of deep snow. Afognak, Shuyak, Raspberryt and
several other adiacent i s I ands , i ncl udi ng northeast
Kodiak, have extensive coastal spruce forests.
b. Southcentral Reqion. In Ptr{S, deer cannot survjve
ffi coniferous forest along the beach
fringe, which provides essential shelter and forage
duriig the winter period (Reynolds 1979).
c. Southeast Regjon. Mature, o1d-groqt!- s.tands with a
@nopy intercept snowfall (Merriam 1971'
Jones !975., Weger 1977, Bloom 1978, Barrett 1979,
Harestad !979, tlUer and Raedeke 1980, Rose 1982, Walmo
and Schoen 1980, Kirchhoff and Schoen 1985). l|linter use
of forest stands has been correlated with high volume
(greater than 30 mmbf/acre) timb_er stands during
moderate to hard winters (Schoen et al. 1981, Schoen and
Kirchhoff 1983a). In milder winters' use is more
di spersed and i ncl udes I ower vol ume ( 1 ess than 30
mmbf/acre) (Schoen and Kirchhoff 1983a).
IV. NUTRITIONAL REQUIREMENTSA. Food Species Used1. Southwest Reqion. See table 1.2. ffiion. See table 1.
3. ffiDeer utilize a variety of forage species
@ year but prefer herbaceous forage when
avai'liUte. They substantia'l1y increase their use of
conifers, shrubs, and lichens when herbaceous species are
unavai lable (e.S. , under deep snow). Preference for
herbaceous species appears related proportional'ly to_ forage
quality. Winter is the period when forage availabi'lity is
most -
I imi ted and when two pl ant foods , bunchberry
(-Cornus cadadensil) and five-leayed UtqqUle (Rubus Pqdallls) 'aFE-fi-ighT@rred where available (Schoen and Kirchhoff
1983b, Schoen et al. 1982).a. l^linter (December-March):
1. Primary. Bunchberry and five-leaved bramble arepmiffi foods on Aimiralty and Chichagof - islands
under winter conditions of both 1 ittle snow
accumulation and of snow accumulation in open areas
with snow-free areas common under the canopy of an
2.
49
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2.
old-growth uneven-aged spruce-hemlock forest
(Schoen et al. 1983b,-Han'ley and McKendrick 1985).
Under the conditions of little snow accumulation,
fern-leaved go'ldthread (Coptis aspleniifolia) is a
-
primary food, as . is cedar
(Chamaecyparis nootkatensis), where it occurs on
CfiTh'asoTTilTnT-(Shffit a] . 1982). Under more
severe conditions of deeper snow accumu'lation and
persi stence, hem]ock (Tsuga spp. ) , arborea'l _ I ichens
(Usnea spp. and Al ecFia spp. ) , and bl ueberry(Usnea spp. and AlecJoFia spp.sffis- (Vaccinium ffi}e alsffis- (Vaccinium ffiie il so primary foods
(schoen TilRTrcnnot 1983b, Hanley and McKendrick
1985). 0n Prince of Wales Island, yellow cedar,
hemlock, blueberry, cedar (Thuia sPp. )., and
bunchberry are important winFfoods (Pierce
1eB1).
Secondary. Under mild winter conditions, blue-Sffipreading wood-fern (Dryopteris dilatata),
deeriiower (Tiirel l a trifol iaffiEr1ll6ffiea
( Ledum pal ustftTlsal mffifRubus spectabi'l i s ),
hemlock, and rockweed (Fucus fucus) are secondary
foods on Admi ral ty and -ehi-chagoF-l sl ands (Schoen
et a'l. 1982). During moderate-to-severe winters on
Admiralty and Chichagof islands (Schoen and Kirch-
hoff 1983b) and on Prince of Wales Island' mosses,
ferns, and ground I ichens are secondary foods where
b.
available (Pierce 1981).
Spring (April-mid June) :1. Primary. In the spring, bunchberry, five-leaved
Fam5lE, b]ueberry, devil 's club (Oplopanax-
horridus), skunk cabbage (Lysichiton americanum),
arsoreaT' I i chens , and ?eri:Teaveil goftffffil-Tre
primary foods (Schoen and Kirchhoff 1984, Hanley et
2.
al . 1984).
Secondary. Secondary foods are Aleutian heather
fPnvfmd;ce aleut'icai, western hem'lock (T{gq-
nffioor tea, and rockweed (Tanlev
et al . 1984).
c.Surmer (mid June-september) :1. Primary. In the sumner, bunchberry, five-leaved
6rami61E, skunk cabbage, devi I 's c'lub, and deer
cabbage (Fauria crista-gal I i ) are primary foods
(Schoin an?-TTFch-m1FF-T9-m5l-. A variety of other
foods have been reported eaten by deer (sunmary in
Habl ey et al . 1984) . Kl ei n ( 1953 ' 1965) al so
described deer cabbage, skunk cabbage, and sedges
(Carex biflora, Carex lyngbyel SPP., cryptorarpa'
and Carex macrochaeta) as the most important sumner
forage speETes.-
52
B.
2.Secondar.y.Secondaryfoodsareplantain.(Pla!-ffio maFitima), Sitk; vetch (Vicia gigantea), early
S]GbffiTfaccinium oval ifol ium), seaside gfrgw-o.iir- lrriffiswordfern (Poly-
i t i c rr u m "*tfi r-I-, ueT ch@ ra s. s ( E I vmu s a t9 n g r! a -
spF. mo].s . Pacific reed-gras:^--. (rya-
gi"bstlrnmKeeq-i:j, -(Kle-in 1e6i, 1e65)
e;ilUtneU-arry and Pacific reed-grass are wide-
spreld throughout Southeast Alaska'
Types of Feeding Areas Used
1. Summer/fal I :a. Southwest Region. (May-october). _I.n the Kodiak area'
ffiwiTloilffi' alder thickets, among
grutt-ihrub vegetation, and in alpine areas (h'igher than
i,ooo tt) (smith L979).
b. Sortt...i.it n.gId (May-0S1q!9I). The fo]1owing
irnima observations l;FfTlaTfine.-rcribe deer feeding
areas in Southcentral Alaska.
In P|^,S, deer feed a'long the margins of muskeg.openings
intersfersed withjn tlie c]imax spruce-hemlock forest
(ADF&G 1e76b).
0n islands that are large and high enough to-h.ave alpine
areas, deer feed on the abundant high-quality alpine
p1 ants .
Deer often frequent slide areas, which are especially
common in the alPine zone.
c. southeast Region (mid June-November). Deer range widely
? ident deer continue
to utilize lower-elevation winter range, while migratory
deer move to alpine and suba'lpine habitats (schoen and
Kjrchhoff 1985). A'lp'ine and suba'lpine habitat is
preferred during summer. clear-cuts are used but not
preferred, and -use of o.ld-g1_ow!h forest is extensive
isito.n ei a1. Ig7g, 1981). -Alpine areas are avoided in
fall (Schoen et al. 1981).
(For more detailed information on deer feeding areas.in
Southeist Alaska, which may apply to the rest of the
Alaskin- deer range, the reider is referred to Dr. John
Schoen's Pubf ished research.)
2, Winter:a. Southwest Reqiqn, (Septelqbe.r-Apfil ). Kodiak Island'
ffi occr.tr in grass-shrub thickets
composid of cottonwood, al der, qn.d_ wi I I ow; i n spruce
foresis; along windblown capes and bluffs with scattered
heath patchei; on steep i *indb.l own, and southerly
exposed' hillsides; near beach-timugl -fringes $yringsevere winters; ind within jntertidal areas (Smith
1e7e).b. Southcentral Region (November-Apri-l ). Winter feeding
areas ited than in the
53
remainder of Alaska's deer range because a higher
proportion of land is muskeg, the timberline is'lower,
ind.the beach-fringe area is narrov{er (ADF&G 1976b).
Deer remain just below the snow'line, moving up or down
with the changing snow depths (Reynolds 1979). When
snow depths increase and preferred evergreen forbs
become unavailable, deer are forced to lower elevations
to feed in the coniferous forests adiacent to beaches.
Shishido (1984) found that deer use the forest's edge
more than its interior. If snow depths increase and
beach-fringe feeding areas become depleted, deer are
forced to feed on the beaches (iUia.1.
During a winter of extremely mild snow conditions'
Shishido (1984) noted that mountain hem'lock forests
(where at least 50% of the net timber volume is mountain
hemlock) in Pl,lS received more deer use than the spruce,
western hemlock, or spruce/western hemlock forest types.
However, Shjshido points out that when the mountain
hemlock component of this forest type is beyond 50% of
the net timber volume, deer use may decline rapidly
because of the more closed canopy. The transition
forest type, a mix of western hem'lock, mountain hemlock,
and Sitka spruce, found in marginal or extreme site
conditions (such as along muskeg edges or beach fringe
stands), was also used heavily by deer.
Shishido (1984) reported that deer preferred to use
stands with a relatively low tree basal area (and,
therefore, with an open tree canopy), large amounts of
Vaccinium spp. stems and Coptis.asplenifolia biomass, a
hEEFogeneoi,rs canopy struffi(usuaTfJ, associated withheterogeneous canopy structure
uneven-aged old growth forest), and relatively greater
net timber volume.c. Southeast Region (Decembgr-March). 9ptimum deer winter
iange consffi (greater than 30
mmbf/acre) o1d-growth stands on productive, well-drained
sites with 1arge, irregularly spaced trees and abundant
bunchberry, bl ueberry, salmonberry ( Cornus-Vac-
cinium-Rubus) understory (Schoen et al. lg$Ia, Schoen
;rnd'ffi-hhoff 1983b). winter use is correlated with
Vaccinium, Cornus, and Coptis (Rose 1982). Dispersal offfi[reiF-iluring frTlllTinters, with greater use of
low-volume ('less than 30 rmnbf/acre) timber stands
(Schoen and Kirchhoff 1983b). Use of regrowth stands of
0-147 years is proportionately low (Wallmo and Schoen
1980, Rose 1982). Low-e'levation (1ess than 1,000 ft)
old-growth forests are preferred, whereas clear-cuts,
muskegs, and upper forest areas that accumulate deep
snow are avoided (Schoen et al. 1981, Schoen and
Kirchhoff 1983b).
54
c.
3. Spri ng:a. 5outheast Reqion (Aprjl-mid June). 0n Annette Island'
(3 to 25 Years old)
snow-free clear-cuts during spring. Schoen et al.
(1981a) and Schoen and Kirchhoff (1983b) -observedradio-col lared deer using a variety of o1d-growth
stands, including low-volume sites, during spring.
Factors Limiting Availability of Food
1 . Wi nter. Excess i ve snowfa I 1 ( deeper than 25-30 cry) can
prevent deer from obtaining critical food resources (Hanley
1984, Reynolds 1979). Snow is the major factor limiting
avaiiabiiity of forbs (Jones 1975, Weger 1977, Bloom L978'
Harestad |ilg, Barrett L979, Schoen and Wallmo 1979, Schoen
et a'|. 1981b, Rose 1982, Schoen and Kirchhoff 1983b).
Overstory characteristics determine snow interception !.yforest stands (Jones L975, Bloom 1978, Harestad and Bunnell
Ig7g, Kirchhoff and Schoen 1985). Snow is substant'ia11y
deeper in muskegs, clear-cuts, and other o_qe_n areas than-in
o'ld-growth foreits (Merriam 1971, Bloom 1978, Barrett 197.9'
Scho6n and Wallmo 1979). Hjgh-volume old-growth stands with'large, irregularly spaced trees provide an oplimyl.winter
naUitit bedause - of the quantity and availabi'l ity of
nutritious evergreen forage under severe winter cond'itions
(Schoen et al. 1985, Kirchhoff and Schoen 1985).
Harvesting old-growth by clear-cutting results in reduced
forage aviilability even where or when snow accumulations do
not limjt availaUitity. Clear-cuts (0 to 30 years o1d) are
characterized by high understory plant biomass, with the
major component- be'ing shrubs (Alaback 1982). Second-growth
stinds (30 to 150 years o1d) have depauperate, unproductive
understory vegetation (Jones 1975, Robuck I975, Alaback 1980,
Wallmo ani Scfloen 1980, Schoen et al. 1981b, Alaback 1984).
Silvicultural thinning of second-growth stands maintajns a
more open canopy and may increase understory productiYitv.
Silvicultural obiectives may be'incompatib'le with habitat
improvement, however, because maintaining lower timber Stand
dehsity may conf'lict with silv'icultural obiectives of ful I
site util ization for timber product'ion (Harris and Farr
1979). The degree to wh'ich improved understory production is
negaied by increased snow accumulation in thinned stands is
not known (Kessler 1982). Alaback and Tappeiner (1984) found
general'ly poor and variable understory response . to
precommercia'l thinning after f ive-to-seven, years' .y'ith
iroductivity often decreasing at the expense of tree-seedling
lroductivity. Secondary hemlock canopies. appeared to. be.one
l.esult of thinning that is I ike'ly to shade out understory
species. Stands thinned at varryi.ng intensit'ies on Heceta
Iiland were simi'lar'ly unproductive (Kessler 1982)
Logging slash can also limit food availability. The-effects
ot-itaitr and deep, soft snow in limiting food availability
and increasing en'ergy requirements for locomotion are similar
55
D.
and can be additive (Parker et al. 1984). The depth and
amount of 'logging slash and regrowth shrub biomass have'
interactive effects (i.e., each exaggerates the effect of the
other) . As l oggi ng sl ash i ncreases and the 'l eve'l of shrub
biomass increases over that which is optimal for access to
portions of the summer range, the difference between energy
expenditure for foraging and resu'ltant energy intake per unit
of expenditure increases (Hanley 1984.)
Low coastal winter ranges may be depleted when population
densities increase as a result of a trend of several years of
mild winter weather (Reynolds 1979).
An intensjve logging program creating extensive c'lear-cuts
cou'ld reduce food accessibility because of the resultant
greater snow depths in the clear-cuts attributable to the
removal of the forest canopy (ibid.).
Competition with cattle and elk can lead to winter range
detbrioration (Erickson 1958).0il contamination of kelp on critical winter beaches could
remove a life-sustaining food item (Reynolds 1979).2. Spring. Persistence and depth of snow cover, reduced
pFoductiv'ity of forage in even-aged stands, and logging slash
deposition affect food availability, as described for winter
condi ti ons.3. Sununer/fall: Logging slash can restrict access to forage
FErnts_lxan-tey et a]. 1984, Wallmo and Schoen 1980).
Factors Affecting Qua'lity of Food1. Late fal l/winter. Vaccinium oval ifolium growing under
@itions have hi@Frct-e-in values than in
clear-cuts (Bi1 lings and Wheeler L979). The qua'l ity of
Cornus canadensis was highest in high-volume o1d-growth
ffiasT stand's,-Titermediate in low-volume old-growth forest
stands, and lowest in clear-cuts in late fa'11 (Schoen and
Kirchhoff 1984). Many plants remain green under matureforest canopies during winter. Herbaceous p'lants and
evergreen forbs are highly digestible compared to hemlock andto deciduous shrubs. Usnea spp. lichins are also highly
digestible but have 1ow protein content (Schoen and Wallmo
reTe).2, Spring/sunmer/early fall. Long photosynthetic periods andresult in high nitrogen levels in
al pi ne vegetat'ion. Pl ants i n ear'ly growth stages are most
nutritious. Topographic variation affects plant phenological
succession. The degree of topographic variation inf'luences
the extent and location of variation in nutritional values
over the growing period, with a high degree of topographic
variety resulting'in high-quality forage being available over
longer periods (Klein 1979).
Feeding Behavior1. Movements. Deer make elevationa'l movements seasona'l1y in
response to snow conditions and forage availability (Barrett
E.
56
7g7g, Schoen and Kirchhoff 1985). Elevational movements can
U. hampered by the presence of clear-cuts adiacent to beach
fri nge' habi tai ( Schobn and Ki r chhoff 1985) -
Deer populations have both migratory.ard resident components'
with hi'gratory animals residing at higher elevations during
al I seaions ( ibid. )
2.Use of edge. Deer do not
hE'b'iffi--TFlween cl ear-cuts
increase winter use of edge
and o1d-growth hab'itat tYPes
V.
(Kirchhoff et al. 1983)
3. Snow conditions. Deer will pass through 12-to-18 inches of
snow-(to ffi-n ferns) (smith 1979).
REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat
1.'southwestRegion.BecausedeeronKodiaklslandareusually?tnlnd -mffi-Tevel to 1,000 ft during 'late May/early June,
one could assume that they give birth at relatively low
elevations in heavy cover (Smith 1984).
2. iouthcentra'l Region. The ADF&G (1976a) reports lhat fawns
are usuaTlfioin Tn fri nges of trees adiacent to I owl and
muskegs or beaches.
3.South6ast Region. Fall habitats of migratory and resident
mugh to provi de regul ar. geneti c i nterchange
(iir'o.n -anJ' ri rcnn'ott 19b5) . Deer
- elrri !.i ! i ncreased use of
muskeg habitats during the rut in fall (ibid')'
Reproductive Seasonal i tY
Tht bieeding season degins at mid 0ctober and peaks in mid
November, with fawns born in late May to early June.
Reproductive Behavior
gutks are polygamous and establish dominance by mild pushing con-
l;aia, antier-flresentation, pawing, and stamping. From 0ctober to
llu".tt, temales are receptive to bieed'ing for ?! to 36 hours during
estrui. The estrus cyc'le of female deer is 24 to 28 days and^may
U.-..p.uted several iimes if conc-eption 9o..t not occur (ADF&G
fgZOu).- Bucks incur large weight losses- dur.ing the rut, and by
December their fat reserves are often depleted.
Age at Sexual MaturitY
M6st does breed at 1.5 years (tfreir seasonal fall). The quantity
and quality of availabli forage can affect the age at whjch they
first breed (Cowan 1956).
1. Southeast Alaska. In general, fawns and older female does do
ffin1e85).Litter Size/PregnancY Rate
Data describing-'littbr size are not available for Kodiak or PWS.
1. Southeast-A'laska. Female fertility rates are considered to
ffi those of Columbian black-tailed deer
(0docoileus hemionus columbianus) on Vancouver Is'land; the
impEmis Ttss feffil arul-aTtains maximum ferti'lity more
slowiy than other deer species (Thomas 1983).
B.
c.
D.
E.
57
In-utero pregnacy rates are generally high, averaging nearly
two fetuses per adult doe in areas on Admiralty and Chichagof
islands (Schoen et al . L982; Johnson 1985).F. Gestation Period
The average gestat'ion period is 203 days, with a range of 183 to
2L2 days (Cowan 1956).
VI. FACTORS INFLUENCING POPULATIONSA. Natural1. Winter severitv (temperature, fr
sw e most significant
regulating factor on deer populations (Merriam 1968, 1970,
1971; Jones 1975:' Taber and Hanley 1979). Starvation
accounts for 80% of winter mortality, with fawns and animalsin age classes over five years old comprising the bulk of
morta'lity and a higher proportion of fawn losses on ranges in
good (vs. heavi ly used ) condi ti on (K'lei n and 0'l son 1960) .
Main'land deer populations, though seldom as high as island
populations, are more static than island populations,
probably due to uniformly more severe winter conditions and
mortality factors (01son 1979).2. Avai l abi l i ty and quqqtr ty of cri ti ca] o wth wi qtqr
o1@owth forest i s a factor that 'l im'i ts deer popul ati ons
(Hanley 1984, Schoen et al. 1985).3. Quantity and quality of surrner range. Winter survival also
tieer to accumul ate fat duri ng
summer (Ragelin 1979). Surmer range condition and extent is
a primary factor affecting the size of animals, population
densities, and the age structure of the population. Primary
factors inf'luencing the quality and quantity of available
deen forage are the degree of altitudinal and topographic
variation and the rel ative proportions of al pi ne and
subalpine areas over the range of a population (K'lein 1963,
1965, 1979).4. Predation. Predation by brown bears,. wolves, black bears,
ai'iloyotes can reduce deer numbers (ADF&G 1976b, Reynolds
1979). hlolf predation can reduce numbers and delay
population recovery fo'llowing heavy winter losses on larger
islands or on the mainland and is considered a factor that
can accelerate population trends (Merriam L970; Jones and
Maser 1983; Van Ballenberghe and Hanley, in press). Wolves
were introduced on Coronation Island, a small previously
wolf-free island, where they reduced the deer population to a
very low level (Merriam 1970). The retention of "islands" of
deer winter range surrounded by clear-cuts and regrowth could
result in concentrating deer during severe winter conditions
and making populatjons more vulnerable to predation (Schoen
et al. 1985).
5B
5. Djsease. Disease is not considered a limiting factor on deer
E$fiilarrce (ftein and 0lson 1960, Klein 1965, Merriam 1970).
Lungworm infections, however, can be a significant morta'lity
factor for fawns and is thus a population-regu'lating factor
6.
7.
(Johnson 1985).
iompetition. Competition with elk for available winter range
can*Iim-iTTeer poirulations (Taber and Raedeke 1980)
Habitat deterioration. Habitat deterioration due to natural
ffiarthquakes, fires, and landslides can
remove important areas of habitat (e.9., beach-fringe timber'
which is valuable winter range).
Human-rel atedA Summary of possible impacts from human-related activities
includes the following:o Alteration of habitato ' Reduction of food supPlYo Harassment resulting in disturbance/displacemento Barriers to seasonal movements
" Competition for available winter range with cattle
" 0verharvesto Predation by domestic dogso Pollution of water and/or food supp'ly
(See the Impacts of Land and Water Use volume of this series for
idditional information regarding 'impacts. )1. Southeast Reqion. The proiected effects of clear-cut logg'ing
@ns are a result of 1) significant reduction
of forag'e supplies and impeded access to deer for one to two
years itter clear-cutting, 2) reduced summer use of
clear-cuts from 4 to 15 years due to dense shrub growth and
residual s'lash, 3) reduced Summer use of clear-cuts from 15
to 30 years due to closing of stands, shading out of forbs'
and dense shrub production, 4) reduced summer use for
approximate'ly 160 to 200 years due to shading out of. forage'
and 5) reduced winter use of clear-cuts and regrowth stands
through the length of a timber rotation due to h'igh.snow
accumulations in open clear-cuts and lack of wjnter foods in
c'losed regrowth stands for approximately 160 . to 200 years
(Schoen and l,Jallmo 1979, Wallmo and Schoen 1980)
In summary, "secondary succession of western hemlock Sitka
spruce foiest in southeast Alaska depicts a 15 to 20 year
pbst-'logging period with abundant but largely in-accessible
iorage,-followed by perhaps two centuries of usable habitat
with-sparse foraget' (Wattmo and Schoen 1980). Schoen et al.
(1985) have developed a model to predict relative changes in
deer populations resulting from planned timber harvesting-in
Southiast Alaska with a 100-year rotation schedule.
Reductions of deer populations below 50% of current levels in
74% of drainages to be logged are predicted at the end of the
planned rotation.
B.
59
Deer densities and harvests have declined up to 75% in.
drai nages on Vancouver Island fol'l owi ng 1 ogging (Hebert;
1979). Deer popu'lation declines of 25 to 75% are projected
in western Washington in areas slated for intensive logging
within the next 5b years (Taber and Raedeke 1980). Schoen
et al. (1981b) suggest that ear'ly theories that deer
responded positively to logging of o1d-growth throughout
North America were based on inadequate data or fau'l ty
assumPti ons.
VII. SPECIAL CONSIDERATIONS
Deer populations are often geographically isolated on small islands.
Elk transplants are being proposed for the Southeast Region. El!
compete fdr many of the same food plants as deer in other areas of
Alaska. Retention of only small areas of critical deer winter range
from logging could result in overbrowsing of these areas, concentration
of predation, and reduction of carrying capacity during severe winters
(Schoen et al. 1982).
VIII. LEGAL STATUS
See the Human Use section in the Alaska Habitat Management Guide for
the Southcentral Region.
IX. LIMITATIONS OF INFORMATION
Because deer populations have been moderately high and are stil l
expanding in Southcentral Alaska, the need to gather basic biologic_a1
data on-deer in Southcentral A'laska has been difficu]t to justify.
Quantitative data describing deer d'istribution and abundance, habitat
use and requirements, food habits, and reproductive activities in
Southcentral A'laska are therefore lacking or minimal.
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64
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9o pp.
Thomas, D.C. 1983. Age-specific fertility of female Columbian black-tailed
deer. J. Wi1d1. Manage. 47:501-506.
Van Ballenberghe, V., and T.A. Hanley. In press. Predation on deer in
relation to old-growth forest manigement._in Southeast Alaska. In M.R.
Moehan, T.R. Merrell, Jr., anO- f .n. Hanley, ed.s-. Fish and wTIOtite
relationshipt in oli-growth forests. Pioceedings of a symposium
(Juneau, Alaska, 12-15 APr. 1982).
Wallmo, 0.C. 1981. Mule and black-tailed deer on North America. Lincoln:
Univ. Nebraska Press.
wallmo, 0.c., and J.w. schoen. 1980. Resp_onse of deer to secondary forest
succession in Southeast Alaska. For. Sci. 26:448-462.
Weger, E. Ig77. Evaluation of winter use of second-growth stands by
black-tailed deer. M.S. Thesis, Univ. British Columbia' Vancouver.
42 pp.
65
Caribou L,:ife History and Habitat Requirements
Southrest and Southcentral Alasha
a 'z'..g :.vLe
Map 1. Range of caribou (ADF&G 1973)
I. NAMEA. Conmon Name: Caribou, tuntu (Yup'ik), veiex (Denaina)
B. Scjentific Name: Rangifer tarandus granti (Banfield 1961)
I I. RANGEA. Statewide
Caribou are distributed throughout Alaska except on the
Southeastern Panhand'le and a'long the Gulf of Alaska coast from
southeast Alaska to the Alaska Peninsula and most offshore
islands (Henming 1971).B. Regional Distribution Summary
To-supplement the distribution information presented in the text,
a series of b'luelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale,
67
but some are at 1:1,0001000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition'
a set of colored 1:1.,000,000-scale index maps of selected fish and
wild'life species has been prepared and may be found in the Atlas
that accompanies each regional guide.
1. Southwest. Four distinct herds exist in Southwest Alaska:
TfiET6-rthern Alaska Peninsu'la, Southern Alaska Peninsula,
Mul chatna , and Adak herds ( Sel I ers , pers . comn. ) The
Northern Alaska Peninsula herd ranges from the Naknek River
south to Port Moller. The Southern Alaska Peninsula herd, ranges generally from Herendeen Bay south to and including
Unimak Island (Hemming 1971). The Mulchatna herd ranges in
an area generally west of the Alaska range, Iliamna Lake, and
the Kvichak River to the lower Nushagak River, throughout the
upper Nushagak River country, including the King Salmon River
drainage, and as far north as the Tay'lor Mountains and Stony
River (Tay1or, pers. comm. ) (for more detailed narrative
information, see vo'lume 1 of the Alaska Habitat Management
Guide for the Southwest Region.)2. Southcentral. There are three caribou herds that occupy the
ffittceniFti- Region year-round. The largest, the Nelchina
herd, occupies the upper Copper, Ne'lchina, and Susitna river
basins. The Mentasta herd ranges along the northwest slopes
of the Wrangell Mountains and the headwaters of the Copper
River. A small herd of caribou occupies portions of the
Kenai Peninsula, having been transp'lanted there in the mid
1960' s . Thi s herd i s composed of two rel ati ve'ly di sti nct
subherds. The Kenai 'lowlands herd utilizes the muskeg areasin the vicinity of the Kenai airport and the Moose River
F'lats. The Kenai Mountains herd occurs in the northern Kenai
Mountains south of Hope, between the headwaters of
Resurrection Creek and the Chickaloon River. The Mt.
McKinley herd seasona'l1y occurs in the Southcentra'l Region
during calving and winter (ADF&G 1976). (For more detailed
nariative information, see volume 2 of the A'laska Habitat
Management Guide for the Southcentral Region. )
III. PHYSICAL HABITAT REQUIREMENTSA. Aquat'ic
During summer, caribou tend to concentrate their feeding activity
in moist boggy areas where sedges (Carex spp. ) predominate.
During wintef, aquatic vegetation such as sedges and horsetails
(Equisetum spp.) are heavi'ly used along lake margins and streams.
MGIT[:E-pushups, which consist of a variety of aquatic vegetation,
supply i substantial food source to wintering caribou (Skoog
1e68).B. Terrestrial Cover Requirements
The use of ridge tops, frozen lakes and bogs, and other open areas
for resting is a learned behavior related to predator avoidance
68
that may have resulted from wolf-caribou interactions. The
caribou'i apparent reluctance to enter riparian w'illow (SaliI
spp. ) stands' and other heavy brush cover and its state of
alertness when passing through such area_s suggest.that caribou
associate such cover "witn aftacks by wolves -and bears (Miller
1e82 ) .
During the spring calving period, caribou tend to occupy oPel
terrain with gentie slopei affording a wide field of view, wh'ich
again may be r:elated to'predator avoidance (A0f&G f976)
Diring ium*er, caribou'make extensive use of windswept ridges'
lingeiing snow drifts, glaciers,_gravel bars, and elevated terrain
to avoid-insects (Skoog-1968, Kelsall 1968, Hemming 1971, Bergerud
1978, Miller 1982).
IV. NUTRITIONAL REQUIREMENTSA. Food Speiies Used (from Skoog 1968, unless othertlise noted)
1. Ii"ter (miO OitoUer to ft ). Lichens are utilized when
a fruticose l ichen - sPecies
relative to palatability, abundance, and use _ include the
following: Ciadqnia al.-pestfis,.9. ra{rgifelil'3-' 9' :4Y1!iT.:c.. mitis,-.a1Fletraria nivalis, plus vari0us spec'les or
arborea I | 1 cnens -FForn-tnE-genera Al ectori a, Everni a, and
Usnea.
midrl2.ril to mid June) and Summer @re is a contlnuousAUgUSt). DUring Spflng and SUmnef' f,nere ls d sulrLrrruuu5pi66; of shifiinb to plant species that. are apnpggnils
itrenot ogi cal growtft st_ages _ r'i ch i n avai I abl e nutri ents .
Various- grass-es (mostly Festuca altaica, . Cala,mggrgstis
canadensi i, and Hi erocbl clq aTpTna )-and-se@s tnSlF'fy-g
STqeTofilt- C. miln[Enaffi,T-podocoralpq, and Eriophorum
.+i-vaqinatum) are a irrl nfiv-@fgetation-efrrare
useo exf,ens.rvery. ifre catk'ins of willow (espec'iqllV S]tx
alaxensis, S. pianifqljg sSP., pulchra, and S.- gl?uca) are
ffib fn.Ti756*n growth-aE6-6d used. -As-The season
oroqressei the lelves o? willow, resin birch (Betula
btaiautosa). and dwarf birch (8. nana) are used extensively
tuFing--Tuiid and July. Many -sp6-cies of sedge and grass
(espeii at ty those of the genera -4l.opecrfqs , Arctggrosti s 'Dupontia, Festuca, Poa, Puccinellia' Calamagrostts' ano
Uiffi-oe ) , Toi6-j, ilnd- horseraTT-s are -ffid--ExGfrTi vely ,
Aepending 'upon their growth stage,- annual .differences in
weith"r,-and the partiCular area being used_ by the caribou.
Legumes are especially important; sp-ecies of. particular note
'inilude Astraqalus uirbeliatus, Lupinus arcticus, Hedysarum
alpinum, @cens. The herbs Gentjana
qTauca , Swerti a perennl s , and-Sedum roseum are--tr-i!F[
palatable.btner species known to be grazed_ incl.ude Antenlqriq
*ono..pn-iru, -- Ariemisia arctici, Epilobium TriTTEIfi;
69
B.
Pedicularis spp., Petasites frigidus' Polygonum bistorta'
Turnex affi cu s',' and TETTilra ga s pp .
SlrF-ing-Taffi[]nmer, musfirooms (especially those of the gemus
Bol etus ) may be eaten extens'ive'ly when avai I abl e.
Throughout the spring and sumner' caribou wi'll continue to
bake small quantities of lichens, dried plant parts, stems,
and evergreen parts.3. Fall (mfd August to mid gctobel). During the fall, the
V of the summer forage
decreases, and the caribou's diet gradually shifts toward the
more restrictive winter forage. The leaves of willow are
heavily utilized as long as they are availab'le. Grasses and
sedges are eaten throughout the fa1l period. Lichens are
increasingly used as the fall progresses. Carex aquatilis'
which lin6s- the shores of lakes, p6nds, and TTougns, apfars
to be an especially favored food item.
Types of Feeding Areas Used
1 . Wi nter. Dependi ng on the ava i I abi 'l i ty and I ocati on of
TaSlTa't, spruce forests ( primari ly spruce/l i chen associ -
ations), bogs, and lake shores are used extensively (ADF&G
1976). 0n the Alaska Peninsula's poorly drained coastal
plains, areas where sedges are abundant are used (Henming
1e71).2. Spring. Migrat'ion to calving areas occul"s _during !lltpeFToa', and the types of areas used can be highly variable,
depending upon the spring melt and green up. During some
years, there is a quick migrationa'l transition from wintering
cal vi ng areas. As soon as spri ng p1 ant growth begi ns ,
caribou switch to areas where early growth species occur
(Lieb, pers. comm.).3. Surrner. Areas of use consist primarily of treeless uplands
m'ere heath tundra , al pi ne tundra, and sedge wetl and
associations dominate. In response to insect harrassment,
caribou frequently use wind-swept ridges (ibid.).
4. Fall. Carjbou remain on or near summer ranges until the
qu'antity and qua'lity of forage significantly decreases and/or
weather forces them to begin migration toward the wintering
grounds (Henrming 1971). Because fal 1 migration genera1 1y
occurs during this period and feeding often occurs on the
move, it is difficult to relate specific feeding locations to
this period (Skoog 1968).C. Factors Limi ti ng Avai I abi I 'ity of Food1. t,{i nter. Snow depth of 50 mm (20 i nches ) i s general ly
EiElllered the upper limit for use of areas by caribou. Ice
crust of 4 to 6.5 cm (1.5-2.5 inches) on top of the snow is
considered the upper limit caribou can paw through to obtain
food (Pruitt 1959, Skoog 1968, Pegau 1972' LaPerriere and
Lent 1977).2. Spring. Ca'lving area selections by_ caribou have been, in
paFt, attributed to early snow-mel t and the consequent
70
V.
availability of new vegetation (Lent I979). Should .a late
snow-mel t 6r a I ate snowstorm occur, use of otherwi se
preferred eirly green-up vegetation may be restricted (Skoog
1e68).3. Summer. Insect harassment can restrict caribou feeding by
Gffig them to move about constantly-or gccupy ale-ls such as
snowdrffts, where food is unavailable (Skoog 1968' Miller
1e82).4. Fall. Increasing frost and/or snow in the high country
ffiease the quanti ty and qual i ty of forage , i fl part
triggering fa1I migration (Skoog 1968).
D. Feeding Behavior1. |lJinter and fall. Feeding general'ly occurs during. the mid
ffi day and-night. Caribou prefer-the finer
iarts of p'lants, s-uch as the upper portions ..of 'lichens'
ieaves and'stem fips of sedges and grasses, and the stem t'ips
and buds of wi I I'ows. Th;i r curiory grazi ng habi ts he1 p
reduce the possibility of localized overgrazing the range
(ibid.).Z. ipri.i: Feedjn_g_ behavior is sim1lar to winter, with an
increased use ofleaves of willow and dwarf birch (ibid.).
3. Summer. Caribou select p'lant^-species according to the
o.cr...n..-of g...ning 'leaf'and flower buds (ibid.)- Feeding
occurs through-out the day, but because of insect harassment
most feeding" takes place during the cooler twilight hours
(Mi'ller 1982).
REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat1.' Breeding areas. The rut usually takes place durin-g fall
ffia-issomet.imesaccompaniedby.apauseorslowdown
B.
c.
of movement. Breeding usua'l1y takes p'lace in areas above
timberline (Skoog 1968), although this has not been the case
during most recent years for the Nelchina herd (Pitcher
I e84)2. Parturition areas. (See III.b., PHYSICAL HABITAT REQUIRT-
ffi, NUiRITI0NAL REQUIREMENTS, spring.)
Reproducti ve Seasona'l i tY
1.' Breedjng. Breeding seasonal'ity varies in different parts.of
ihffifUou range. In centrai and southern Alaska, caribou
breeding occurs- primarily during the first two weeks of
0ctober (ib'id.).
2. Parturition. Parturition genera'l'ly occurs from mjd May
th-roughTa f i rst week of June ( i bi d. ) .
Reproductive Behavior1.' Breedi nq. Bul I s do not gather harems but rather ioj n
e[ifiTnf bands of cows and ybung, One or-more bul]s tend to
become iominant within the band, depending on the- size. of
the group (ibid.). As the rut peaks., dominant bulls reduce
theii tora!ing markedly, concentrating instead on tending
71
estrous females. Copulation is brief and generally occurs at
dawn or dusk (Espmark 1964). By the end of the rut, rutting
adult bulls have depleted their fat reserves and enter winter
in lean condition (Skoog 1968).2. Parturition. According to Lent (1966), Ke]sal'l (1968), and
Sko-og-lJF8), cows do not actively seek isolation to give
birth. Bergerud et al. (.|984), however, indicated that
cari bou in Spatsizi Provincal Park, Briti sh Columbia,
dispersed to high south slopes in mountains for calving as an
antipredator tactic. The mother-young bond is initiated
within the first minutes of the calf's life and is necessary
for the survival of offspring during the first six months of
I ife (Mi1 ler 1982).
After calves are mobile, "nursery bands" of cows and calves
are formed (Pruitt 1959). In central Alaska, most cows do
not regroup or join mobile bands until their calves are older
than two days (Skoog 1968).D. Age at Sexual Maturity
Most cows conceive at 2.5 years of age. A few will conceive at
1.5 years, however, if in good condition. Bulls are fertile at
1.3 to 2.3 years of age (Skobg 1968, Dauphine 1976).E. Fecundity
Adult fema'les of 2.5 years old and older have pregnancy rates of
about 80% and produce one offspring per year. Feamalqs 3.5 years
o'ld and older have pregnancy rates of about 90% (Skoog 1968,
Miller 1982).F. Gestation Period
Gestation takes 225 to 235 days (Skoog 1968, Bergerud 1978).G. Lactation PeriodLittle is known about the actual weaning process (Miller 1982).
Kelsal'l (1968) concluded that weaning must occur during July
because biting insects wou'ld greatly disrupt nursing after July.
Skoog (196S), however, suggested that weaning takes place between
September and December and most'ly occurs prior to November.
VI. FACTORS INFLUENCING POPULATIONSA. Na tu ra'l
Emigration, which may be density-re'lated, can cause large
fluctuations in herd sizes. Weather, particularly precipitation'
co'ld, and wind, are a deadly combination for newborn calves, often
resu'lting in hypothermia (Banfield .|954). Wolf and bear predation
in some aneas can be an important factor in population control
(Skoog 1.968, Bergerud 1978, Miller L982, Gassaway et al. 1983).
Fire has destroyed 'large expanses of winter range but in fact may
not cause major fluctuations in population numbers because of
shifts in habitat use (Skoog 1968).B. Human-rel atedA surmary of possible impacts from human-related activities
i ncl udes the fol 'l owi ng:o Competition with introduced (wild or domestic) animals
72
o Alteration of habitato Harrassment, active and Passiveo Barriers to movement, physical and psychologica.l.
" Overharvest, expeciaily-when associated with high predation
rateso vegetation damage/destruction due to air po]lution
(See thil Impacts of-Land and Water Use volume of this series for
iaaitional information regarding impacts.)
VII. SPECIAL CONSIDERATIONS
Food suPPlY, PoPulation densitY'
man, and a varietY of other factors
seasonal ly and perhaps for several
VIII. LEGAL STATUS
The Alaska DePartment of Fish and
caribou. See the Human Use section
managerial considerations.
IX. LIMITATION OF INFORMATION
Because .uiiUo, are nomadic and therefore occupy varjous kinds of
habitat at different times, it is difficult to accuratel_y describe
caribou hab.itat requirements. Causes of large-qopulation -fluctuationsin runy instances are also still unclear. Final'ly, thq effects of fire
on caribou habitat and distribut'ion are not clearly understood.
REFERENCES
ADF&G. Ig76. Alaska's wildlife management p1ans, Sou_thcentral Alaska: a
public proposal for the management of Alaska's wildlife. 291 pp.
Banfield, A.l\|.F. .|954. Prel iminary investigation of the barren-ground
caribou. Can. tlJild'|. Serv. |r1iidl. Manage. Bull., Ser. 1, No. 108.
112 pP.
. 1961. A review of the re'indeer and caribou genus Rangifer. Nat.
-ffi.
Can. Bul'l . 177, Bio. Ser. No. 66. 137 pp.
Bergerud, A.T. 1978. Caribou. Page.s 83-101 in J.L. Schmidt and D'L'
Gi I bert, eds . Bi g game of tloitfr Ameri ca :-ecol ogy and management.
Harrisburg, PA: Stackpole Books. 494 pp.
Bergerud, A.T., H.E. Butler, and D.R. Miller. .|984. Antipredator tactics"-oi 'calv'ing -ii.ibout 'dispersion in mountains. Can. J. Zoo. 62(8):
1 ,566- 1 ,575.
1g74. Nelchina and Mentasta caribou reports. Vol. 2., proi.
rept. Projs. t||-17-5 and hl-17-6, Job 3.1 (S&I) and final rept.
W-17-6, Job 3.2 (S&I).
weather, snow conditions, insects'
can alter caribou movement patterns
years (ibjd.).
Game has manageria'l authori ty over
for a more detai'led description of
G. N.
prog.
Proj.
Bos,
73
Dauphine, T.C., Jr . 1976. Biology of the Kaminuriak population of barren-' ground caribou. Part 4: Growth, reproduction, and energy reserves.
Can. t'Jildl. Serv., No. 38. 71 PP.
Espmark, Y. 1964. Rutting behavior in reindeer (Rangifer tarandus !.).
Anim. Behav . L2:420'426.
Gasaway, 1.l., R. Stephenson, and J. Davis. 1983. }lolf/prey relationships in
interior A1aska. ADF&G, Fairbanks. 15 pp.
Hemming, J.E. 1971. The distribution and movement patterns of caribou in
Aiaska. ADF&G Tech. Bul'l . 1. Juneau. 60 pp.
Ke]sall, J.P. 1968. The migratory barren-ground caribou of Canada. Can.
l{ildl. Serv., Wildl. Manage. Bull. 3. 340 pp.
LaPerriere, A.J., and P.C. Lent . 1977. Caribou feeding sites. in relation
to snow chaiacterjstics in northeastern Alaska. Arctic 30(2):101-108.
Lieb, J.l.l. Personal communication. 1985. Asst. Mgt. Biologist' ADF&G,
D'iv. Game, Gl ennal I en.
Lent, P.C. 1966. Calving and related social behavior in the barren-ground
caribou. Zeitschrift fur Tierpsychologie 23(6) :70t-756.
. 1979. Synoptic snowmelt patterns jn Arctic Alaska in relation to
Tibouhabitdtuse.Pages77-77inE.Reimers,E.Gaare,andS.
Skjenneberg, eds. Proceedings of t-he second international reinde-
erlcaribou symposium, Roros, Norway. 799 pp.
Mil'fer, F.L. 1982. Caribou. Pages 923'959 1n J.A., Chapman and G.A.
Fi'ldhamer, eds . t,li I d manma'l s of North Amerita. Bal timore and London :
The Johns Hopkins Univ. Press. 1,147 pp.
Pegau, R.E. L972. Caribou investigations - analysis of range. ADF&G, Fed.
Aid in Wildl. Rest. Proi. W-17-3. Juneau. 216 pp.
Pegau, R.E., G.N. Bos, and B.A. Neiland. 1973. Caribou report. ADF&G'- Fed. Aid in wi'ldl. Rest. proi. prog. rept., Proj. |/.-I7-4, Jobs 3.3R'
3.5R, and 3.8R (2nd ha'lf) and 3.9R; and Proi. w-17-5, Jobs 3.3R,3.5 R'
3.8R, and 3.9R.
pitcher, V.1,1. .|984. Caribou. ADF&G, Susitna Hydroelectric Proiect ann.
rept. Vol. 4: Big game studies. 43 pp.
Pruitt, W.0., Jr. 1959. Snow as a factor in
birren ground caribou (Rangifer arcticus).
the winter ecology of the
Arcti c L2(3):159-179.
Area Mgt. Biologist, ADF&G,Sel'lers, R.A. 1983. Personal communication.
Div. Game, King Salmon.
74
Skoog, R.0. 1968. Ecology of the c-arib-ou . ([angife=!^tarandus granti ) in'A]aska. Ph.D. Dissert., Univ. Cal ., Berkeley. 699 pp.
Taylor, K.P. 1984. Personal communication. Area Mgt. Biologist, ADF&G'
Di v. Game, Di I 1 i ngham.
75
Dall Sheep Life History and Habitat Requirements
Southcentral Alasha
I.
Map 1. Range of Dall sheep (N'ichols 1978a, Heimer and Smith 1975)
B. Scientific Name: Ovis dalIi
NAMEA. Corrnon Name: Dall sheep, Dall's sheep, Alaskan white sheep'
thinhorn sheep (Nichols tiZga, Bee and Hall 1956)
II. RANGEA. Worldwide
Dall streep occur in North America throughout.the .major mountain
ranges ot'ntaska, east through-the northern and southwestern moun-
taii..ng"t oi ttr. Yukon Teiritory, through the mountains of the
Northwesi Territories, and in the mountains of the northwest
corner of British Columbia (Nichols 1974).
B. StatewideDall sfreep are distributed throughout suitab'le alpine habitat'
g.n.ruity'above 2,500 ft, in maior mountain ranges of Alaska'
77
inc'luding the Brooks Range, the Alaska Range from the Canadian
border to Lake Clark, the Wrangell Mountains, Chugach Mountains,
Ta'l keetna Mountains, and portions of the Kenai Peninsula
Mountains. Small discontinuous populations exist in the
Tanana/Yukon uplands (Nichols 1978a, Heimer and Smith 1975).C. Regional Distribution Summary
To supplement the distribution information presented in the text'
a series of bluelined reference maps has been prepared for each
region. lrlost of the maps in this series are at 1:250,000 scale'
but some are at 1:1,000,000 scale. These maps are avai'lable for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition'
a set of colored 1:1,000,000-sca'le index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regiona'l guide.
Dall sheep are found in the Kenai Peninsula, Chugach, Wrangell,
and Ta'lkeetna mountains. Population densities and compositions
vary through the range. (For more detai'led narrative information'
see vo'lume 2 of the Alaska Habitat Management Guide for the
Southcentral Region. )
III. PHYSICAL HABITAT REQUIREMENTSA. Terrestrial
Sheep are capable of using all suitab'le habitat in the mountain
ranges they occupy. 0n a seasonal basis, there is generally'little difference in the physical habitat parameters that sheepprefer. Typica'lly, precipitous terrain with rocky slopes, ridges,
and cl i ffs are used; thi s habi tat preference i s most 1 i kely
re]ated to predator avoidance (Geist 1971, Murie 1944).1. llinter. In winter, sheep utilize sou_thern exposures where
avTTl-able, which provide areas of shal'low snow and maximum
solar radiation for warmth (Murie L944, Geist 1971). In some
locations, however, sheep utilize northerly exposures where
the wind exposes forage on ridges (Nichols, pers. comm.;
Murie 1944). They will sometimes move from exposed slopes to
protected cliff areas prior to storms (Heimer, pers. conrn.)
and occasionally gather together in c'liff crevices or caves
for warmth and to avoid strong winds (Geist 1971, Hoefs and
Cowan L979).2. Spring/lambing. The spring range of Da'l'l sheep is in general
simTTarFo-Their winter range, except that they move to lower
elevations and more southerly exposures (Heimer, pers.
corrn. ). Near Cooper Landing and at Indian, south of
Anchorage, for example, sheep are known to use the low
elevation, south-facing s'lopes in the spring (Nichols, pers.
conm.). South-facing c'liffs and slopes are apparently very
important in spring, affording maximum solar radiat'ion for
warmth and faster snow-me'lt (Geist 1971, Nichols 1978b).
Preferred lambing areas are on the most precipitous, inacces-
sible cliffs available (P'itzman 1970, Hoefs and Cowan 1979).
78
3. Summer. Dall sheep habitat requirements during surnmer are
eisenTial'ly the same as at other periods, although they may
tend to uti'lize shady areas and rjdge tops more frequently to
obtain re]ief from insect harassment (Murie 1944).
IV. NUTRITIONAL REQUIREMENTSA. Food Species Used
Heimer' (1983), in h'is study of different qua'lity sheep populations
in the Alaska-Range, deteimined that selectjon of forage species
by sheep is sea!onal and location-speci.fic, _ indicating that
ciution ihou'ld be used when extrapolating sheep food species from
area to area. He concluded that sheep select different forage
pt ants on di fferent ranges , partl_y on the basi s of thei r
ivailability. Therefore, {roups'of plants, rather than jndividual
p'lant species, offer a more tenable means of categorizing the
iorage uised by sheep. Heimer (1983) c'lassif ied these plant groups.
as f'ollows: -grass'and sedge/leaves and stems;. wggdy stems anq
associated qieen leaves;'leaves of willow (!atix spp.) a!d
mountain-aveis (Dryas spp.); forb basal parts lmajnly Oxytropis
spp. in the Alas[E-ilange); and lichens and mosses.
1. Winter, Preferred foods:
a. Riait<a Ranqe. In the Alaska Range, Dall sheep prefer
ffie-Tffid seed heads of grasses available above the
snow (Calamagrostis. sPP., Fes.tuca. s.PP.' lglopyron SPP.'
poa spFffi-lCarex hep6utnli.) ,. and 'lowbush cran-
Serry' lt6irs (Vicci ni-unr vi tEiliaeal (Mupi e L944, Heimer
1e83 ) .
Murie (1944) found that the winter diet of sheep in
McKinley Park averaged 81.5% grasses and sedges.
b. Kenai l'l-'ountains. ttictrots (.|97a) found that relatively
6-pTanT specTes comprise the majority of the winter
sheei diet bn the Ken'ai Peninsula. Grasses- (primarily
Festirca altaica and F. rglfq) and sedges (Carex spp.)
wffiost ffion'ly use-d,TiTh- occas'ional use of shrubs
(crowberry f Empetium nigryml, wil'low IS9],ix spp.l). and
forbs ( Et'i geron sPP. , Dryas sPP. ' ta I se ne I I eDore
[Veratrum VTFTilel).
. .
_c. Ym'n TerrTEo'rx Hoefs and Cowan (1979) found that sage
l7ilffiT sTa spp" ) wqs an important wi nter food, a'long
wTThlasses and sedges.2. Sprilg/lambin,q, Preferr,ed -f-ogd.s-. As mentioned, s.leeq- pe!-
erat ty move ro lower e'levations in early spring (April ) -!otake - advantage of vegetation exposed by the snow-mel t.
0verwintered -snow-cured grasses and sedges and I ignified
cranberry stems and associated leaves and berries are
importani forage items at this time (Heimer 1983).. As.
veletation begi-ns to grow again, grasses (Festuca.:Pp.) unq
sedges are initially sought, and mountain-avens, will_ow' and
Vaciinium spp. are utilizid as soon as they 'leaf-out (Whitten
1975).
79
3.Summer, preferred foods:a. Alaska Range. |r{hitten (1975) observed that sheep during
sumler feEd primari ly on the most pal atable and
nutritious plant parts, the leaves, buds, flowers, and
herbaceous stems.
Winters (1980) found that relatively few plant species
formed the major portion of the surmer diet. The most
b.
comnonly used food species during sunmer in the Alaska
Range i nc'l uded Dryas octopetala; several grasses 'notibl.y Festuca a-]taica andTierochloe alpina; sedge
(Carex- ffihffiT- wi]Jds-TSaITx polaris(Carex- ffihffialr wi]lds-TSalTx pplsru
pseudopolaFTilanZE reticulata ) ; and To'F55, EpTToETilfr'
Tl:fiTo'fiurn. 0xvria ?iqvnallfti-Oeum rossi i ).-14-RenaT-TountaTns. TicFol s ( 1974I found on the Kenai
B.
FenifisTla fi;f sedges were occasional ly more abundant
and made up a larger portion of the sumner diet than
other conunonly utilized grasses (Hierochloe alpina and
Festuca spp. ) and wi I lows.
Types of FeedTig-Areas Used
Sheep use areas where forage quality and quantity is the best
available during that time period. Areas of use change throughout
the year in order to meet these requirements.1. Winter. In early winter, sheep use lower-elevation slopes
lTilFie 1944). These slopes provide forage of good quality
and quantity, even though they are snow-covered (l'lhitten
1e7s ) .
As winter progresses and snow becomes deeper and/or more
crusted by the wind, sheep move to exposed wind-blown' snow-
free ridges (Murie t944, Geist 1971, Whitten 1975, Nichols
1978a ) .
Hoefs and Cowan (1979), observing Dall sheep in the Yukon
Territory, found that 49% of all winter feeding occurred in
areas of no snow, 2I% in areas with snow less than 5 cm
(1.9 inches), and 17% in areas with snow up to 10 cm
(3.9 inches). About 9% of a'll feeding occurred in areas with
snow up to 15 cm (5.9 inches), 2.4% in snow depths up to
20 cm (7.9 inches), and less than I% in areas where snow
depths were between 20 and 30 cm (7.9 to 11.8 inches).2. Spring. Sheep move to 'lower-elevation, snow-free southern
sfopes, and even into shrub tundra areas at the base of
mountains to utilize early plant growth (Whitten 1975, Murie
1944). The winter-cured vegetation may have nutritional
values comparable to late-summer vegetation (l{hitten 1975;
Heimer, pers . cornn. ) .3. Summer. Virtual'ly a1l sheep range is available at this time;
tr'6ilffir, a general trend is for the sheep to move gradually
up-slope, following the new plant growth, which is highly
nutritious, mainly using southern slopes but also other
aspects. In late summer, feeding is extended to northern
slopes, where green plant growth occurs'later (Wtritten 1975).
80
c.Factors Limiting Availability of Food
1. Winter. Hlimer (pers.- comm. ), during his observations of
DiTI-sneep in th; Alaska Range, found that snow over 18
j nches de'ep forced sheep to jor_age _on wi nd-swept hi gher
riAga; for'less readily available, less nutritious food
species.r'riir,oii ( tsz+1 , i r hi s study on the Kenai Peni nsul a ,
determined that snow hardness appeared to be more important
than snow depth ; however, both factors combi ne to I imi t
di ggi ng acti vi ty 'Uy shee-p. Most {i g-gl ng for fgra.gg - occurred
in"ireis where inow was iess than 1 fl deep. Wind-blown snow
deve'lops a trust that is difficult for sheep _to-.paw through
(e.ist'and Petocz 1977, Nichols and Erickson 1969)'
ihaw-freeze conditions during winter can develop an ice layer
sometjmes severa'l i nches thick, which sheep cannot paw
ifriougl' (Geist 1971). Unusua'l1y warm. winters with heavy wet
snow ind/or rain can cause these icing conditions (Nichols
igiSa), ut happened in late winter 1969-1970 in the Kenai
Nornliins (Nicho1s, pers. comm.) and in December 198f in the
Alaska Range (Heimer' pers. comm.).
?. Sprinq. Wiritten (tgZ5) speculated that sheep utilize areas
ffiirty green-p'lant growth to maximize their nutrient
uptake.
Feeding Behavior
Sheep ire selective in their foraging.pattern., concentrating on
what is most palatab'le, nutritious,, ahd available to them in the
ir.i (e.iti 1gzr, wnittln 1975). (3ee IV.A. Food Speci-es Used. )
1. hlint... Pawing or cratering in snow by s-heep.allows access
to-:FoFage planls underneath. Sheep will f_eed in one crater'
en]arge-it, gaining access to all forage p_'lants, then move to
anoth6r site- and Create another cratei (Geist 1971, Nichols
and Heimer Lg72). Smaller or less dominant animals are
sometimes forced to move from feeding craters by older or
larger sheep (tt'ichots and Heimer 1972).
feeding cralers on the Kenai. were dug .in.snow 9P t0.10. inches
oeep ("ibjd.). Murie (1944) reported that sheep had pawed
through snow uP to 14 inches deeP-
sheep"show a pattern of limited energy expend'iture during
wintbr, with ldss feeding activity in the morning and more in
the warmer afternoon periods (Geist I971, Hoefs and Cowan
1e7e).2. Sprinq/summer. whitten (1975) found that during spring and
+ffi-efTh.eep selected high-qua1 ity, ngw-growth vegetation and
chose the mbst nutritious species within mixed stands.
Mineral Licks
He'imei (!SZS1, in his study of Dall sheep mineral lick use in the
Alaska 'Rang6, recorrnendei that mineril I icks be considered
Critical traiitat areas for Dal I sheep populat'ions in interior
Alaska. This recommendation resulted from a study showing that
al'l segments of the study population utilized the licks with a
D.
E.
81
high degree of fidel ity, that there was preferential use by
lactating ewes, and that sheep travel significant distances (tZ +
mi), sometimes out of their way, to visit'licks (Heimer 1973).
Mineral 'licks provide physiologically important ions for sheep,
including calcium, magnesium, sodium, and potassium (ibid.).
The extent and dependency of lick use has not been documented forall Dall sheep populations in Alaska. It is not known, therefore,
whether the above findings are true for all sheep populations.
Until further studies are conducted to doZ-ument additional 'lick
sites and the degree of uti'lization by different populations, the
importance of all mineral lick areas should be recognized by
managers.1. Interior: Alaska Ranqe-Dry Creek. Seasonal use of this licko:crr-rllrrom@ July, with the peak of use
varying but usually occurring from the first to the third
week of June (jbid.). Ewe fidelity, or annual return to thelick, was 100%; ram fidelity was 80% (ibid.). Rams begin usein mid May-ear1y June, followed by juveniles, and then ewes
and lambs in late June-ear1y July (ibid.). Rams and ewes
without lambs spent an average of four days at the'lick.
Ewes with lambs spent an average of six and one-half to seven
days ( ibid. ).2. Southcentral: Watana Hills-Jay Creek. Seasonal use of this
TiTk-occurs fro@ least mid August, with
peak use occurring from mjd May through June (Tankersley
1984). Rams begin lick use in early May, followed by
ewe-yearling groups in late May and ewes and lambs in mid
June (ibid.). nt least 3L% (a minimum of 46 of 149 sheep) of
the observed 1983 area sheep population visited this lick
(ibid. ).
Another mineral lick located near the east fork of Watana
Creek was also utilized seasonally by Watana Hills sheep. A
minimum of 47 different sheep utilized the east. fork lock'
which is at least 37% of the observed population (ibid.).
The exact number of different sheep visiting both licks is
undetermined. However, it appears that most of the
populat'ion is using one or both of these licks.3. Arcti c: Brooks Ranqe-Hul ahul a Ri ver. Seasonal I i ck use
occrlrs fro perhaps a'11 year, with
peak use occurring in June (Spjndler 1983). Rams utilized
the lick primarily before ?6 June, with ewes, lambs, and
yearlings increasing after that (ibid.).
V.REPRODUCTIVE CHARACTERISTI CSA. Reproductive Habitat
Breeding occurs on the
broken, steep slopes.
normal breeding areas,
1e71 ) .
winter range in high cliff terrain or on
0ccasional breeding takes p'lace away from
usually following a ram-ewe chase (geist
82
Lambing occurs on portions of the winter rangg:.in areas of steep
broken- precipitor.is terrain (Nichols 1978b). Areas where
protection from wind and other weather factors is available are
iavored (Pitzman 1970).
Breeding Seasonal ity
The peit< of breeding activity extends ap.proximately from mid
November through mid December (Nichols 1978b).
ifre fimbing peiioa extends from late May through mid June (Nichols
1978b). The'estimated peak date of lambing on the Kenai Peninsula
was 24 May (ibid.).
Breeding Behavior
Breedin! is polygamous and. is conducted mostly by dominant rams
(Geist iglt,'Niiliols 1978b). Dom'inance among.rams is determjned
in September and Qctober by. a complicated_ display ritua'l .and
occasional combat (Geist 1971). The physical effort expended by
dominant rams during breeding depletes their energy reserves'
leaving them in pooi physical condition. A severe wjnter may
result-in the deadh of these individuals (ibid.).
D. Age at Sexual MaturitY
Rims are sexually mature at 18 to 30 months; however, dominance
order usually prdvents breeding until rams are six to eight years
old (t'1ichots- 1978b). Ewes are sexually mature at 18 to 30 months
are usual, although twinninj has been reported
The gestati on period i s approximate'ly 171 days
F. Frequency of Breeding
fwed can produce one- lamb a year (ibid.). Under some conditions'
ewes produce only one lamb every other year (Heimer 1983).
VI. FACTORS INFLUENCING POPULATIONSA. Natural
Deep snow and severe icing conditions appear to be-.maior factors
in 'l imiting sheep popu'lations in maritime areas (Nicho'ls 1978a'
Murie 1944).
Wolves may'be a major predator in areas where the wolf.population
is high and/or esclpe terra'in is limited (Murie 1944, Heimer and
stephenson 1982). Predation by bears, goygtgs.,. lynl, and other
predators occurs but appears to be minimal (ibid.). Golden eagles
ire thought to be serjous predators of lambs during their first
few weeki of life (Heimer, pers. comm.; Hoefs and Cowan 1979).
Major diseases and parasites associated with Dall sheep in.Alaska
inllude contagious ecthyma, lungworm-pneumonia comp'lex, mandibular
osteomylitis ('lumpy jaw), and several species of gastro-intestinal
helminth worms (Neiland 1972).B. Human-related
The most serious human-related threat to Dall sheep in Alaska
comes in the form of introduced diseases from domestic sheep.
tllild animal populations seldom have the defenses necessary to
B.
c.
E.
(ibid.).
Fecundi ty
Single bi rths
rarely ( ibid. ).(ibid.).
83
withstand introduced disease. Introduced diseases were
responsible for most of the decimation of.wild sheep populations
in'the western United States (Heimer 1983). 0ther human-related
factors influencing sheep populations are the following:
" Competition with introduced (wild or domestic) animalso Harrassment, activeo Harrassment, passive: construction noise, aircraft traffico Vegetation damage/destruction due to grazing by domestic
animal s
(See the Impacts of Land and Water Use volume of this series for
additional information regarding impacts. )
VI I. LEGAL STATUSDall sheep i n A'laska are managed as a game anima'l by the Al aska
Department of Fish and Game.
VIII. LIMITATIONS OF INFORMATION
Informatjon is needed on the relationships of breeding success of rams
vs. hunting mortality of older age classes.
Information is also-needed on factors influencing winter survival of
younger age c'lasses, and whether mineral licks are necessary for sheep
survival.
Crit'ical habitat components for sheep populations should be delineated(e.g., tninera'l licks), and further research on mineral lick
relitionsh'ips should be conducted. Basic research on the population
dynamics of Dall sheep is needed.
Description and delineation of breeding and lambing habitats, as wel'l
as of winter ranges, is needed.
REFERENCES
Bee, J.t,l., and E.R. Hall. 1956. Mamma'ls of northern Alaska. l4useum of
Natural History, Univ. Kansas, Lawrence, Kansas. Misc. Publ. No. 8.
Geist, V. I97I. Mountain sheep: a study in behavior and evo'lution. Chicago
and London: Univ. Chicago Press. 371 pp.
Geist, V., and R.G. Petocz . 1977. Bighorn sheep in winter: do rams
maximize reproductive fitness by spatial and habitat segregation from
ewes. Can. J. Zool. 55(1):1,802-1,810.
Heimer, W.E, L973. Da'll sheep movements and minera'l lick use. ADF&G,
Fed. Aid in tl|ildl. Rest., final rept. Projs. W-I7-2 through 5,
Job 6.lR.
rept.
1983. Interior sheep studies. Fed. Aid in l,.lild'|. Rest, final
Projs. W-17-8, 9, 11, and W-ZL-I and 2' Job 6.12R.
. 1984. Personal corrnunication. Game Bio]ogist, ADF&G, Div. Game,
TTrbanks.
B4
Nichols, L. 1974. SheeP rePort.
prog. rePt. Vol 15. Proj.
i,roj . t,.|- 17-6, Jobs 6.3R, 6.4R '
. 1978a. Dal I 's sheeP.
Heimer, W.E., and A.C. Smjth. Lg75. Dall ram horn growth and population
quality ana- ineir i'ignlficJn.. to Dall sheep management in Alaska'
Tech. Bull. 4. 41 PP.
Heimer, w. E. , and R.0. stephenson. 1982. Responses of^ Dal I sheep
populations
-to wolf control
-in interior Alaska. Pages 320-329 E.l.A'
bili.V, €d.
-RroJeeOlngs of the third biennial sympos-ium on northern
,ifa if,..p and 9;;a coincil, March 17-19, !982, Ft. Collins, C0.
Hoefs, M., and I.M. Cowan. Ig7g. Ecological.investigation of population of"-- -Oal1'sheep. Synesis, bol . 23, supplement 1' 81 pp'
Murie, A. 1944. The wolves of Mt. McKinley. NPS Fauna Ser' No' 5' USDI'
238 pp.
Nejland, K.A. Lg72. Sheep disease studies. ADF&G, Fed' Aid' jn tl|jldl'
Reit., pro3. prog. repi. Vol. 1. Proi' t'l-17-3, Job 6'6'R'
ADF&G, Fed. Aid in t,lildl. Rest.' proi'.
t.l-17-5, Jobs 6.3R,6.6R and 6.7R; and
--D.T. Gi I bert, eds. Bi g game
Stackpo'le Books.
6.5R and 6.7R.
Pages 173-189 i n J. L. Schmidt and
of North AmeriG-. Harri sburg, PA:
. 1978b. Dall sheep reproduction. J. Wildl. Manage. 42(3):570-580
Nichols. 1., and w. Heimer . tg72. sheep re-por.t. ADF&G, Fed. Ald jn hlildl '
Rest.,Proj.prog.rept.vol.13.Proj.t,l.17-3,.lous6.lRthrough
O.Sn;
-anO iroi'. W--fZ-+, .loUs 6.1R through 6'5R and 6'7R'
pitzman, M.S. 1970. Birth behavior and lamb survival in mountain sheep in
Aliska. M.S. Thesjs, Univ. Alaska, Fairbanks' 116 pp'
Spindler, M.A. 1983. Dall sheep.mineral .lic.k use and age and sex composi-
tion in s.ieii.A river dri'inages, Arctic Natjonal Wildlife Refuge'
tgTg-lg1z. Anwn F'inal Rept. FY83. USFWS, Fairbanks, AK. 52 pp.
Tankers'ley, N.G. 1984. Susitna Hydroeleglljc Proiect final report: big
game itudies. Vol. B: Dall sheep. ADF&G' Anchorage'
whitten, K.R. 1975. Habitat relationlhr'ps_ and. popula-tion dynamics of Dal I"' '--ir'..0 (oui;-a;iti aitil) in Mt. McKinley Nitional Park, Alaska. M.s.
Thesi s ,-TnTvlTask;Fi rbanks . L77 pp.
W.inters, J.F. 1980. Summer habitat and food utilization by.Da11's-sheep
and thei...-tutions io body and horn size. M.S. Thesis, Univ. Alaska'
Fairbanks. 129 PP.
85
Moose Hfe History and Habitat Requirements
Soutlrrest and Southcentral Alasha
\
I.
II.
NAME
A.
B.
RANGEA. Worldwide
The Alaskan moose
of Alaska, western
( Franzmann 1978).
ffi ft .#f#.J,' :nf ' ;illi:ff
"li[?:fl
'3:1,ilffi :
B. Statewide
Moose are distributed throughout Alaska except for -portions of the
southeast.rn- p.ntinat., th6 southwestern Aiaska Peninsula' most
offshore isianai, ind giaciated areas. In Southeast Alaska' moose
are found on-lf,.'t'tit as[i nu iJi.f inds , Yakutat fore'l ands , the ri ver
..4
Map 1. Range of moose (ADF&G 1973)
Corrnon Name: Moose, A'laskan moose
Scientific Name: AlceS alces gj gas (Peterson 1955)
87
va1leys between Haines and the Canadian border, Berners Bay and
Taku River, the Stikine River valley, and other drainages abutting
Canadian herds (ADF&G 1976a, 1976b, 1976c). Moose are generally
found at or below 4,000 ft e'levations (Ballard and Taylor 1980,
Bal I ard et al . 1984).C. Regional Distribution SurmarY
To-supplement the distribution information presented in the text,
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 12250,000 _scale'bui some are at 1:1,000,000 sca'le. These maps are avai'lable for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition,
a set of colored 1:1,000,000-scale index maps of selected fish and
wild'life specjes has been prepared and may be found in the Atlas
that accompanies each regional guide.
1. luthwest. Moose are present throughou^t th_e^^Southwest Region
maTnTaE generally below elevations of 4,000 ft. Few moose
exi st south of polt Mo] 'ler on the Al aska Peni nsul a (ADF&G
1976a, Bal'lard and Tayl or 1980, Bal I ard et a'l . 1984) . (For
more detailed narrative information, see volume 1 of the
Alaska Habitat Management Guide for the Southwest Region.)
2. Southcentral. Moose are distributed throughout much of the
ffilFceiltraT Regi on mai n'land, general ly be'low el evati ons of
4,000 ft (ADF&G 1976b, Ballard and Taylor 1980, Ballard et
al. 1984), except in glaciated areas such as occur in the
Wrangell Mountains. They are also absent from western Prince
1.li'lliam Sound from Valdez to Kings Bay. Moose are also found
on Kalgin Is'land in Cook Inlet, as a result of transplants in
1957, 1958, and 1959 (Burris and McKnight 1973). (For more
detailed narrative information, see vo]ume 2 of the Alaska
Habitat Management Guide for the Southcentral Region.)
III. PHYSICAL HABITAT REQUIREMENTSA. Aquatic
Moose feed on aquatic vegetation during spring and surmer. Th-ey
may also seek rel'ief from insects in- deep water (F1ook 1959).
(For further discussion, see Terrestrial Cover Requirements,
below, and IV. NUTRITI0NAL REQUIREMENTS, A. Food Species Used. )B. Terrestrial Cover Requirements1. l,linter. h|il'low (Salix spp.) shrub communities, in alpine
ariilFlparian environments are very important habitats for
moose during winter, supplying most of its winter food (see
IV. NUTRITIoNAL REQUIREMENTS, A. h,inter). Coniferous tree
stands may also provide seeded food and also serve as cover,
especially for cows with calves, which seek denser cover than
do other moose, presumably for greater protection from
predators (Peterson'I977) and lower inow depths (Coady 1982).
2. Spring. Moose typically begin feeding upon grasses, sedges,.
aqTEfrc and semi-aquatic vegetation as soon as snow- and
ice-melt permit. In many areas, cows usual 1y select
88
well-drained, dense islands of trees and shrubs as secluded
Ui.tt sites, which probably Serve as protective cover for
their calvei (Peterdon 1955, Rausch 1967). These calving
ui.us may be characterized by dense clumps of spruce (llSgu
spp.) inierspersed with alder (Alnus spp.), or willow (Salix
;ffi.i,'u.tv-iike'ly serve as protftTr-le'iover from the naffidT
eibmilnts inOfAe 1973), as well as from.predators or other
disturbances. Modafferi (tgeZ and 1983) described ca'lving
areas for radio-collared moose from a subpopulation a'long the
Susitna River north of Ta'lkeetna that were gross'ly different
from those descrjbed above. He found that spruce waS the
least common and abundant of four major tree types present
that were used by this subpopulation. Use of muske.g meadows
was not observei. Cottonwoild (Popul us tri cosa.f pa ) was thq
most commonly occurring vegetative type 1n cqlving areas ano
dominated i; canopy coverage. It is 1ike1y that calving
areas vary greatiy throughout the state and are often
wi despread.
Summei^. Genera'1ly, moose feed in open areas_ and use the
So ing shiubs
- ind forest for cover (LeResche 1966) '
Calves, -however, tend to avoid exposed areaS in which cows
browse and graze (Stringham I974).
Moose only occasional 1y bed down i n open wet meadows 'preferring the drier ground among hummocks _n.eal the _edges of
wittow, siruce, and mixed forest stands (LeResche 1966).
Fall. Generally, moose tend to occupy .higher open areas
Ifing the rut. Ballard and Taylor (1980) .found that moose
occupied willow habitats more duling September, 0ctober, and
Deceinber than the remainder of the year in the upper Susitna
va11ey. Most moose collared during the winter along !tqloweisusitna River flood plain did not spend the rut period
in or near their winter ranges. Most rutted to the west of
the floodplain, with some individuals as far as 40 km away
from the 3usitna River (Modafferi 1984). Generally, rutting
concentrations of moose occur at or above timberline' but
they occur at lower elevations also. Ea.r'ly snows qay force
mooie to move to wi nteri ng areas , and , converse'ly, warm
weather may enable them to linger in summering areas.
IV. NUTRITIONAL REQUIREMENTSA. Food Species Used1. Winter. Deciduous shrubs and trees protruding through
acffi-utated snow on the ground and within reach of moose are
the primary food in winter. In some areas, however, moose
cratir in-snow to obtain nonbrowse forage, such as ferns
(LeResche and Davis 1973, Modafferi 1984). Several wi'l'low
species are prefemed, but thg order of preference varies
from area to area (scott et al. 1958, Peek 1974).. 0n the
Kenai Peninsula, 'littletree willow (S. arbusculo.ides) is most
pi.i.tt.a, tot l owed by scoul er wi t i o"
.l@1g)
' and
3.
4.
89
B.
bebb wi'llow (S. bebbiana) (Machida 1979). Barclay wil'low was(S. barclayi I-, Ieaffi'referred. In Interior, A'laska, the
oFder--oilpreference is feltleaf wil low (!. alaxensis),
diamondleaf wi'llow (S. planifolia ssp. pulchraT, wITET6TTeT
wil'low and halbreil wTTTow-E hastaEl preferred least
( i bi d. ) . After wi'l 'low, the molt preffiea browse i s paper
birch (Betula papyrifera) {LeResche and Davis 1973).
Because-ifrhe-q[nn-tffi-of forage it produces, quaking aspen
(Populus tremuloides) is also considered important in certain
aTeE-iT'rffiTqlFt-);
Foliose lichens (Pe]tigera spp.) may serve as an important
alternate winter:fqoA-source (LeResche et al. I974). In
areas of low snow cover and on depleted winter ranges,
lowbush cranberry and fol iose I ichens gan support high
dens i ti es of moos-e (LeResche and Davi s 1973 ) .
2. Spring. l,{illows are the most important food in spring.
nbJsefails (Equisetum spp.), sedges (Carex spp.), and aquatic
p'lants are TTfo important (nausctr ffi) . 0n the Kenai
Peninsula in late April and during May, foliose lichens and
fruiticose lichens (Cladonia spp.) made up more than half the
diet of tame mooseliTh-l owbush cranberry maki ng up the
remainder of the diet (LeResche and Davis 1973).
3. Surmer. Variety in the diet is greatest during surmer.
Iurin'g tfrls period, emergent vegetation and other herbaceous
plants may be grazed, but leaves and,succulent leaders on
shrubs and trees are also used (Coady 1982). Newly emergent
aquatic and marsh p'lants, inc'luding sedges, horsetails, and
pondweed (Potomogeton spp.), which are found in wetlands,
lakes, and-ponEs--Tn water up to 8 ft deep are consumed
(LeResche and Davis 1973, LeResche 1966).
During ear'ly growth stages forbs, such as fireweed (Epilobium
spp.) and lupjne (Lupinus spp.), are heavily used. Mushrooms
are eaten jn sunfriffin encountered (LeResche and Davis
1e73).In'late summer, emergent plants are used 1ess, and the diet
includes more browse (Bishop, pers. comm.).4. Fall. During fall, the transition from summer forage to
wi nt-er forage occurs . The use of browse i ncreases aS fal I
progresses because many herbaceous plants become unpalatable.
Types of Feeding Areas1: l^li nter. Shrub cornmuni ti es , such as a1 pi ne and I owl and wi'l I ow
FmilT, are the most important wi nter habi tat for food
(LeResche et al. 7974, Peek 1974). When snow depths are
minimal, moose general'ly prefer more open shrub-dominated
areas and sedge meadows (Coady L982). As snow depths
increase, moose shift to coniferous and deciduous forests
with closed canopies, when available, where snow accumulation
is less (Coady L976, Gasaway 1977) and understory vegetation
more available (LeResche and Davis 1973).
90
Mature, undi sturbed p1 ant communi ties, occurri ng both in
up1 and areas near timberl i ne and i n I owl and areas , are
iinportant late winter habitat, as are areas recovering from
man-caused or natural disturbances. Moose may remain on
their surnrer range if not forced out by deep snow (Ballard
and Taylor 1980). During late winter, some moose may remain
at higher elevations, where wind actjon or temperature
inversions reduces snow depth. Moose may crater through snow
up to 40 cm deep (Coady L982, Modafferi 1984).
Genera'|ly, upland areas of winter habitat are domjnated by
willow or-shrub birch (Betula qlandulosa) and lowland areas
by stands of spruce interspersed wi:[F-aEciduous tree stands
and wetland areas (iUiO.).
Z. Spring. Expanses of wetlands interspersed with dense stands
i?Trees aria shrubs, which are typ'ica]1y used for calving,
provide abundant early spring forage (iUit.). Moose use
hatural mineral licks in some areas of interior Alaska mostly
in spring and early summer to obtain sodium (Tankersley and
Gasaway tggs). Mineral licks used by moose occur in some
areas of Southcentral Alaska also; however, there are n0
detailed reports on these areas (Tankersley, pers. corrn.).
No licks are known in southwestern Alaska.
studies in Michigan and canada jndicate that aquatic
vegetation eaten by moose in the summer is an alternate and
sometimes better source of sodium and other .mineral elements
(gotkin et al. 1973, Fraser et al. 1982). Moose ljck use
declined when aquatic feeding increased in interior Alaska
(Tankersley and GasawaY 1983).
3. Sunrmer. Timberline shrub thickets (LeResche et al. 1974) and
lilland areas with ponds containing preferred aquatic species
(LeResche 1966) comprise primary feeding locations during.the
surmer. (See comment on salt licks under B. 2. Feeding
I ocati ons . )In mid-to-late summer, moose tend to move to up]and areas
away from bog areas w'ith standing water and to use browse in
dri6r areas (Aisnop, pers. comm.i 0iOrickson and Tay'lor 1978;
Ballard et al. 1984).4. Fall. Both lowland and upland shrub communjties may be
Teavi ly used duri ng fal I (coady 1982). ._ _In Southcentral
Alaska, moose typica]1y use up]and.areas (Ballard and Taylor
1980, Didrickson and Cornelius 1977).
C. Factors Limiting Availability of Food
Coady (1974) considered snow depth the most .importan-t limiting
factbr for moose. Migration from summer to and from winter [ange
and daily winter activity may be influenced by initiation of first
snow, snow depth, day length, and persistence of. Snow dgptt-ts
greater than 40 to 70 cm are generally considered the.uppel limit
ior areas utilized by moose (Coady L974). Snow depths of 90 to
100 cm are considered critical 1y I imiting (Nasimovitch 1955,
91
Ke'l sal I 1969, Tel fer 1970, Ke'l sal I and Prescott 1971) , because at
these depths movement is restricted and adequate food intake may
be impossible. Deep snow may also cover low-growing browse
species, reducing their availability and requiring moose to exert
greater effort to feed (Coady I974). In Southcentral AIaska,
moose general'ly confine their winter movements to areas less than
3,600 ft in Llevation (Ba1lard et al. 1984). The next most
important property of snow is hardness, which determines the force
necessary for moose to move through the snow and their ability to
crater for food.
The density, height, and distribution of forage plants determine
how much a- part'idular area and vegetation type is utilized (Milke
1e6e).D. Feeding Behavior
Peek feeding activity occurs at dawn and dusk. During fall, more
feeding activity occurs throughout the day. Fall feeding activity
i s usrial 'ly j nil uenced by fhe rut, ref 'lecti ng greater socia'l
contact (liest et al. 1976). Schwartz et al. (1981) found that
bull moose at the Kenai Moose Research Center quit eating entirely
during the rut and that food intake decreased in females. Geist
(1963) found that 79% of surmer activity involved feeding.
Cratering in snow to reach plants is common. throughout Alaska
during fi]l and winter (LeResche and Davis 1973).
V. REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat1. Breeding areas. There is little descript'ive dgta regarding
moose-FfittTng habitat. Use of habitat during the rut may be
be influenced by whether particular groups of moose are
migratory or nonmjgratorY.
Use of upland brush-willow habitat types reaches a peek
during the breeding period, corresponding with elevational
movements of moose (Didrickson and Cornelius L977, Ballard
and Taylor 1980, Ballard et al . L982' 1984).
2. Parturltion areas. Most studies conducted in the
ffi have found calving to be wide'ly dispersed
( Oi Ori ckson and Cornel i us 1977 , Bal I ard et al . 1982,
Modafferi 1982) (See III. 8.2., Spring.)
B. Reproductive Seasonal itY1.' Breeding. Breeding occurs. during _fa11,_ with. the peak of
ruTing-activity occurring between late September and earlV
0ctobei (Lent I974). The timing of the rut is remarkab'ly
synchronous among moose in different areas and years in North
America (ibid. ); this synchronism is reflected in the
consistency in calving dates observed throughout the range of
moose (Coady 1982).2. Parturition. Parturition generally_occurs .between late- May
affi ea-rfi-June. As a consequence of conception during later
estrus periods, some calving may occur later, which is
9?
disadvantageous to calves because their reduced size in fall
ruy-i.ii.n"their ability to survive the winter (Coady 1982).
C. Reproductive Behavior
Moose olten- form large aggregations during t-he rut-(Best et al.
i9t8i.- ih.r. ruttind grdips range in sizb from male and female
pairi to 30 or more aauits'(Coady-1982). There may be movement of
both bulls and cows to and from groups (ibjd')'
D. Age at Sexual MaturitY
Moose t;;A annual ly. Females may breed as _yearl ings (1-6 to
18 monthsJ ana are cipable of reproduc'ing annual.1y_until at least
year fg-tHouston 1968). B.ulls'are also phys'ica11y capable of
-breedi ng as Yearl i ngs ( i bi d. ) .
E. Pregnancy Rate/Number of Young- Born
Natility"raies for adult femaies range from 1.00 to t'20' -Eightyto 90% i,t uOutt females jn most moose populations'in North America
become pregnant annually (P'imlott 1959, Schladweiler.and Stevens
1973, simiin tg74). rfie birth rate fo1 tw-o-yea1--old females in
North America was found to be 0 to 0.47 (pimtott 1959, Schladwjler
and Stevent ig7i, Blood I974, Simkin 1974). In. the development.of
their rootl popufation model, Ballard et al. (1984) used Blood's
(1974) estimdrte of .?9 calves/two-year-o1d female'
ifre l'owest reported pregnancy and twi nning -rate.s- . f-or moose i n
North
"-n.r" -'AO%- (Fran"zmann 1981) and 2% (Pimlott 1959) 'respectiu.ty. The highest rates were 98% and 70%, respectively
iF.Snirunn it at. 1983, Modafferi _1984). Moose populations tend
to be on the higher end of this scale.
F. Gestation Period
The geslation period is approximately 240 to 246 days (Peterson
1e55 )G. Lactation Period
Cows lactate until fal1, then gradually wean their calves
( Franzmann 1978) .
VI. FACTORS INFLUENCING POPULATIONS
A. Natural1. Severe !L4!g_ll. Wi nter mortal i ty results ,
f rom factors
reTaFd-lffiT]y to snow depth, density, hardness, and the
persistence of ihese conditions over time (Franzmann and
Peterson 1978).
Winter severity often manifests itself first in terms of
reduced food ava'i I abi'l i ty and restri ction of movements and
later in terms of increaied calf and adult mortality because
of starvati on and i ncreased vu1 nerabi 1 i ty to predators
(p.irtott 1959, Peek 1974., Peterson and Allen 1974, Bishop and
Rausch !974, Sigman L977).
Recently conduited predator-prey relationship studies in
Aiaska iuggest that mbose morthlity because of_'wo1f predation
i s addi tive rather than compensatory. After a moose
popu'lation has declined from factors such as severe winters,
ovbiharvest, decl i ni ng range-carryi ng capaci ty, and/or
93
predation, 'limits on moose population growth because of wolf
predation can occur. In simple wolf-moose systems, predators
can maintain moose at low levels for decades (Gasaway et al.
1983, Ballard et al. in press).
Prior to the mid 1970's, both brown and black bears were
thought to be scavengers rather than predators of moose.
Studies of neonatal moose mortal ity indicate that both
species of bear can be successful ungulate predators
(Franzmann et al. 1980, Ballard et al. 1981). Bear predation
is the primary cause of mortality in some moose populations
and, similarly to wolf predation, is an additive source of
mortal ity. Experimental bear reduction programs have
demonstrated that calf moose surviva'l can be improved by
temporari'ly reducing bear numbers (Ba'l'lard et al . 1982).
Most moose populations produce adequate numbers of ca1ves to
enable population growth. When growth fails to occur, it
usual'ly is the result of high neonata'l mortality. The
relatjonship between habitat caryying capacity and ungulate
density is confounded by predation. Managers attempt'ing to
provide sustained yields of moose for human use wi'll find
predator management a necessity in systems containing
natural'ly regu'lated predator populations.
3. Disease and_parasj!1sm. Moose are subiec_t_ to a large number
@tes; however,.usually they are not an
important factors in population dynamics (Franzmann 1978;
Zarnke, pers. conrm. ) .4. Competition. Competition for food between moose and hares is
usu;Ily prevented by habitat segregation; moose, for examp'le,
prefer open seral communities, whereas hares inhabit dense
black spruce (Picea mariana) or wi'llow-al.der (S,alix-Alngs
spp.) thickets which provide more cover (LeResche et al.
!974, Wolfe I974). In general, direct competition is minimal
except for the remaining vegetation in areas where forage has
been extensive'ly depleted or deep-snow conditions force hares
to feed at highbr leve'ls on shrubs (l.lolfe 1974).B. Human-rel atedA summary of possible negative impacts from human-re'lated
acti vi ti es i ncl udes the fol 'l owi ng :o Collision with vehicleso Pol'lution of water and/or food supplyo Reduction of food suPplyo Vegetation composition change to less preferred or useable
s pec'r es
Vegetation damage/destruction due to grazing
animal s
Vegetation damage/destruction due to mechanical
materi al
Barriers to movement, physical and behavioral
Harvest, change in level
by domestic
removal of
o
94
" Harassment or mortality caused by domestic dogs, especial'ly
in deeP-snow conditionso Competion with introduced animalso Predation, increases
" Dit.ir. tiansmission from susceptibility to introduced and/or
domesticated animal so Harassment, active
(See ttre frpi.ti of Land and Water Use volume of this series for
idaitional information regarding'impacts')
VII. LEGAL STATUS
The Alaska bepartment of Fish and Game manages moose' .(S.tt the Human
Use section in volume 2 for a summary of moose management. )
VIII. SPECIAL CONSIDERATIONSA. Habitat Protection and Management
To sustain a moose populati-on, high quality habital .i.s essential.
Habitai proi".tlon'and managimeni may consist of the following
( Franzmann 1978):d S.iling asiO. large areas such as the Kenai National Refuge'
Alaska and the Matanuska Valley Moose Range. Limjting construction and other activities that restrict
moose m6vements between traditional seasonal home ranges and
within critical use areas of a seasonal home range
" fnfrjniing selected habitats to improve the carryin_g_ capacity
for moosi by prescribed burning, 1ogglng in small blocks,
'land cleariig,' and mechanical rehabilitation that returns
vegetation t6 early successional stages (0ldemeyer et al.
t977)
These !"u.t.i..t should be subject to total resource planning.and
be coh.'pitiUt. with other resource-management considerations
( Franzmann 1978).
X. LIMITATIONS OF INFORMATION
Data are sparse concerning annual and seasonal habitat use by moose,
and area ip.liti. infordation i s needed regarding. these seasonal
habitat requ'irements. Popu'lation identity and movement studies need to
be completed in order to identify migrational patterns-and habitats
important to the maintenance of specific subpopulations of moose.
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Moose mi grations in North America.Nat. Can.
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99
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Alaska. Can. J. Zool . 6I:2,242-2,249.
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Zarnke, R.L. Personal communication. 1985. Disease and Parasite
Specialist, ADF&G, Div. Game, Fairbanks.
100
Bald Eagle Life History and Habitat Requirements
Sbuttrrest and Southcentral Alasha
I.
Map 1. Range of Bald Eagle (ADF&G 1978)
NAMEA. Common Name: Bald Eag'le
B. Scientific Name: Hal iaeetus I eucocephal us al ascanus
II. RANGEA. Worldwide
Bald Eagles are known to occur from northwestern Alaska, through
the Alajkan interior, across interior Canada (MacKenzie, Manitgba'
southein 0ntario, southeastern Quebec, and Newfoundland),.south to
the A'leutian Is]inds, Baja California, Arizona, New Mexico' Gulf
Coast of southern Texas, Florida, and occasionally in northeastern
Siberia (Terres 1980, Gabrielson and Lincoln 1959).
101
B. Statewide
The largest concentrations of Bald Eagles are_found along_ ttte
coastal -areas of Southeast Alaska, the Gulf of Alaska, the Alaska
Peninsula, and the Aleutian Islands (excluding the Near Islands).
Although not in the densities present in the maritime regions'
Bald Eigles are also found along major river drainages of I'lestern,
Interioi, and Southcentral Alas[a (eaUrielson and Linco]n 1959).
C. Regional Distribution SummarY
To-supplement the distribution information presented in the text'
a seri'es of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 _scale'bul some are at 1:1,000,000 scale. These maps are availab'le for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition'
a set of co1ored 1:i,000,000-sca'le index maps of selected fish and
wi'ldlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.
ApproximatAly 45% of the breeding population occurs in Southeast
Aiiska, 25%-in Southcentra'l Alaska, 20% in the Aleutian Islands'
and 10* in the remainder of the state (Hodges 1982).
Bald Eagles normally winter along the southern coasts of A'laska,
with some movement of b'irds, especially inmature birds, into
British Columbia and the continental United States (ibid.).
Bald Eag'les breed cormon'ly about the shores of B'ristol Bay, around
Il iamna and Clark lakes, and less abundantly in suitable
local'ities on the coast of the Bering Sea, north to the Noatak
River (gaUrielson and Ljncoln 1959). (For more detailed narrative
information, see volume I of the Alaska Habitat Management Guide
for the Southwest Region and volume 2 of the guide for the
Southcentral Region. )
III. PHYSICAL HABITAT REQUIREMENTSA. Aquaticgver its entire range, the Bald Eagle is typically associated with
I and/water i nterfaCes - shorel i nes and ri veri ne areas. Thi s
association appears to be related to food sources, but other
factors may a'l's'o be important (Hughes' pers. comm.).
B. Terrestrial Cover Requirements
Bald Eag'les are also associated with prominence_s, which are used
for perChes and nests; typjcally, these are the larg.est trees near
land/water interfaces, although cliffs and sea stacks may also !eutilized, especially along the steep, rugged coastljne of the
Aleutjans (White et al. I971, Beebe L974). Where foliage is
available, Bald Eagles show a strong preference for nest sites
with overhead and surrounding foliage providing shelter from wind'
rain, and sun; large o1d-growth trees are strongly preferred sites
(U.S: Army Corps oi Enginiers 1979, USDI 1980).
During hai.sh wbatherin tfre Chilkat Valley in Southeastern Alaska'
eaglei abandon primary roost areas and seek shelter in conifers
ani cottonwoods'to reduce heat loss (hlaste 1982).
102
In Southwest Alaska, Bald Eagles' preferred habitat lies with'in
several hundred meters of' the coastline or along- rivers
inOflnlUSfWi ig8il. In Southcentral Alaska, eagles pre-fer nest
s.ites near clear streams, where jce breakup occurs in early spring
(Bangs et al. 1982).
IV. NUTRITIONAL REQUIREI'IENTS
A. Food SPecies Used
rnrougfiout- their habitat, Bald Eag'les are highly opportun'istic
feeders. They may scavenge valioui forms of carrion and/or prey
upon tiifr, sniall 'mammals,- 9r !'i1ds (Beebe L974). ll!h' however'
appear to be the preferreU tooO item of Bald Eag1.es (Wright 1953)'
In .ousllt areas, shorel'ines are often searched for stranded or
dead fish (Beebe I974). l{|inter-ki I led deer carcasses are
,.uu.ng.j" in'-iiie winter-spring -in Southcentral and Southeast
Alaska (Hughes, pers. -iot*i). " According to- Bee.be . (1974),- ilr
coastalareascrabs,octopi,andothertidepoolanimalsareoften
preY for Bald Eagles.
1. Southwest Region. In the Aleutians, Murie.-(19a0) fgu1d the
iffi;ld Eagles to be 81% bi.rds (lg-U of which were
t.iUi;i;I A.ST" fish," and 7% ryaTIa]s (none of which included
,;;-;ii;;il. sn.r.oi et al. (1976), however,. found that sea
otter pups n.r.-r.grlarly oepreaateo.uy nesting adult ggJa
raqies.' 'Gaurietson"inJ iln.oin (1959) repo.rted that in the
niEriiin. -.ugi., feed ma.i n1y on seab j rds (..g, ., murrel ets ,.
shearwaters,
-and fuimars). -t,Jhite et al. (1971) discovered
inii on Amititta riianA 'tne Bald Eagle's diet consisted of
26% blrds, 28% fish, and 46% mammals'
iniuna i; Southwest Al aska, food i s probab'ly a 1 imi ti ng
ii.lo., ur it is .in the interior for breeding Bald -Eag'les..Ouring'tite June on the Tatlawiksuk River, an adult Bald
Eaqle was seen.iting lungs from a moose carcass (Mindell and
Do[son 1982).Z. iouit'lenltij negion. 0n the Kenai N1n1R, salmon comprised a
mffiagles' . summer diet. Also, eagles.-were
iourO do utilize streims where spawn'ing rainbow trout (Salmq
ffi};$:f*'il##i*ffihffi
(Bangs et al . 1982).
B. TyPes of Feeding Areas Used
fibtes often congregate jn large-- numbers along salmon-spawning
streams to feed bn -spawned-out-fish, and in coa_stal areas' as
previ oustV noGi, shorel i nes are often searched for stranded or
aeaO iiifr" (geeUe'Ig7i).- 0ccasiona1ly, Ba'ld Eagles take I ive fish
from lakes and streams (Grubb 1977J and from the ocean surface
(Westlund, Pers. conm.).
103
V.
Lakes with potential food supplies bordered with strips.of. mature
timber and imall knolls for observational sites are probably very
attractive to foraging eagles (Bangs et al. 1982).
C. Factors Limiting Availability of Food
High prey visibi'lity is important for foraging success. _Fishing-suiceis is reduced iln 'lakes with turbid water, and the effect of
wind on water also lowers fish-capture rates (Grubb 1977).
D. Feeding Behavior
Bald Elgles frequently locate a fish from a conspicuous. perg!'
then sw6op down'and strike. They may also locate fish while
flying over the water, then swoop and strike. They also wade into
stri't t 6w water and catch f i sh wi th thei r beaks , characteri sti ca'l ly
submerging their heads or standing on ige and reaching into the
water with tatons or beaks (Southern 1963).
REPRODUCTIVE CHARACTERISTICSA. Reproductjve Habjtat
As previously mentioned, Bald Eagles typically nest in large
trees, a'lthough they may nest on rocky cl_iffs, pinnacles_ of rock'
and occas'ioni1'ly on the ground (Gabrie'lson and Li ncol n 1959).
Nests are usually situated within a few hundred meters of water in
sites that afford both security and isolation (Sherrod et a'l.
1976). The nest is usually a large structure of sticks lined with
seaweed, vines, grasS, plant sta]ks, and sod. The center of the
nest is lined wiitr teaves, mosses, straw, and feathers, usually to
a depth of four inches (Gabrielson and Lincoln 1959). Kalmbach et
al.'(1964) computed nests in Alaska to average about l.l t high
and 2.1. m jn diameter. They are genera'l1y used by a mated pair in
successive years and added to each year. Ba'ld Eag'les normal ly
will not begin a nest where human disturbance is evident (Catt
1e78).
Throughout the range of the Bald Eagle the genera'l attributes of
nestiig trees are- similar, although the preferred specieS of
nestin! tree varies with locatjon (Lehman 1978).
Nest trees are usually close to water, have a c'lear view of the
water, are the oldest and largest living members of the dominant
overstory, and often provide a-sparse cover above the nest (Hensel
and Troyer 1964, Lehman 1978, Bangs et al. 1982). .guL9 Eagles
prefer io nest in trees, even if the tops may be dead (Cal1 1978).
i. Southwest Reqion. In the Aleutians, where trees are absent,
ffit on coastl j ne ridges, sea stacks,- and on
hillsides (Gabrjelson and L'incoln 1959, White et al. 1971,
Early 1982). Nests on Amchitka Island are unusual in that
they are virtual'ly rebuilt every year (Sherrod et al. L976).
Murie (1940) found eagles'in the Aleutians. using dried
grasses , steins of wi 1 d parsni p (Heracl euln spp. ) , moss' !,".!P'.
iegetabi e debri s , and dri f twood-Trom EF-e beaches to bui I d
neits. In this region, eggs are occasiona'l'ly laid on bare
ground, with little evidence of nest construction. Nests on
104
B.
Kodiak Island occur in isolated cottonwood stands (Populus
balsamit..uj'lni-iiitii (rrover ind H"nttl. 196s)' .
-Z. Suificenirai n.gion. 0n'the Kenai NWR, the-majority of Bald
ffi cottonwoo-o .tf..: (Popy]yl !*l:f+$q..i'
although urp"n ipoJutut tremuloides) waTaTso conttnon1y used
(Bangs et al . L982).
Reproductive Seasonal i tYgiia Eigle nesting occu-rs at roughly.s.imilar.t'imes in much of the
riui.. "Nesting uitiviiy begins in hiO-to-tate April in Southeast
Ai;;k; (Hensef inJ r.over " 1964, Robard.s_ and Hgdgg.s 1977) 9l'dK;i;k r'iiinJ (chiest 1e?4) and iate Apri.l or early luv,ul9l9_tl',.i;;;;; i;;;;-(hitcr,le 1e82). All birds have seet) incubatins_,bv
the end of May. Incubation lasts about 35 days. The young. Tleoge
iii.. ipproxiirateiy iz-ls days and have fledged most nests by late
August.In the Aleutians, a somewhat different pattern occurs (Bangs'
pers. conrm. ).i: soutnwist Resion. 0n Amchitka, nest bui]ding. may Ptgin asr' ffiinriry (white et al . r97r, sherrod et-al'
i9;6i . -- rgg
-
l ayins tikes pl a-ce .i n li o- ^Iq ' Most easl ets
fledle Uy tle iirs[ week of'Julv (Eultv.1982)
2. Southcentral-Region. 0n the K-enaj Peninsula, lest building
ffid eg-g layin-g occurs in early May. Most
lugr.. tl edge bv tio-to-'l-ate -Jull (Bangs ' pers ' comm' ) '
Reproductive Behavior , _irL __!:-^A;;i;i- aitptuyt thought to be associated with mating or. pair
iormation fravi been o'bserved during the last. few 'weeks prior -to
the northward mi grati on and duri ng -mi grati-on .i tsel f ( I ngram .1965 'c;;d- 1-96bl.- sieeding Batd Eaglis .eltauli.sh.territories during
early spring unO uilororsiy defeld them against other Bald Eagles
until their young bJcome iidependent (Hensil and Troyer 1964).
Age at Sexual MaturitYgira Eag'les utuuirv io not breed before they have acquired -thenfii. fre"ad ana liil"plumage characteristic of adults at about five
;;;;; .iig. ierown 'and Amadon 1968). Four-year-old birds, which
do not have a pure white head, are often classified as mature
Ui.ai-r.gu.at.ti of whether they breed or functjon as adults
(ibid.).
Fecundi ty
In most iegions, only two eggs are produced, but in some areas the
full clutch is often three and,
-rirely, four egg! (B.eebe 1974)'
Aithough all eggs may hatch, often only the-1.argest chick surv'lves
dr
-iriii"i lv ts.ii igiz i . Pioducti on for Ba'l d Easl e popul ati ons i n
ui.Ving poitions of Alaska has been reported to range from .74 to
1.96 y6ung per acti ve nest (Bangs 1 Pers ., -c^ojly.. ) '
i : -Soutiwbst nesi on. Sheirod- et 'al . ( 1976) reported. L-'25^y0ung
ffi- on Amch'itka Island in l97L and 1972- 0n
Kodiak Isiand, the number of young pe.r active nest ranged
from .74 to t.2O Uetween 1963 ana tgZO (Sprunt et al. 1973).
c.
D.
E.
105
2. Southcentra'l Reqi on. 0n the Kenai Nati onal l,li'l dl i fe Range i n
@s et al. (tsaz; found 1.0 and 1.4 eaglets
per active nest, resPectivelY.
VI. FACTORS INFLUENCiNG POPULATIONSA. Natural1. Habitat. Nesting habitat may be potentially limiting. Bald
Faffi as noted, prefer large trees near water. Over 4,000
nest trees have been recorded in Southeast Alaska, and none
was located in a young stand of timber (USDA/USDI L972).
High winds may cause a loss of nesting trees through ryin9-thiow (Truslow tgOt). Windthrow of old growth is relatively
common in Southeast A'laska (USDA 1974).
Forest fires also can destroy nesting habitat. For instance,
Bangs et a'|. (tgAZ) note that eagle nests are absent from
burn areas except where mature stands have escaped extensive
fire damage; over 35% of the boreal forest of the Kenai NblR
has burned in the last 40 Years.
Beavers have been known to cut down nest trees in Interior
Alaska (Ritchie 1982).2. Fratricide. Several observers have noted that fratricide
arnong ::-nestl i ngs i s not uncommon and. may be an important
sourie of mortality among the young (Dixon 1909, Brown ald
Amadon 1968, Bent 1937). Bent reported that frequently on]y
one nestling survives, although two or three or, more rarely,
four eggs may be layed. This appears to be a less 'important
'factor in Alaska, where as many as 35% of successful nests
produce two young (Sprunt et al. 1973).3. Productivi ty:a. Weather. In Alaska, it js not known whether severe
GThF may affect the productivity of eag'les. It is
known that severe storms may result in temporary nest
abandonment, caus'ing destruction of eggs or young (Evans
1982). Postupa'lsky (tgil) believes winter severity has
an impact on the reproductive success of eagles, and
Bangs et al. (1982) believe th'is could be a factor on
the Kenai Peninsula.b. Food resources. Food availability may a'lso influenceproffin-rooa ava'il abi 1 i ty seems to affect the
number of eaglets surviving to fledge in each nest,
rather than the number of pairs that nest (Bangs et al.
1e82 ) .c. Intermittent breeding. Intermittent breeding has been
ffis (Brol ey 1947, Chrest 1964' Brown
and Amadon 1968). Mated pairs may occupy and defend a
territory but not lay eggs that season. The cause is
unknown. Speculations include physio'logical upset'
production of fewer eggs with increasing d9€' or an
i ncrease i n eag'le dens i ty, wi th a resul ti ng decl i ne i n
the food supply (Chrest 1964).
106
d. Accidents. Young eagles may sometimes fall from their
nesffin-d perish. Birds younger than s-even-to-eight
weeks probab'ly w111 not survjve if they.'land in dense
gio"lf' ' where iaut ts cannot reach them (D_unstan 1978) .
ine fi rst f1 i ghts of f1 edgl i ngs are al so hazardous
(Sherrod et al . L976).
e. infertility. A proportion of all eggs laid are infer-
Fle, wflifi may be i result of pesticides, disturbance'
or an inability to reproduce (Brown and Amadon 1968)'
f. Smoke. smoke
-from fires is also a potential hazard to
nffing eagles (Ritchje 1982). This d.isturbance factor
may cause-abandonment of the nest, because they are
unable to see adequatelY.
Disease and parasites.. A variety of diseases and parasites
ffit eag'les in other states. In Alaska,
none occurs frequent'ly or- is considered a limiting factor
4.
5.
6.
(Hughes, pers. comm.).
Predation. Occasional 1y ravens ' crows, magpies,
unnsr.taTlircumstances, gu11s prey on eggs and
(Chrest 1964, Hensel and Troyer 1964, Sprunt and
and, under
sma'll young
Ligas 1964,
Fyfe and 0lendorff 1976).
Mortality. Sherrod et al
ffiY" per year and a
for subadul t b'irds before
Is'land, Alaska.
. (tgZ0) estimated adult mortality
collective mortality of 90% or more
reaching breeding age on Amchitka
B. Human-rel atedA summary of possi b'l e impacts from human-rel ated activi ti es
i ncl udes the fol 1 owi ng:o Pestic'ide pollution of water and/or food
" Reduction of food suPPlYo Disturbance during nesting/abandonment of youngo Destruction of nesting habitato Electrocution on transmission wireso Il legal shooting
(See the impacts of-Land and Water Use volume of this series for
additional information regarding impacts. )
VII. LEGAL STATUSA. Federal
Bald Eagles, their nests, and nest trees are fu11y protected under
the Bali fagte Protection Act of 1940. In addition, Bald. Eagles
in the continental United States are protected as an endangered
species. Bald Eagles in Alaska are not cumently endangered, and
the Alaska subspedies is not on the endangered species list.
State
The state has no additjonal laws regard'ing Bald Eagles.
Population Management
Thit USFWS has; statewide raptor management plan; however, the
Southwest and Southcentral regions have no Ba'ld Eag'le management
programs in progress.
B.
c.
r07
VIII. SPECIAL CONSIDERATIONS
The fol I owi ng probl ems shou'ld be gi ven speci a1 cons i derati on i n Al aslea:o Disturbance - timing clauses
" Silvicultural options for maintaining nest treeso Loss of habitat due to recreational and industrial developmento Prey populationso Water qual ityo Shooting
IX. LIMITATIONS OF INFORMATION
Only limited information on Bald Eagles is available for the Southwest
and Southcentral regions of Alaska.
Specifically, there is insufficient information on the fol'lowing:o Age-specific morta'litYo Longevityo Natal ityo Prey populations - seasonal food itemso Information on the timing of mo1ting is limited and contradictory
(U.S. Army Corps of Engineers 1979)
REFERENCES
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495 pp.
Bangs, E.8., T.N. Bailey, and V.D. Berns. 1982. Ecology of nesti!9 9uld- Eagles on the Kenai National Wildljfe Refuge, A'laska. Pages 47-54 in
l,l.N. Ladd and P.F. Schempf, eds. Proceedings of a symposium and
workshop on raptor management and biology. USDI: USFWS, Alaska
Regional 0ffice. L982.
Bangs, E.E. 1984. Personal communication. l,Jildlife Biologist, USFl..lS'
Kenai NWR, Soldotna, Ak.
Beebe, F.L. I974. Field studies of the Falconiformes (vultures, eagles,
hawks, and falcons) of British Columbia. Occasional Papers of the
British Columbia Provincial Museum No. 17. 163 pp.
Bent, A.C. L937. Life histories of North American birds of prey. Part 1.
New York: Dover Publications, Inc. 409 pp.
Bro'ley, C.L. 1947. Migration and nesting of Florida Bald Eagles. Wilson
Bull. 59(1):3-20.
Brown, L. , and D. Amadon. 1968. Eag'les , hawks , and fa'lcons of the worl d.
New York: McGraw-Hill Company. 2 vols. 945 pp.
Call, M.W. 1978. Nesting habitat and surveying techniques for conmon
western raptors. USDI, BLM, Tech. Note TN-316. Denver Service Center'
Denver, C0.
108
Chrest, H. 1964. Nestjng of the Bald Eagle in-the Karluk Lake drainage on
Kodiak Islind, - Alaika. M.s. Thesis, Colorado State Univ', Fort
Col f ins, C0. 73 PP.
Dixon, Joseph. 1909. A life history of the northern Bald Eag1e. Condor
11 : 187- 193.
Dunstan, T.C. 1978. 0ur Bald Eagle: freedom's symbol survives' Natl '
Geog. 153:186-199.
Ear1y, T.J. 1982. Abundance and distribution of breeding raptors in the
Aleutian lslanas, Alaska. Pages 99-111 jn 1n1.N. Ladd and P'F' Schempf'.
eds. proceeaingi of u tytpoiium and _wor'Khop on-raptor management and
Uioiogy. USOr:"USFWS, Aiadka Regiona'l 0ffjce. 1982.
Evans, D.L. 1982. StatuS reports on twelve rap-tors. usFfis, Special Sci'
Rept., t.lildlife, No. 238. Washington DC' 68 pp'
Fyfe, R.|l|., and T.T. 0lendorff. 1g76. Minimizing the dangers of nesting
studjes to raptors and other sensitive speCies. Can. 1,1ild'1. Serv'
0ccas. PaP. 23. 17 PP.
Gabrielson, I.N., and F.C. Lincoln. 1959'
Manage. Instjtute, Wash., DC. 922 pp'
Grewe, A.H., Jr. 1966. SOme aspects- in the natural history of the Bald
Eag'le in Minnesota and Soitfr Dakota. Ph.D Dissert., Univ. South
Dakota, Vermillion. 72 PP.
Grubb, T.G. Lg77. A summary of current Bald Eagle research in the
Southwest. USDA Forest Service prog' rept' 10 pp'
Hensel, R.J., and tlJ.R. Troyer. 1964. Nestjng studies of the Bald Eagle in
Aiaska. Condor 66(4) :282-286.
Hodges, J.I., Jr. 1982. Bald Eggl.-1gsljlg studies in the Seymour Canal," S6utheait Alaska. Condor 84(1):125-126'
Hughes, J.H. 1984. Personal communication. Nongame Biolog'ist' ADF&G, D'iv'
Game, Anchorage.
Ingram, T.N. 1965. Wintering Bald Eagles at Cassville, wisconsin. Iowa- Bird Life 35(3):66-78.
Kalmbach, E.R., R.A. Imler, and L.tl|. Arnold. 1964' The American eagles'.
and their economic status. USFWS, Bureau of Sport F'isheries and
hlildlife, Wash., DC. 86 PP.
The bi rds of Al aska. t^li I dl i fe
109
Lehman, R.N. 1978. An analysis of habitat parameters and site selection
ciiteria for nesting Bald Eagles in California. Part 1. U.S. Forest
Service, Region 5, San Francisco, CA. 34 pp.
Mindell, D.P., and R.A. Dotson. 1982. Distribution and abundance of
neiting raptors in Southwestern Alaska. Pages II2-I37 j!.t,J.N. Ladd and
P.F. Schempf, eds. Proceedings of a symposium and workshop on_raptor
management and biology. USDI: USFWS, Alaska Regional 0ffice. 1982.
Murie, 0.J. 1940. Food habits of the northern Bald Eagle in the Aleutian
Is'lands, Alaska. Condor 42(4) :198-202.
Postupal sky, S. L967 . Reproducti ve success and. popu'l at_i.or1 trends i n the
bald Eig'le in Michigan. Input. MS. Univ. Michigan Bio'l . Stat. Cited
in Sprunt et al. 1973.
Ritchie, R.J . 1982. Investigation of Ba'ld Eag'les, Tanana River, Alaska'
IgiT-}}. Pages 55-67 in W.N. Ladd and P.F. Schempf ' 9d.s.. - Proceedllgt
of a sympos'ium and wo-rkshop on raptor management and biology. USDI:
USFWS, Alaska Regional Office. 1982.
Robards, F.C., and J.I. Hodges. 1977. 0bservations fron 2,760 Bald Eagle
nests in Southeast Alaska. USFWS, Eag'le Management Study' Prog. rept.
1969-1976. Juneau, AK. 27 PP.
Sherrod, S.K., C.M. lrlhite, and F.S.L. lrJil'liamson. I976. Biolggy of the
gaia Eagle on Amchitka Island, Alaska. Living Bird 15:143-182.
Southern, yJ.E. 1963. !,ljnter populations, behavior, and seasonal dispersal
of Bald Eagles in northwestern Illinois. Wilson Bul'1. 75(1)242-45.
Sprunt, A., IV., and F.J. Ligas. 1964. Excerpts from convention addresses' on the 1963 Bald Eagle count. Audubon Mag. 66:45-47.
Sprunt, A., IV., tl|.B. Robertson, Jr., S. Postupalsky., R.J. Hensel,' C.f. Krioder, and F.J. Ligas. 1973. Comparative productivity of six
Bald Eagle populations. -Pages 96-106 in Transactions of 38th North
Americari witbt'ite and natural resources conference, Washington, DC.
Terres, J.K. 1980. The Audubon Society encyc'lopedia of North American
b'irds. New York, NY: Alfred A. Knopf. 1,109 pp.
Troyer, tlJ.A., and R.J. Hensel. 1965. Nesting-and productiv'ity o.f- Eigles on the Kodiak National Wildlife Refuge, Alaska. The
82(4): 636-638.
Truslow, F.K. 1961. Eye to eye wlth the eagles. Natl. Geog. Mag.
19( 1) :t22-I48.
Bal d
Auk
110
U.S. Army Corps of Engineers. tg7g. The northern Bald Eagle: a literature
survey. u.i. nrfiV Co.pr of Engineers, Env'ironmental Resources Section'
Seattle District.
timber management. USDA Forest Service
Pacific NW Forest and Range Exp. Stat' '
USDA. 1974. Forest eco'logY and
General Tech. RePt. PNI,J-25-
Portland' 0R.
USDA/USDI . Ig72. Bald Eagles 'in Alaska. usFS, Alaska Region; UsFWS'
A'laska Area Office. 14 PP.
USDI . 19g0. Terrestri al habi tat eval uati on cri teri a handbook-Al aska '
USFWS, Div. Ecol. Serv., Anchorage, AK'
Waste, S.M. Ig82. tllinter ecology of .the O.al^d jag-les of^the.Chilkat Val'ley'
Alaska. pa-qes 6g-g1 in !\|.ti. Ladd and P.F. -Schempf, gdl: . Proceedings
of u ,ytpori-r-t unJ *o.f.tf,op on -raptor management and bi o1 ogy ' USDI :
USFWS,
-Al'aska Regi onal Off i ce. 1982 '
westlund, J. 1984. Personal communication. Game Biologist, ADF&G, Div'
Game, Anchorage.
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populaiions-on nmcnitka Island, Alaska. Bioscience 21(tZ) :623'627.
wright, B.S. 1953. The reaction of.Bald Eagles to breeding ducks in New-' " Biunswick. J. l^lildl . Manage. 17(1):55-62'
111
Dabbling Duchs Life Histories and Habitat Requirements- Souttrrest and Southcenral Alasha
I. NAMEA. Cormon Names: Dabbling ducks, puddle ducks, or surface-feeding
ducksB. Scientific Classification1. Fami lY. Anatidae2.Su5:ffiity. Anatinae
3. FiSA.Tnatini
Map 1. Range of dabbling ducks (Bellrose 1976)
c.SpeciETTmmonly 0ccu.rring.ln llq Southwest Re_gi9l
i;-ih;sii,tr,r,eit niglon, ine oauutins duck potglation consists ofIn the Southwest Reqlon' f,ne oaDDllng qucK PUPUI
northern pi ntai 1 . ( Anas acuts ) , mal 1 ard tA:no.ini.n pintait -iA;;i iiut-a), rial'lard' (A, PlSjJflfnctros.)'Americanwigeon-tA..,g'.r'l...*I-:.green.wing"9-!9uf@li
northern shovet.i-' tffivp"ida ) , - ina giawal I (A. sFp-gfa )
(Gabrie'lsen and LincoTn Tgltfl-Lesser numbers of other dabbling
I (4. streperaJ
of oTherTEbTii-snorthern shoveler
duck species such as European wigeon (A. pene]ope), use the area
as well (ibid.).
113
D. Species Commonly 0ccurring in the Southcentral Regi-on
In the Southcentral Region, the dabbling duck population consists
primari'ly of American wigeon, mallard, northern pintail ' and
green-winged teal. Lesser numbers of northern shove'lerr. gadwall,
ind other-dabbling duck species use the region as well (ibid.).
II. RANGEA. Worldwide
Dabbling ducks are cosmopolitan in distribution, with variations
in abuniance related to seasonal changes (Terres 1980).
B. Statewide
Dabbl i ng ducks are abundant and wi de'ly di stri buted seasona'l ly
through6ut the state wherever habitat conditions are favorable
(Gabrielson and Lincoln .|959).
C. Regional Distribution SummarY
To-supplement the distribution information presented in the text,
a series of blue'lined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000,scale,
bui some are at 1:1,000,000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition,
a set of colored 1:1,000,000-sca'le jndex maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.
1. Southwest. In general, dabb'ling ducks are found throughout
TlffiollEhwest Region at elevations below 1,200 ft. Major
concentrations, however, occur in estuaries, lagoons, river
deltas, tidal flats, and lowland ponds. In the Bristol Bay
area, the largest concentrations of dabblers occur during the
spring and fall migrations, whereas Kodiak and the Aleutian
lllanis are imporiant wintering areas (King and Lensink
1971). (For more detailed narrative information, see volume
1 of the Alaska Habitat Management Guide for the Southwest
Regi on. )Z. Soithcentral. Dabb'ling ducks are found in favorable habitat
Th-rougmlTthe Southcentral Region. Because of the lateness
of snow-melt and vegetation growth at higher e'levations, the
most favorable habitat is located be]ow 1,000 ft elevations.
In the Southcentra'l Region, major concentrations occur during_
the spri ng and fa'l I mi grati ons al ong the ti da'l marshes of
Cook Inl et (fi g. 1 ) . Duri ng a I 962 spri ng survey, , ilr
estimated 100,000 birds were observed utiliz'ing the Susitna
Flats area (Sellers .|979). The many estuaries and tide flats
of Prince Willjam Sound (PhlS) and the extensive tidelands of
the Copper River Delta (CRD) are also important concentration
areas. Estuarine and tidal flat areas of PWS and the CRD are
important wintering areas for some species (Tinrm- L977)-.
(Fbr more detailed-narrative jnformation, see volume 2 of the
Alaska Habitat Management Guide for the Southcentral Region.)
114
III. PHYSICAL HABITAT REQUIREMENTS
OjlUSng ducls u.e ue.y mobjle and opportunistic, characteristics that
allow ihem to take a-dvantage of a wide. variety of_habitat lYPes,
Jepending ,pon n..O ald a-vailability (Bellrose .|976)' Preferred
habitat typJi are-llosely associated with water' .ra!-gl!.9 from fresh
water to sa1t anaio. brac[ish water (King and Lensnik 1971). Dabblers'
in
- partl cul ar,- are f requently found on -shal l.ow, smal I - p-o1ds or I akes
borierea by shrubs, trees, oi aquatic plants (Be'l.llgt-. .1976).
Coastat rraui titi - ire al so f requently u.sed by dabb'l 9ll .- . A stqdy of
coastal habitats in Alaska (Arneson l-980) found that dabbling ducks- arq
the most uUiqultous of waterfowl. In the coastal zone' they are. found
most abundanl1y on protected delta water, lagoon water, anq sa]t
marshes, but t6.V-are atso found on eight other habitats. During the
tlrOy, only subtie differences in habitat selection among sp.ecies were
evlALnt. Finiiits, for instance, frequent lagoon island sand much more
than other dabbleri; green-winged teal are o?ten on-exposed mudflats;
and American wjgeon-arL more ab-undant on protected delta water and mud.
ql;irbt-tlglZ) siuOied waterfowl use of different p_1a1t communities at
Chickaloon Oiy-in-rpp.r Cook Inlet (map 2.). Waterfow'l use occurred in
8 of fO typei, with most usq occurring in the marsh, floating marsh'
and mudfla-t conrmunity types (ibid.).
The marsh .orruniiV 'conlains' permanent bracki.sh po.nd.s of various sizes
ana depths bordered by sedges (carex spp.) and .bulrus.hes (scifpus
ipp.l.-'16. ponds .contiin to"oo piErts and are good .feed.'ing,. nesting'
ihb iesting Jdu; tiila.l. The floating marsh community 1s similar but
has fewer,' deeper'open-water areas, gieater p1ant. .species diversity'
and mats of fioating vegetation. 'This type provides large-areas of
iuitab'le habitat, bul leis nesting occurs because there is Iess open
water. The mudflat community was -near the upper limit of the tide and
was utilizla mostly by fali-migrating ducks, resting and feeding in
that type ( ibid. ) .
IV. NUTRITIONAL REQUIREMENTSA. Food SPecies Used
Dabblihg Oucks have a wjde seasonal variety of food items. They
are frig'l"tfy opportunistic and will concentrate on food items most
readi f i aiaifibl. to thet (Peret 1-9.62, Timm t 97! ) . The fo1 l owi ng
food i"tems are known to be uti I 'ized by dabbl i ng .ducks duri ng
portions of the year. This list is incomplete but shows the wide
diversity of food items utilized by ducks'
Animal species - larval and flYing
T6.rms ofTnvertebrates , i ncl udi ng:
Water fleas (Cladocera)
Amphipods (AmphiPoda)
Mayfl ies (EPhemeroPtera)
Dragonfl ies (Odonata )
Watir striders (HemiPtera)
Caddis f'lies (TrichoPtera)
Black flies (Diptera)
Mosquitoes (Diptera)
Snails (Gastropoda)
Plant species - vegetative Parts
tn"-s€E-s oflnumerou s P1 ants'
spp.)
i ncl udi ng:
Pondweeds (Potamoqeton
Cattaits.(ivpha@
Bulrush (Scirpus sPP.)
Sedges (!u.e* spp. )
HorietaiTs CEquisetum sPP. )
A'l gae (Cl adopfrorageae)
Grisses (Graminae)
Mares-tail (Hippuris sPP. )
115
Map 2. Maior coaatal marshes of Upper Cook Inlet
(Campbell 1984).
116
Spiders (Arachnoidea)
Salmon carcasses
(Oncorhynchus sPP. )
Ciusticeffirustacea )
Mo]l usks (Not t usca)
Earthworms (01 igochaeta)
Sti ckl eback (Gaserosteuq
acul eatus
Acorns
Cultivated grains (e.g. ' corn'
rice, wheat, barleY)
Buttercup (Ralg4du! sPP. )
(Bellrose .|976, Bartonek .|972,
Quimby 1972, Sugden .|973)
Dabbling ducks prefer an early season djet high'in animal matter,
changin! to a diet high 1n.p1ant matter as the season progresses
igiiior.f 1972, Sugderi l9i3)'. This seasona'l change i-s 1e'lated to
ioin tn. avaiiaU1iity and the nutritional value of food jtems
iiugo.; lg7s, riapur-1974). The rapi-d early growth of iuveniles
ind- the nutrit'ional requirements of prebreeding and breeding
adutts require food sources high in p.oliin (ili6.i, .Krapu (.1974)
observed inat temale pintails -fed heavily on invertebrates before
and duri ng egg I ayi ng. Esophogea'l contents befor_e qgg ]3Vi ng
iu.rug.O si5 i'Zl .iU a"nimal m'atter, and during- egg- layi,ng 7-7.L. t
it.AU. Invertebrate consumpt'ion decljned sharply after the laying
period (ibid.).
il;i;;.i llbi'zl found that iuvenile American wi.geols .(C'lass, IIa)
contained an average of 66 i ZZf, animal matter. in their esophagi'
*r't..ui-otJ.. juveiiles (Class IIIa and fly'ing) ha! only 12 x.?0%
animal matter - in their diet. Adult American wigeons _-examined
durinq the same study contained an average- of 31 t 34% animal
ritt.i ilUla.l. This represents significantly more animal matter
in tn. ijet ot the adult wigeon than has been recorded (Be'llrose
1g76, Johnsgaad igZS). Sugd6n (.|973) found simjlar results in the
American wi'geon, wi th an jmal food dom'inati ng the di et at f j rst 'Ueing'largeiy replaced by plant food after three weeks of age..
Mal I irds it sb f,ave a hi !h percentage of anim-al materi al i n thei r
eirrv iluion atlti (sarionbk 1972)-. _ A small .sample.of iuvenile
ruifi.AJ iltust IIc) had gg% animal matter in their esophagi'
whi I e a f lyi ng iuvenil e had only 35% animal matter (! bi d-. )_.-
3;;d;r" tr dzji ?orna that iuveiri I e northern pi nta'i1s fol'lowed a
iifiifar'pattern,-tith up to 98% of their early diet comprised. of
animal niatter.'The percentage of plant material in the diet
increased as the ducks grew (ibid.).
1. Cook Inl et (from iinun and Sel I ers 1979).. D-uri ng. the surmer
ffioi t-gZg, u food habits study of dabbling ducks
irirfJ.a ana pintiit) was conducted by _the ADF&G on tida'l
marshes of Cook Inlet (Palmer Hay F1ats, Susitna F]ats, Goose
guv, Cni.latoon Flats, and trioing Bay) (fig. l'.): Four
s.;,6.u or p1;;i; (c;;;i, -s.irp*., !o!o!ggqto!, and Hippuris)
iomprised between BZ and 9-6% of gullet contents'
t17
Seeds of these plants were dominant in both summer and fall'
although tubers of Scirpus paludosus and Potamogeton were
importint in the faTT-ii-ThE-ffiiln'a Flats-diffioG Bay.
Seeds of Potamoqeton and Hippuris were more abundant, and
therefore ffiimportant, TilFTng summer than during fall,
whereas the inverse was true for Carex seeds. Mallards
relied more heavi'ly on Carex and lFheavily on Scirpus
seeds than did pintails.
The Chickaloon Flats and Trading Bay do not have extensive
stands of bulrush (Scirpus validus), and consequently birds
col I ected there were-iEiF! ldevoiif of bul rush seeds. Palmer
Hay Flats contain more bulrush than any other marsh jn Cook
Inlet, and the ducks co1lected there fed more heavily on this
food item than did birds elsewhere. Because of biases in
procedures for co1'l ecti ng and processi ng sampl es , the
importance of anima'l foods was undoubtedly underestimated.
Although not reflected in this study, ducks spent more time
on intertjdal areas as the hunting season progressed. Since
bi rds were re1ati ve'ly i nvul nerabl e whi I e feedi ng on the tide
flats, few were included in the sample. Small crustaceans,
mol'lusks, and algae are probably the major foods consumed by
ducks in the exposed tidal zone.
Copper Ri ver Del ta. Dabb'l i ng ducks on the CRD apparent'ly
ffi vegetation and 'less on seeds than do
maliards and pintails in Cook In'let coastal marshes (ibid.).
Seeds are an important part of the fall duck diet in Alaska
because their high carbohydrate content helps to provide the
energy necessary for migration (Campbe'|1 and Tinm 1983).
The 1981 autumn diet of four species of dabbl ing ducks(pintail, mallard, green-winged teal, and wigeon) wa!
comprised of 36% vegetation, 33/" seeds, and 29% animal
matter. Pintails consumed the greatest amount of seed' as
well as of anima'l matter, followed by mallards and green-
winged teal. Wigeons consumed the least amount of seed andanital matter but the most vegetation (ibid. ). (See
table 1. )B. Types of Feeding Areas Used
Dabbling ducks feed in the shallow waters of small lakes, ponds,
and other bodies of water and at the tide line in A'laska coastal
waters (Tinm 1975).C. Factors Limiting Availabjlity of Food
Lingering snow and ice from a late spring prevent ducls from
foraging in al I areas, especial ly upland areas. Early cold
weather and accompanying ice conditions eliminate food resources
i n most freshwater - areas i n the fal 'l (Rothe' , pers. corm. ) .
Feeding activity under these conditions usually occurs at or along
ice-free coastal areas.D. Feeding Behavior
Dabbling ducks feed either at the surface, where they skim the
water at the edges of the shores and banks, or by "tipping" tail
2.
118
Table 1. D'iet ComPosition of 62
Delta, SePtember through October
Dabbl ing Ducks
1981
on the West CoPPer River
I tem Aggregate % Vol ume % 0ccurrence
Vegetati on
Water buttercuP
(Ranunculus sPP.)
Pondweed (Potamogeton sPP. )
Unidentified grass CRD #3
Mjsc. fo'liage
Seeds
Sedge (Carex sPP.)
Rushes
(E'leochris sPP. & Scirpus sPP.)
Unidentified seed #7
Marestai I ( Hi PPuri s sPP. )
Pondweed (Potamogeton sPP. )
Animal s
Diptera larvae (ChilonoTi4ae,
Ceratopogonidae' | 1 Pu I loaeJ
Unidentified invertebrate eggs
Trichoptera larvae (Brachycentridae,
i itn! pr' i i i aa., Po iYre@ET
Pelecypods (SPhaeri idae)
Gastropods
Stickleback (Gaserosteus aculeatus)
Miscel laneous (Hirudinids, Arachinjds,
0donati ds )
13.6
11. 6
5.1
5.6
12.4
8.1
7.r
3.3
16.9
13.8
10.8
38. 5
16.9
16.9
16.9
13.4
4.2
3.8
3.1
2.5
1.4
1.0
29.2
4.6
23.t
9.?
15.4
3.1
Source: Campbel 'l
--- means no data
and T'imn 1983.
were ava'i 'l abl e.
119
up in shal1ow places, reaching down to obtain food items from the
bottom ( ibid. ).
V. REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat
OabUting ducks general'ly require lowland ponded areas.!ot_nesting;
howeveri some hive been-found over 500 yd from water (Sow]s .|955),
and in areas where choice nesting habitat is limited, nests may be
located up to 5 mi from water (Duebbert 1969):
Nesting p'airs of dabb'lers (and other species) are known to claim
and deieird areas of territory adjacent to their nest site (Sow1s
1955). Defense of these areas by the territorial drake can be
quit6 vigoroqs but usual'ly lasts,on1y until the last egg is laid
and the fema'le starts i ncubati on ( i bi d. ) .
B. Reproductive Seasonal itY
The span of nest initiation depends on local temperatures and
water conditions and varies among species. The initia'l nesting
period usually occurs from mid npiit to mid June (Se'llers '1979).
bucks are persistent nesters and will attempt to nest again,.
sometimes several times, if their first attempt is destroyed
(Sowls 1955). Initial destruction by fluctuat'ing water levels,
mammaljan or avian predators, and man-caused disturbance can be
quite severe, and during some years renesting may account for the
total producti on ( i bi d. ) .C. Reproductive Behavior
Dabblers have new mates each season. Courtship takes place in'late winter and during ear'ly spring. 0n arrival at thejr nesting
grounds, the females-immediately search for a suitable nesting
i'ite and then commence nest construction (Tinnn 1975). As
mentioned, ma'les defend both the females and the nesting territory
(Sowls'1955). This defense lasts until the eggs are layed and the
males retreat to molting areas.D. Age At Sexual MaturitY
A1'l dabb'lers mature atE. Fecundity
one year of age (Timm 1975).
The number of eggs Per
between 1 and 18 €g9s,(iUia.1. (See table 2.)F. Incubation Period
The incubation period varies by species but usually averages
between 21 and 29 days (ib'id.). Hatching generally coincides with
the longest days of the year and the peak production of aquatic
invertebrates in late June.G. Rearing of Young
As soon as the -femal es are wel 'l i nto i ncubati on , the mal es wi th-
draw into flocks by themselves and proceed to molt. They take no
part in raising young (ibid.).
clutch varies among species but ranges
the average being between 6 and 9 eggs
t20
Table 2. Breeding Biology of Dabbling Ducks
Spec i es Nest Locations Mati ng I ncubati on
Clutch Size
Range Average
Sexua I
Matu r i ty
Pi ntai 1
MalIard
Ameri can
wi geon
Ameri can
green-wi nged
teal
Northern
shovel er
Dry ground,
usually away
from water
Ground, edges of
of ponds, much
vari ati on
Dry ground,
away from water,
usually brushy
area
Dry ground, talI
grass, borderi ng
ma rshes
Ho1 lows, on
ground
Late winterl
arrive mated
Late winter;
arri ve on
breeding grounds
mated
May-June
Late winter
May-June,
with two males
occasionally
22-24 days 1-'12 For al l
dabbl ers,
one year
23-29 days,
usual ly 26
1 -15
24-25 days 1'12
21 -23 days 1 -18
2'l -23 days 1 -14
Source: Timm 1975.
VI. FACTORS INFLUENCING POPULATIONS
A. Natural
Species composition and numbers for the Alaska populatjon of
ainUlng Ouiis can change dramat'i9_a11y. Production is influenced
primariTy by spring wealher and flooding. Production is less in
years w] th -
't l'ater'- spri ngs than_ i n . years I',hen slow and i ce
iiiappeir early in the seison. Floodi_ng in ri.ver val,leys or from
storin'tides on coastal wetlands can delay nesting or destroy-nests
and significantly reduce production. Flooding 'in river valleys,
howevei, causes -beneficial effects from nutrient exchanges, which
ferti'liie ponds, increasing the food they produce for waterfowl
(ADF&G 1e8o).
tzl
A phenomenon that has occurred at 1east twice during the last 25
years is the drought displacement of millions of waterfowl from
tfre southern Canada and northern United States prairie potho'le
area to the arctic coastal plain (Hansen McKnight .|964, Derksen
and Eldridge .|980).
During the-first drought period (.|956-1960), several duck species
were recorded in A1aska for the first time or at much greater
abundance than formerly (Hansen and McKnight .|964). In some
areas, waterfowl population indices were three times the average
(ibid.).
During 1977, surveys indicated the highest duck population index
ever recorded in Alaska, a 6l% increase over 1976 and 46% above
the 10-year average (Kjng and Bartonek 1977). The greatest
increase was recorded by northern pintai'ls, which increased I23%
over .|976 and 87% over the 1.0-year average (iUia.1. The 1978
population index was lower but stil'l 5% above the lO-year average
(ibid.).
These drought-related duck population increases did not result in
increased production in Alaska. Although 'l imited evidence
indicates that some displaced duck species will increase their
nesting attempts, there appears to be no related increase in
produciion (Hansen and McKn'ight'1964, Derksen and Eldridge.l980):
ilansen and McKnight (1964) and Derksen and Eldridge (1980) both
concluded that drought-displaced ducks arrive in northern areas
with depleted energy reserves, resul ting in minima'l nesting
success. Also, late arrivals wou'ld have to compete for nesting
sites with already established pairs, adding to poor nesting
success (Calverley and Boag 1977).B. Human-rel ated
A summary of possible impacts from human-related activities
includes the following:o Pollution of water and/or foodo Reduction of food supp'lyo Alteration of freshwater habitato Dredgi ng/f i I I i ngldrai ni ng of wet'l andso Disturbance of fall/spring staging areaso Oi'l i ng of featherso In-f'light hazards (e.g., transmission lines, towers)o Alteration of nesting habitato Lead poisoning in heavily utilized hunting areas
(See the lmpacts of Land and Water Use volume of this series for
additional information regarding impacts. )
VI I. LEGAL STATUS
In Alaska, waterfowl are managed by the U.S. Fish and Wild1ife Service
and the Department of Fish and Game. Waterfowl.are protected under
international treaties with Canada (Great Britain) 1916, Mexico'1936'
Japan 1972, and the Soviet Union 1976.
122
VIII. SPECIAL CONSIDERATIONSA. Mo1 ting
Male dibbling ducks begin flocking by mid June and are flightless
by I ate Junl and eaily Ju.'ly. F1 i ght _ _feathers ale general ly
rlgained by early August (Bellrose 1976), The winq molt of
fetales is delayed to cbincide with the development of the young.
IX. LIMITATIONS OF INFORMATION
Surveys of nesting habitat need to be repeated for the Cook Inlet area.
Information on edologica] requirements is needed, especial]y jn. Cook
Inlet, Alaska Peninsula coastal lagoons, and the Copper River delta.
The ielationship between drought-displaced birds and total annual
production is unknown and needs investigation.
REFERENCES
ADF&G. 1980. Al aska wi I dl i fe management p1 ans: speci es management
policies. Fed. Aid. t^lildl. Research. Proi - W-20-?. 113 pp.
Arneson, P. 1980. Identification, documentation, anq .d.^!ineation of
coistal migratory bi rd habi tat i n Al aska. BLM/0CS contract
No. 03-5-22-69. ADF&G. 350 PP.
Bartonek, J.C. 1972. Summer foods of American u.i9eon,^mallards and a
qreen-winqed teal near Great Slave Lake, N.lr|.T- Can. Field Nat'
aO(+) :ttz--27a.
Bellrose, F.C. L976. Ducks' geese, and Swans of North America.
Harrisburg, PA: Stackpole Books. 540 pp.
Calverley, 8.K., and D.A. Boag. 1977. Reproduc-tive potential in
par-ti and-and arcti c-nest'i ng - popul ati ons of mal I ards and pi ntai I s
(Anatidae). Can. J. Zool 55:1242-125L.
Campbell, B.H., and D.E. Timm. 1983. Waterfowl. lagqs- 9-11 in ADF&G'
Survey-inventory progress report, 1981-1982. Vol .
- 13, Part-5'. Fed.
Aid in hlildl. Rest. Proi. W-22'1.
Derksen, D.V., and hl.D. Eldridge. 1980. Drought-displa.cement -o^f pintails
to the arctic coastal p'lain. J. tli'ldl. Manage. 44(L):224-229,
Duebbert, H.F. 1969. High nest density and hatching success. of ducks on
Souilr Dakota CAP Land-. Pages 218-229 in Transactions of the 34th North
Amderican wildlife and natrual resources conference.
Gabrielson, I.N., and F.C. Lincoln. .|959. The b'irds of Alaska.
Harrisburg, PA: Stackpole Books.
Hansen, H.A., and D.E. McKnight. 1964. Emigration of drought-displaced
ducks to the arctic. irans. N. Am. trJ'ildl. and Nat. Res. Conf.
29:lI9-L29.
123
Johnsgard, P.A. '1975. Waterfowl of North America. Indiana Univ. Press.
575 PP.
King, J.G., and J.C. Bartonek. 1977. A'laska-Yukon waterfowl breeding pair
survey. Pac. Flyway Waterfowl Rept. 78:39-54.
King, J.G., and C.J. Lensink. 197L. An evaluation of Alaskan habitat for--migraiory birds. Unpubl. rept.' USFWS, Anchorage, AK. 46 pp.
Krapu, G.L. 1974. Feeding ecology of pintail hens during reproduction.
Ark. 91 (2) 2278-290.
peret, N.G. 1962. The spring and summer foods of the common mal_lard. (Afas
p. platyrhynchos L.) in southcentral Manitoba. Unpubl. M.S. Thesis,
r+
Univ. B.C., Vancouver.
Quimby, R.L. 1972. Waterbird habitat and use of Chickaloon Flats. M.S.
Thesis, Univ. Alaska, Fairbanks. 86 pp.
Rothe, T. .|984. Personal corsnunication. Waterfowl Biologjst, ADF&G, Div.
Game, Anchorage.
Sellers, R.A. . 1979. Waterbird use and management considerations for Cook
Inlet state game refuges. unpubi. rept., ADF&G, Anchorage.
Sowls, L.K. .|955. Prairie ducks: a study of their behavior, ecology and
management. Harrisburg Pa: Stackpo'le Co. 193 pp.
Sugden, L.G. .|973. Feeding eco'logy of pintail,_ gadwall, -American widgeon' anO 'lesser scaups ducklings. Canadian Wildlife Service rept. Series
No. 24. Ottawa.
Tinrn, D. 1975. Northeast Gulf Coast waterfowl. Pag_es 264'343 in ADF&G''.orp. -A fish and wildlife resource inventory of Prince Willi;fr Sound.
Vo] . 1: hlildlife. L978.
. L977. Waterfowl. Pages 212-265 in ADF&G, comp. A fish and
TTTO1ite resource inventory of the Cook Tnlet-Kodiak areas. Vol . 1:
Wildl ife. I976.
Timrn, D., and R.A. Sellers . L979. Waterfowl. Plgq .19 in ADF&G'-Survey-inventory progress rept., 1978-1979. Fed. Aid in WiTill. Rest.
Vol. 10. Proj. l,l-17-11.
t?4
Diving Duchs Life Histories and Habitat Requirements
South'rest and Southcentral Alasha
Aythyi ni .
1. Fami ly. Anatidae2. Suu-ffii ty. Anati nae3. FiSe:a. Bay ducks orinl and di vi ng ducks.b.ffi
Species Coffi6iiTyTccurring in the Southwest Region
The Southwest ieqion diving duck population is comprised of.the
qreater scauD fRvtnva ma-rita); 'harlequin duck (Histrionigus
nistri!!]ql)i oTaffian .-lgransula hyemalis); sufl scoter
f ierspiiiiiiia) ;' wfiif-winfficoter (I. . .lg?9?
q
...a&$
Map 1. Range of diving ducks (Bellrose 1976)
I. NAMEA. Conrnon Names: Diving ducks, bay ducks' sea ducks
B. Scientific Classification
c.
Aedl arLOI; ai'ffit.ot.. " ([. ;i 1i'* ) ; -
Barrow' s
'-gol defr@deg I anol
r25
(Bucephal a i slarylj ra ) and common gol deneye (9. cl angul a ) ;
umffbneaa @ albeola).; red-bleasted mergan-seT@
serratol) anit-coffioffierg'dnser
-(!.
merganser) ; and Stet ter' sTIEF
ffffift g stel leri ) , Pacific connii6'frJlllil (Somateria mo1I issima
ffi*)-nEllnETiier (!. spectabi I is) (GaE'FGTson anA-LTncdm'
19s9).D. Species Corrnonly Occurring in the Southcentral Regi_on
In the Southcentra'l Region, the diving duck population consists
primarily of Scaup, scoter, goldeneye, buffleheadr.and oldsquaw..
Lesser numbers of canvasbacks (Aythya valisineria), ring-necked
duck (Aytha collaris), .merganseifrfr'd'oihE difi-ng duck species
use thffi!-ion as well (ibjd.).
II. RANGEA. Worldwide
Diving ducks occur in suitable habitats throughout the northern
hemi sphere.B. Statewide
Diving ducks occur throughout the state, generally
and deeper inland bodies of water and along the
1975 ) .
near the 1 arger
sea coast (Tirnm
C. Regional Distribution Surnnary
To-supp'lement the distribution information presented in the text,
a series of bluelined reference maps has been prepared for each
reg'ion. Most of the maps in this series are at 1:250,000 scale,
bui some are at l.:1,000,000 sca'le. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition,
a set of colored 1:1,000,000-scale index maps of selected fish and
wildlife species has been prepared and may be found in the At'las
that accompanies each regional guide.
1. Southwest Alaska. In general, diving ducks are distributed
@uthwest Region at elevations below 1'200 ft.
Major concentrations, however, are found in coastal and
riverine habitats. In the Bristol Bay area, the largest
concentrations of diving ducks occur during spring and fall
migrations, whereas Kodiak and the Aleutian Islands have
their highest concentration of birds during thg winter
(ADNR/USFIS 1983, Gabrielson and Linco]n 1959). (For more
detailed narrative information, see volume 1 of the Alaska
Habitat Management Guide for the Southwest Region.)
2. Southcentral -Alaska. Diving ducks are found in favorab'le
@he Southcentral Region. In general , this
habitat is'located at elevations below 1,000 ft. Large
concentrations of diving ducks overwinter in coastal areas of
Southcentral, in Cook Inlet, especial'ly Kachemak Bay, and in
the many protected bays and estuaries of Prince l^lil'liam Sound
(Pt^lS) (Timm 1975). (For more detailed narrative information,
see volume 2 of the Alaska Habitat Management Guide for the
Southcentral Region. )
L26
III. PHYSICAL HABITAT REQUIREMENTS
k;;;- (p."i.- Corr.) -inAicated that any coasta'l areas within the 60-ft
aeplfr "contour- couta be considered important diving duck habitat.
Di;ing ducks- g.n.*tty prefer protect-ed estuarine habitats, as opposed
to the open oCean (King and Lensink 1971).
Oiuing a-rlf,s-g.n..ufly"frequent the larger and deeper inland bodies of
water and the-sea coait (Tirnm 1975).
IV. NUTRITIONAL REQUIREMENTSA. Food SPecies Used
Diving'Aucfs utilize a wide variety oj plant and animal speci.es.
Animai ip.Cies, however., comprise .the majority o[ their diet
during most of lhe yea" (-Bartonek and Hickey- 196?'.Johnsgard.\97?,
Ol rsctrt tg-6g) . Thi s preference can be rel ated to the hab'itats
diving auifs occupy during most of the year, 909:!91 marine areas'
estuaries, and lai.ber, deeper lakes (Johnsgard 1975)..
Local ry-i6unaint pt anl tobos are al'so uti I i z.ed by di vi ng ducks .
Aquatii pi;;aa, iircluding pondweed (Potamogeton. sPP:)' muskgrass
id[;; t;p:i;. ind butrusi (scirpus sFFJTre extensively used bv
some sPecies ( ibid. ).
Table 'i-preslnts food species known to be utilized. by diving
ducks. This list is inc6mplete but shows the wide diversity of
food species utilized by diving ducks'
gartonEi- una Hicf.y (1-969), s-tudying diving duck food habits in
Canada, reported t'had juvbnlte adult canvasbacks, redheads, and
'lesser's.Jp frJA a high proportion of animal food species in their
spring ina-iu*r.r die[. 'Juveni]e and adult female canvasbacks had
g7% and gZ% animal matter in their diets, respectively (ibid.).
Converselv. adult male canvasbacks had 97% vegetative material in
their surimer djets (iUlO.1. Age and sex class di.fferences are
iioUaUf V itiri UuliUt e to nutri t'i6nal requi rements . f.ut I -co'l I ected
.unuuibi.ii r,io only zlf" animal mattei in their diets (ibid.):
Juvenile redheads have a varied summer diet, with on'ly 43% animal
matter observed in esophageal contents. Adult redheads had a
frigtrer percentlge of anihral-spec_'ies in their sunrner diet, with 86%
and U{", rlspettivety, for'males and fema'les (ibid.). Lesser
scaup
-Jrivenil'es and idults had an average.. of g8- lo 99% animal
matter in their summer diet (ibid. ). The-diets of fall-collected
lesser scaup remained high in'animal matter (ibjd')'
Diving Oucfi species thal are primarily_ associated. with coastal
habitits have i high percentage of an'imal foods in their diet also
(Jonnigi.O fgZS). - fnis catdgory includes eiders, scoters, and
o1 dsquaws.
The common eider has a reported winter diet of mussels (70.3%)'.
uarnaCtei ga.s%), and olher mollusks (24,3%). (Dementiev and
G'ladkov- 1967). ffie surnmer diet of iuveniles. and females showed
that amphip6ds, mollusks, periwinkles, ald crow.berries were
important fbod iources (ibid.)._ Tf'e diet of_king eider appears to
be'similar to the common eider (Johnsgard 1975)'
L27
Juvenile spectacled eiders had a high percentage. of insects in
their summer diet. Pondweeds and crowberries (Empetrum) were
important plant foods during th'is period (Cottam tglf[-
Adult and iuvenile oldsquaws feed extensively on amphipod
crustaceans, mol I usks, i nsects , and fi sh (Johnsgard 1975 ) .
Insects, both larval and flying forms, are important food sources
for juveniles during summer months (ibid.). Crabs, shrimp, and
other crustaceans averaged almost 50% of the food consumed by
adu'lts (ibid.).
Table 1. Plant and Animal Species Utilized by Diving Ducks
Plant Species Animal Species
Cattail (T
Pond I i1y t spp.)
Bur reed (ium spp. )
Green algae
Caddis f1y (Trichoptera)
Midges (Tendipedidae)
Mayf 1y ( Ephemeroptera)
Dragonfly (0donata)
F'lies (Diptera)
Fl 'ies (Hemi ptera )
Leech (Hirudjnea)
Water strider (Corixidae)
Mysids (Mysjdae)
Amphipods (Amphipoda)
Garrnarus spp.
nyaTTeTa spp.
c rayFi sh'-[c ru s ta cea )
Water flea (Daphnia
Snails (Gast@-J
Blue mussel (Mytilus
Mussel (Unio tpil
spp.)
edulis)
Freshwater
shrimp (Palaemonetes spp.)
Clam (Macorna TppF
C'l am (ffiffi 'l ateral i s )Razorffirius)
Crab (Cancer-TFFI)-
Source: Bartonek and Hickey 1969, Johnsgard 1975.
r28
V.
B. Types of Feeding Areas Used
Iiriand diving dlcks rarely feed on land. They genera'lly frequent
ih. larger -and deeper 'inland bodies of water and protected
estuarine habitats '(ibid. ). Marine diving species - frequent
coastal habitats. Shallow coastal waters of bays, inlets, and
estuar.ies, with a variety of substrates, are favored feeding areas
for these tp.ii.t (Johns"gard 1975, Gabrielson and Lincoln 1959).
Most djv.ing'Ouct< siecies have somewhat unique water/substrate/food
preferencei (Rothe', pers. comm.). Buffleheads and mergansers are
irsually assoliated with river systems, especially during winter
(iUiO.j. Eiders, scoters, oldsquaws, a.nd scaups are associated
with coastal marine areas in wjnter (ibid.).
C. Factors Limiting Availability of Food
Lingering snow ind ice from i late spring-may prevent diving ducks
froil utilizing lowland ponded areas. Cold weather, with accompa-
nying ice coiaitions in the fall, p.revents divers from usi19
freshwater areas. Feeding activity under these conditions usual'ly
occurs in coastal marine waters.
The abundanl bogs and muskeg wet'lands common in the Southcentral
Region are aciaic and aie therefore low in productivity.
Nulrients and food species are more abundant in river systems'
deltas, and coastal zones (Rothe' pers. comm.).
D. Feeding Behavior
Oiving"aucks usual'ly dive for their food and will feed submerged.
The d6pths to whjch they dive are generally_ between 2 and 10 ft;
howevei, some may feed ai greater depths. 0ldsquawsl-Io.-examp1e,
have been recordid at depths of over 200 ft (Timm 1975, Johnsgard
1e7s ) .
REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat
Noit Aiving ducks require lowland pond habitats fo.r nesting. Nest
locations -vary according to species (see table 2). The majority
of div'ing ducks build their nests over shallow water in emergent
vegetati 6n or a1 ong the shorel i nes . The common and Barrow' s
ooldeneves and the bufflehead, however, are habitual'ly tree
i.ri.rr" (Timm 1975). ponds with good escape cover and high
aquatic invertebrate populations are preferred.
B. Reproductive Seasonal itY
Noit aiving ducks have-arrived at their breeding range by mid-to-
late May iiUiA.). Nest initjation extends from early-to-1ate
June, aipehaing on the species and weather conditjons, with
scoters generally the last to nest.
C. Reproductive Behavior
Oiving ducks have new mates each season. Birds that have mated
befor! arrival begin nesting as soon as a suitable site has been
selected. Birds that have not mated begin to pair off soon after
arriving at their breeding grounds; they court and then begin
nesting-activities (ibid. ).
129
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D. Age At Sexual Maturity
Diving ducks usual]y mature at two years of age, but it varies by
species ( ibid. ).E. Fecundity
The number of eggs per clutch varies among species. Clutch size
ranges between 5 and 22 egy, the average size of a clutch being
between 7 and 12 eggs (ibid.).
F. Incubation Period
The incubation period varies by spec'ies but usually averages from
19 to 28 days (ibid.).
G. Rearing of Young
As soon as the female is well into incubation, the males withdraw
into flocks by themselves; they take no part in the rearing of
young (ibid.). Brood rearing occurs throughout July and August.
VI. FACTORS INFLUENCING POPULATIONSA. Natural
Species composition and numbers for the Alaska populations of
diving ducks can change dramatically. Production is influenced
primarily by spring weather, flooding, and predation. Production
is less in years with "late" springs than in years when snow and
ice disappear early in the season. Flooding in river val'leys or
from storm tides on coastal wetlands can delay nest'ing or destroy
nebts and s'ignificantly reduce production. Flooding in river
valleys, however, causes beneficial effects from nutrient
exchanges, which fertilize ponds, increasing the food they produce
for waterfowl (ADF&G 1980).8. Human-relatedA summary of possible impacts from human-related activities
includes the following:o Aquatic substrate alteration (e.g., from accelerated aufeis,
mechanical removal )o Chronic debil itation due to ingestion or contact with
petroleum or petroleum Productso Electrocution, contact with powerlines
" Entanglement in fishing nets or marine debris
" Harvest, change in levelo Interference with reproductive behavioro Interruption of ongoing behavior (alarm, flight)o Water level or water quality fluctuations (including changes
in drainage patterns, long-term increase or decrease in water
I eve'ls )
Terrain alteration or destruction (e.g., shoreline habitat,
estuarine, and'lagoon)
Vegetation composition change to less prefemed or useable
s pec'l es
(See the Impacts of Land and Water Use volume of this series for
additional informat'ion regarding impacts.)
732
VI I. LEGAL STATUS
In Alaska, waterfowl are managed by the U.S. Fish and l,Jjld'life Service
ina the Alaska Department of-Fish and Game. Waterfowl are protected
under international treaties with Canada (Great Britain) 1.916' Mexico
1936, Japan !97?-, and the Soviet Union 1976.
VIII. SPECIAL CONSIDERATIONSA. Mo'l ti ng
The relui rements of mo'l t'ing adul ts yary by speci es . Scoters and
o'ldsquaws leave the tundra in mid July to molt at sea, often near
estuaries. Scaup, goldeneye, and other divers will molt on large
j nl and I akes that are perenni al mol ti ng areas . .The mo'l t extends
from mid July to the end of August (Bellrose 1976).
Stel I er' s ei-ders mi grate to thei r wi nteri ng areas o_n Izembek and
other Alaska Peniniula lagoons prior to their molt. The molt
peri od i s variab'l e, rangi ng from August through November
(Johnsgard 1975).
REFERENCES
ADF&G. 1980. Al aska wi I dl j fe management p1 ans : speci es management
polic'ies. Fed. Aid in Wildl . Research. Proi . W-20'2' 113 pp'
ADNR/USFtlls. 1983. Bristol Bay Cooperative Management Plan. Anchorage.
495 PP.
Bartonek, J.C., and J.J. Hickey. 1969. Food habits of canvasbacks,-
redheads, ind lesser scaup in Nanitoba. condor. (71)3:280-290.
Bellrose, F.c. 1976. Ducks, geese, and swans of North America.
Harrisburg, PA: Stackpole Books. 540 pp.
Conant, B., and J.I. Hodges. 1984. Alaska-Yukon waterfowl breeding pair
survey, May 15 to June 12, 1984. USFWS. Juneau, AK.
Cottam, C. 1939. Food habits of North American diving ducks. USDA Tech.
Bull. 643. 139 pp.
Dementjev, G.P., and N.A. Gladkov . t967. Birds of the Soviet Union.
Vol. 4. Trhns. from 1952 Russian ed., Israel Prog. Sci. Transl. USDI
and National Sc'ience Foundation, WA.
Di rschl , H. J . 1969. Foods of I esser scaup and b.1 qe--qi n-g-ed teal i n the
Saikatchewan River Delta. J. l,lildl. Manage. 33(L)277-87.
Gabrielson, I.N., and F.C. Lincoln.
PA: The Stackpole Co. 922 PP.
1959. Birds of Alaska. Harrisburg'
Johnsgard, P.A.
Fitzhenry and
1975. l'laterfowl
t,Jhiteside Limited.
of North America.
575 pp.
133
Don Mi11s,Ont:
King, J. 1983. Pers'onal communications. USFl,lS Bio'logist, Juneau, AK.
King, J.G., and G.J. Lensink. 1971. An evaluation of Alaska habitat for
migratory birds. Unpubl . rept. USDI, Bureau of Sport Fish and
l.lild'life. Washington, D.C. 72 pp.
Tinm, D. 1975. Northeast Gulf Coast waterfowl. Pages 264-343 in ADF&G,
comp. A fish and wi'ldlife resource inventory of Prince hlit'liam Sound.
Vol. 1: t.lildlife.
134
Geese Life Histories and Habitat Requirements
Soutlrrest and Southcentral Alasha
q
...6@t
Map 1.. Range of geese (Bellrose 1976)
C. SpeciET-llommonly 0ccurring in the Southwest Region
i[-i6.-souil*.ri Region, 6oose populations are comprised primarily
of the Paci f i c f lyiay 'polut ati'on of greater whi te-fronted ggqle
(Anser al bi irons ) ;' ttri bm'pero. goose (-Ch* calagi ca) ; the -Paci f i c
otffiuf*ifg.-.nia berniila nig-ricans); andTFree races of Canada
gooi., the 'cffin a6*-('eialta canadensi s WI:Aleutian canaal''Iil;. iq:-t t"euiopaiETaT, an<lffir'iltanada
I. NAME
A.
B.
Conmon Name: Geese, brant
Sci ent'if i c Cl assi f i cati on:
1. Family. Anatidae.2. S6ffii ty. Anserinae.3. Fi5e--Anserini.
135
goose (B. c: taverneri) (eaUrielson and Lincoln 1959). .Thq lesser
snow9ooSe(@)occursduringmigration(ibid.).D. Species Common.il doffig fr the Southcentra'l Region
Goose species that commonly occur in the Southcentral Region
include'the lesser Canada goose (Branta canadensis parvipes)' the
dusky Canada goose (q. C. -occidei'[ETiT), possT$fy TF-e-l/-arcouver
Canaia goose (q. q. -lrlva);TFe-m-e white-fronted goose (Anser
albifrons gambe-li)l and, during migration, the lesser snow goose'
Eeaffitrfre-Tronted goose, and cackling Canada goose (Gabrielson
ind Lincoln 1959; Rothe', pers. comm.).
II.RANGEA. Worldwide
Geese are found in nearly all northernB. Statewide
Geese are found throughout the state
avai'labl e.
temperate and arctic zones.
where suitable habitat is
C. Regional Distribution SummarY
To supplement the distribution information presented in the text'
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at l:250,000 scale'
bui some are at 1:1,000,000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition,
a set of colored 1:1,000,000-sca1e index maps of selected fish and
wildlife species has been prepared and may be found'in the Atlas
that accompanies each regiona'l guide.
In general, geese are distributed throughout the Southwest Region
at elevatiois below 500 ft (Sellers, pers. conrm.). In
Southcentral Al aska, geese are found i n sui tabl e habi tat at
elevations up to 1,000 ft (T'imm 1977). Estuaries, lagoons, river
del tas , marshes , and t'i del ands , however, support the 1 argest
concentrations of geese.1. Southwest. The largest concentrations of geese occur in the
EFiffiT-Eay and Alaska Peninsula areas during spring and fall
migrations; Kodiak and the Aleutian Islands remain important
wintering areas for some species (Gabrielson and Lincoln.|959, ADNR/USFWS .|983). (For more detailed narrative
informatjon, see volume 1 of the Alaska Habitat Management
Guide for the Southwest Reg'ion.)2. Southcentral. The 'largest concentrations of geese in the
Sdmh'ceilmT Region occur during spring and fal'l migrations.
The tidal salt marshes and extensive mud flats of Cook Inlet,
the numerous small mud flats of Prince l,ljlliam Sound (Pl,lS)'
and the large alluvial f'loodplain and delta of the Copper
River all provide important spring and fa1'l habitat for geese
(Timm 1977).
Additional'ly, important world populations of the tule goose
and the dusky Canada goose are found in Cook Inlet and the
Copper River Delta (CRD), respectively. The tule goose has
136
been found nest'ing along the west side of Cook Inlet' which
is the only known-breeding area. This subspecies winters in
northern California (Timm 1975).
The world population of the dusky Canada goose is known to
breed only on the cRD. The wi nteri ng area for thi s
subsoecjes-is in the Willamette Val'ley, Oregon, and southwest
Washington (ibid.). Additionally, Canada-geese breed'in the
small "bays ind islands of PWS. This population is generally
believed to be a small population of Vancouver Canada goose
(8. c. ft&q) (ibid.).
(For roT-AeiaileO narrative information, see volume 2 of the
Alaska Habitat Management Guide for the Southcentral Reg'ion.)
III. PHYSICAL HABITAT REQUIREMENTSA. Southwest
Geese in the Southwest Region are usually found where lagoon water
and embayment habitat are plentiful, particularly on the north
side of ttre Alaska Peninsula. Brant are primari'ly restricted to
lagoon water where eelgrass 'is found. Canada and snow geese use
upiands,'lagoons, and alluvial floodplains, whereas emperOrs use
ligoon islariO sand and protected delta mud (Arneson 1980).
B. Southcentral
Geese are found in a wide variety of habitats, but are most cOmrnon
in al I uvial f1 oodpl ains, 1 agoons, and tidal mudfl ats. Canada
geese, particularly in the Southcentral Region, u.se alluvjal
itooOptains and coastal salt marshes extensively during their
migrat.ional stopovers (ibid.). Additjona'|1y, !h. saljne
sedge-grass flat habitat of Cook Inlet 'is thou.ght to.b_e important
nesIin! habitat for tule geese (Timm 19_82) (See.tab]es 1 and 2
for additional informatjon on habitat preferences.)
IV. NUTRITIONAL REQUIREMENTSA. Food Species Used
Geese ire predominantly vegetarians and consume the leaves, roots,
and seeds bt a wide variety of plants. Cultivated grains comprise
a larqe percentaqe of their diet in wintering areas of the
contin6ntal U.S. igeltrose 1976). Along coastal areas, geese are
known to feed on mollusks, crustaceans, and other anjmal materials
(taUte t) (Terres 1980). Black brant feed almost exclusively on
eelgrass'(Bellrose 1976). During fal_l migration on the Alaska
Peninsula, Canada geese feed extens'ively on crowberries (Erlpetrum
spp.) (Rothe,, peis. comm.). (See tables 1 and 2 for further
information on food.)B. Types of Feedjng Areas Used
GLese are oppoitunistic and forage in areas providilg_-plentiful
food suppliei. Coastal salt marshes and adiacent shallow water
areas, tuttivated fields, freshwater marshes, and a vari.ety of
other habitats all provide feeding areas for geese (Johnsgard
1e75).
137
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C. Feeding Behavior
Geese are essentially grazers and crop vegetation with theirbil'ls. During spring, tubers and rhizomes are often dug uP, andin fal I berries are often selected. When eating submerged
vegetation, they reach below the surface with their head and neck,
tai'l ti pped up, s imi l ar'ly to dabbl 'ing ducks . Geese feed primari 1y
i n the ' early morni ng and 'late af ternoon (taU'le t ) (Timm I 975) .
Except during nesting, geese feed social'ly in flocks that move and
react to disturbance as a unit (Johnsgard .l975).
REPRODUCTIVE CHARACTERISTICSA. Reproduct'ive Habi tat
Nesting sites vary by species, but there are three standard
prerequisites for al'l geese: 1) proximity to water, 2) cover for
the nest itself, and 3) an exposed vjew of the surrounding areafor the incubat'ing bird (Be11rose I976, Johnsgard 1975). (See
tables 3 and 4.)B. Reproductive Seasonal ity
The span of nest initiation, which begins in early May, varies
among species and is dependent on weather conditions. In years
when snow cover and cold cond'itions persist later into the season'
nesting efforts may be delayed for several weeks (Johnsgard .|975).
C. Reproductive Behav'ior
Geese appear to form pair bonds that remajn steadfast throughoutlife, but when separated by death, the survivor seeks a new mate.
Most species of geese return to the same breeding grounds or
nesting colonies each year, where they establish a territory prior
to nesting. The size of the territory varies by species and
within the species, accord'ing to the demands made upon the
avai'lable space (ibid.). Brant and snow geese are colonjal
nesters, and their nests may cover large areas. Some Canada goose
subspecies and emperors may nest 'in loose aggregations, whereas
white-fronted geese are solitary nesters (Rotne, pers. conrm.).
(See tabl e 2.)D. Age at Sexual Maturity
0n the average, geese reach sexual maturity at two years of age,
although the majority do not breed unti'l their third year (Terres
1980, Bel I rose 1976) .E. Fecundity
The number of eggs per clutch varies among species but ranges
between 1 and 12 eggs, the average size being 4 eggs (Johnsgard
1e75 ) .F. Incubation Period
The jncubation is conducted so'le'ly by the female, with the male on
guard nearby (Terres 1980). The incubation period varies by
ipecies but usually averages between 25 and 30 days (ibid.).
G. Rearing of Young
Both parents are attendant to their young, the ma'le principally
assuming the role of guarding them from predators (Bellrose 1976).
140
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VI. FACTORS INFLUENCING POPULATIONS
A. Natural
Species composition and numbers of geese in areas of A'laska can
cirange-dru*itica]1y. Production is influenced primarily. !V :Pring
weather and flooding. Production is less in years with "late"
springs than'in years when snow and ice disappear.early in !h9
s.uson. Flooding in river valleys or from storm tides on coastal
wetlands .un Oeiay nesting or -destroy nests ang significantly
reduce production. Flooding in rjver va'l1eys,. h-owever' causes
benefici'al effects from nutrient exchanges, which fertil i-ze.P94:
and thus increase th; food they prod-uce for waterfowl (ADF&G
1e8o) .
The 1.964 earthquake uplifted parts of the cRD by -as much as 1'89
m. fnis nas ippur.ntiy result'eO in drier, less saline soils, with
subsequent ch'ahqes i n vegetation communi ties on the del ta '
i ncf u<iing
-
tfrose uti I i zed fol nesti ng by. dusky Canada g.eese ' An
'increase in the use of sedge as a nes{ing cover tyPg during !h9
mid .|970,s was due to 1) a-n increase in the suitabil i-ty o-f that
cover' tvp. ii.tj - flooding) a1d 2) .high population levels and
increasl'd nesting density,-which may have caused nesting -to occur
i n r eii- iavorabl6 habi tal' ( Broml ey -1976) . In addi ti on, i ncreased
nest fredation, particularly by mammalian pre-dalor:' alpears to be
a taiioi in tnd reduced riesiing success of dusky Canada geese
(Campbell l9B3).B. Human-rel ated
The ausr<v canada goose popu_]ation, which wi.nters almost
exct usl veiy i n the Wi'li amette' Vi'l I ey, 0regon , i.s probably. the,T9:!
heaviiy ha-rvested Canada goose population in North America (Timm
fg7Sl." The interm'ix'ing of wintering populat'ions_ of the more
numerous lesser Canada g..t. (g. g. iarvibes an-d- 9. C. taverrli )
with the less abundant dusky Canada goose compl_'icateS censuslng
and harvest management. A1{hough duskys-are dil.uted among more
numerous subspeciis, their high vulnerability to hunting causes a
Oisproporiionit.tV irigh ha1v91p of this subspecies compared to
others (SimPson and Jarvis 1979).
Other truman'-retated factors influencing goose populations include
lnt tillillln;rorrrate arteration (e.g., from accelerated aufeis,
mechanical removal )ct.onic debil itation due to ingestion or contact wjth
petroleum or petroleum Productsboitision wi'th vehicies (including automobiles, boats'
aircraft) or structures: ilislli:ili:?,i:,iiinii:,:ihli:iiiii:.Hil:, vehic,e n.ise,
human scent)o Interference with reproductive behavior
" Interruption of ongoing behavior: alarm, flight
Terrain' alteration-or iestruction (e.g., rapior cliffs)
143
Vegetati on compos'iti on change to 'less preferred or useabl e
spec'ies
Witer level or water quality fluctuations (including changes
in drainage patterns, long-term increase or decrease in water
levels)
(See the Impacts of Land and Water Use vo'lume of this series for
additional information regarding impacts.)
VI I. LEGAL STATUS
In Alaska, waterfowl are managed by the U.S. Fish and Wildlife Service
and the Alaska Department of Fish and Game. They. are protected under
international treities with Canada (Great Britain) 1916' Mexico 1936'
Japan '1.972, and the Soviet Union 1976.
VIII. SPECIAL CONSIDERATIONS
Mol ti ng
The fiist geese to molt are usually the subadults, followed by mature
breeders that failed to nest successful'ly, and then by successful
breeders. For breeding birds, the molt is initiated when the goslings
are between one and three weeks o1d, varying by species. Geese are
il tghtt.ss for approximate'ly three to foui weeks (Bel 1 rose 1976).
During. this period, geese are vulnerable to predation- and are very
sensi['ive to disturbance. Molt'ing f]ocks are often found. on 'large
lakes and protected coasta'l waters away from nesting areas (Johnsgard
1975, Bel I rose 1976) .
IX. LIMITATION OF INFORMATION
The breeding grounds of the tule goose has only recently been.partially
del i neated, - lnd addi ti onal data on nesti ng areas and habi tat
requirements are needed.
Studies to determine mammalian depredation of dusky Canada geese nests
are ongoi ng and wi I I conti nue. Addi ti onal studi es to determi ne
utilizaiion-of new nesting habitat created by the 1964 earthquake are
being conducted by the ADF&G and the USFWS. The importance of Cook
Inlei and Alaska Peninsula staging habitats needs to be further
described. Banding studies and research on nesting areas needs to be
increased substantially to determine movements and mortality sources.
REFERENCES
ADF&G. 1980. Alaska wildlife management plans: species management
policies. Fed. Aid in Wi'ldl . Research, Proj . W-20-2. 113 pp.
ADNR/USF!r|S. .|983. Bristol Bay Cooperative Management Plan. Anchorage.
495 PP.
Arneson, P. 1980. Identification, documentation, and delineatjon
coastal migratory bi rd habi tat j n Al aska. BLM/OCS contract
03-5-022-69. ADF&G. 350 PP.
of
No.
t44
Barry, T.W. 1966. The g-ee-s-e of the Anderson R'iver delta, Northwest' ierri tori es . Ci ted i n Bel'l rose 1976.
Bellrose, F.C. Ig76, Ducks, geese, and Swans of North America'
Harrisburg, PA: Stackpole Books. 540 pp.
Bromley, R.G.H, 1g76. Nesting and habjtat studies of the dusky canada
;;;r;'iiiranta canLde_qlls ggddentalis.) on the Cooper River delta'
Ilaska.'lSrfies]s;Unlv. ffiskaF-irbanks. 81 pp'
Dau, C. 1983. Personal communication. t,Jildlife Biologist, USFlr|S, Cold
Bay' AK.
Einarsen, A.S. 1965. Black brant: sea goose of the Pacific coast. cited
in Bellrose 1976.
Eisenhauer, D.I., and D.A. Frazer. L972. Nesting e991ogY.9f the emperor-'-- ;;;;.' fpniii.i. canagica Sewastianov) in the Kokechik Bav region'
Alaska. Oepi. Fot. Co"nserv., Purdue Univ., West Lafayette, IN' 82 pp'
Gabrjelson, I.N., and F.C. Lincoln. .|959. Birds of Alaska. Harrisburg'
PA: Stackpole Co. 921 PP.
Lebeda, c.s. 1980. Nesting and rearing eco-1ogy of .the vancouver canada-----goor. in nJmiiafty lstinO in Southeast Alaska. M.S. Thesis, S. Dak.
State Univ. 77 PP.
Johnsgard, P.A. 1975. Waterfowl of North America. Don Mi'lls,ort;
Fitshenry and Whjteside, L'imited. 575 pp.
1977. Waterfowl. CZM rept. on Cook Inlet-Kodiak.
. I1BZ. Report of survey and inventory activities - waterfowl.
-EiI.
Aid in wildi. Rest. Proj-. w-19-2, Job No. 11.0. 48 pp'
. 1984. Personal communi cations. Regi ona'l Mgt. Coordi nator 'TF&G, Div. Game, Anchorage.
Lebeda, C.S. 1980. Nesting and
goose jn AdmiraltY Island in
State Univ. 77 PP.
Mickelson, P.G. Ig73. Breeding bio'logy of cackling geese (grallq
canadensj s minima Ridgway)- and associated species on the
Yu[on-KusRokw]mETta,TTiTk'll Ci ted i n Bel I rose 7976.
Rothe, T. 1984. Personal communications. Waterfowl Bio'logist' ADF&G, Div.
Game, Anchorage.
Se'llers, R.A. 1984. Personal communications. Area Mgt. Biologist, ADF&G,
Div. Game, King Salmon.
rearing ecology of the Vancouver Canada
Southeist Alaska. M.S. Thesis, S. Dak.
145
Simpson, S.G., and R.L. Jarvis. 1979. Comparative ecolo,gy of severa'l
subspecies of Canada geese during winter in western Oregon. Pages
223-241 in R.L. Jarvis and J.C. Bartonek, eds. Management and bio]ogy
of PaciflC flyway geese. OSU Bookstore, Corvallis. 346 pp.
Terres, J.K. 1980. The Audubon Society encyclopedia of North American
birds. New York: Alfred A. Knopf. 1'109 pp.
Tinrn, D. 1975. Northeast Gulf Coast waterfowl. Pages 264-343 in E.G.
Klinkhart, €d. A fish and wi'ldlife resource inventory of Prince t.Iilliam
Sound. Vol . 1: Wi I dl i fe.
146
Seabirds Life Histories and Habitat Requirements
Soutftrest and Southcentral Alasha
Map 1. Range of seabirds (ADF&G 1973, Sowls et al. 1978)
I.
II.
NAME
Seabirds known to occur in Alaska are sepa.rated into the following
qeneral cateqories: albatrosses (Diomedeidae), shearuaters and fulmars
lF;;;;t l;iiA;;) ,-ito*-petrel s (Hydrouatidae) , connoranls (Phalacrocor-
;;iA; j ,-griii' ina ieini ( t-ari die) , and al ci ds (Al ci dae )., whi ch i ncl ude
ilrE;i'fultrerots, murrelets, auklets, and puffins (Quinlan' pers.
corm.;-Soits et al. 1978; Nelson 1979).
RANGEA. tr{orl dw'ide
Approximately 260 species of seabirds occur worldwide. Their
rihge extends virtuilly from pole-to pole and throughout the
expanses oi the worldis oceani. Some species of seabirds mqy
occur anywhere on the open ocean; however, they more commonly
r47
B.
occur near favorabl e areas of current upwe'l 'l i ng and convergence.
These areas provide concentrated food Sources for large numbers of
seabirds (Nelson 1979).
Statewi de
At'least 65 species of seabirds migrate, breed, or visit along
Alaska's coastiine and adiacent waters (Trapp' pers. conun.).
Seabird colonies appear to be most numerous in the Gu'lf of Alaska'
along the A'laska Peninsula, in the Kodiak archipelagg,.and in
Prinie trtilliam Sound (Ptrls). In the Bering and Chukchi seas
region, fewer co'lonies are found; however' all are vgry large'
maiy containing breeding populations exceeding a million birds
(King and Lensihf tgzt, Sowls et al. 1978).In late fall, most seabirds migrate south, and populations in
Alaskan waters become much reduied from those of surmer (ADF&G
1e78).
Regional Distribution SummarY
To-supplement the distribution information presented in the text'
a series of b'luelined reference maps has been prepared for each
region. Most of the maps in this series are at L:250,000 scale'
bul some are at 1:1,000,000 sca'le. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition,
a set of colored 1:1,000,000-scale index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.
Because of a greater variety of favorable habitats in Southwest
and Southcentral A'laska, seabird popu'lations there exhibit greater
species diversity than those found in the remainder of the state
(iuia.1.
1. Southwest Reqion. In Southwest A]aska' over 560 colonies or
ffi, with breeding populations i.ncluding over
23 splcies of seabirds, have been recorded (Sowls et al.
1e78).In Southwest A]aska, the common murre represents over half
the total population of colonial birds. Other species of
importance include the black-legged kittiwake, tufled puf!!n'
peiagic cormorant, and glaucous-winged gull (ADNR/USFhlS
igAS). (For more detailed narrative information, see volume
1 of the Alaska Habitat Management Guide for the Southwest
Region and the USFWS Catalog of Alaskan Seabirds Colonies
[Sowl s et al . 1978] . )2. Southcentral Reqion. In Southcentral Al aska ' over 216
ffit least 26 spec'ies, have been documented(ibid.). The maiority of these colonies occur in the Pt,lS
area (including Middlelon Island and Blying Sound), with over
407,000 birds nesting there during the breeding season.
Along the southern outer Kenai Peninsula coast and the lower
Cook- Inlet area, over 73 colonies are documented (ibid.)'
with over 43,000 breeding birds.
c.
148
In Southcentral Alaska, the black-leg-ged. kitt^'iwake is the
most abundant speciii 'ot nestinq seabjras' gther seabird
,p..i., -
"i ir, I i;;g --breedi n.g poput ati ons !n southcentral
Al aska i ncl ude tiiteJ purti n, ' cornmon murre r ilrd pel agi c
cormorant. A ,ruii -.rt Jnv of ' fork-tai I ed storm petrel s i s
located on Wooded Island in PWS'
(For more detairea-narrative jnformation' see volume 2 of the
Alaska Habitat manig.*"nt Guide for the Southcentral RqS!01
and the usFWS catil6g oi niistcan Seabird colon'ies Iibid.]')
computeri zed ai siriduti on qnd abundance i nformation i s
.ilii;i.-iro, tt. usrr^rS (sowt s , pers. connn) .
III. PHYSICAL HABITAT REQUIREMENTS
Alaska.svastcoasta]zoneandcontjnenta]shelfprov.ideabundant
feeding, molting, migrating] una-ninlering. habitat for seabirds' These
marine habitats can be .utu'golii.o ui ins-hore, nearshore, and offshore
waters (includ.ing mid .onll..riit- -rn.tt_, outer continental shelf'
shelfbreaf,-ana oieanic waters)' (See table 1')
IV. NUTRITIONAL REQUIREMENTS
(See table 1.)
V. REPRODUCTIVE CHARACTERISTICS
A. ReProductive Habitat
Nestinq habitat for seabirds in Alaska is largely confined to
i sr anil , "Tl'i"if",
,
' "bt r-itt ,. ind beaches of the coastal zone.
seauirli, r,o".uli^, rho"-ionsiderable flexibility jn a_daptirg .to
avai I uui. n.iti ng hauiiit by ulj 'l i zi ng a w j de . Yqli etv of habi tats '
incl uding man-mao. ttruliri".r-(ir,ip*r6.[s, bui'l ding ledges,. etc.,).
laturi j i,"iit ng f'uUi tJ wi tfri ri thb coastil zone incl udes boul der
rubble, talus slopes, .0.I cliffs.,- rock crevjces, cli'ff ledges'
so'il buffows, and ir ui- gtJuna (trapp-'- pers ' -t9T*') ' A lgn
seabi.ii', lr.f' ut iaegers, giau.oi,s gutl,'mew gu'11' and arctic
tern , are wi de'ly di stiiUut6O ihroughoui tne i nteri or a'l ong 'l akes '
streami, and jn areas oi moist tund''ra (taute 1).
VI. FACTORS INFLUENCING POPULATIONS
A. Natural
Diseaie and parasites have the potentia'l to kill malY 9itd:'
attfrouifr-tira!-;i ihis phenomenon is in its infancv in Alaska
(ibid.).tncr.iling gul I populations could cause substantial damage
(tfrrougtr "fooi-robbi.6-.ii -.gg inJ, young predation) to specif ic
.oronixi;*.i.r"lruin., teins and puffind), as they have on the
Atlantic cbast (ibid' ) 'B. Human-related
Predators , mai n'lY
1800's and earlY
foxes, introduced for fur-farming in tqt l?!:
1900's have had a devastating and long-lastlng
149
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impact on Alaska seabird colonies throughout Southcentral and
Solthwest Alaska (ibid. ).0il and gas developmental activities and the re'lated possibility
of marin6 oi1 pollution pose a threat to seabirds. If properly
regulated, however, offshore oil and gas development may not
seierely impact seabirds (ibid.).
Corrnercial 'exploitation of North Pacific fish populations may
resu'lt in a serious reductjon in fish numbers, which in turn might
reduce the food supply of seabirds (ibid.).
Toxic chemical contam'ination of seabirds is a serious threat. The
widespread distribution of a variety of pollu.tants in marine
ecosystems affecting seabirds is well documented (Ne1son 1979).
In Alaska, human disturbance in the form of tourism has not yet
been a problem (Trapp, pers. comm. ). Properly organized 3ld
regu'lated visits to seabird colonies by tour groups can actual1y
beiefi t seabi rds by promoti ng publ i c support for managerial
efforts (ibid.).
VI I. LEGAL STATUSAll seabirds are protected by the Migratory Bird Treaty Act of 1918.
Seabirds in Alaska are managed by the U.S. Fish and hlildlife Service.
VIII. LIMITATIONS OF INFORMATION
Current abundance information for many species and some areas is
needed: outer Aleutian Islands, some areas of Pl.lS' and Southeastern
Alaska.
Nesting habitat and behavior of some species, especially marb'led and
kittlitz's murre'lets, is little known.
ADF&G, comp.
comp. I .
ADNR/USFI.JS.
495 pp.
REFERENCES
1978. Alaska,s wildlife and habitat. vol.2 [E.G. K]inkhart,
74 PP. + maps.
1983. Bristol Bay Cooperative Management Plan. Anchorage' AK.
King, J.G., and C.J. Lensink. 1971. An evaluation of A1askan habitat for--m'igratory birds. USDI, Bureau of Sport Fjsh. and Wildl. 26 pp.
Nelson, B. 1979. Seabirds - their biology and ecology. New York: A&tll
Pub'l i shers. 219 PP.
Quinlan, S. 1984. Personal communications. Nongame Biologist, ADF&G, Div.
Game, Fairbanks.
Sowls, A.L. 1984. Personal corrnunications. l,lildl ife Biologist, USFlr|S,
Anchorage, AK.
154
Sowls, A.1., S.A. Hatch' and - C.J. Lensink' 1978'--' -ieabird'colonies. u5ut, USFWS, Anchorage, AK' 254
Terres , J. K. 1980. The Audubon soci ety _encycl opedia
birds. New York: Alfred A. Knopf' 1,109 pp'
Trapp, J. 1984. Personal cornnunications. l|lild.|ife
Anchorage, AK.
Catal og of A'l as kan
pp.
of North American
Biologi st, USFWS,
155
I.
II.
NAMEA. Conrnon Name: TrumPeter swan
B. Scientific Name: Cygnus buccinator
RANGEA. l,|orldwide
The present range of the trumpeter swan .i s only a vesti.ge. of the
once vast regidn of North Ainerica that it frequented in both
suruner and winter (Bellrose 1976).
1. Breedinq .ingi. The trumpeter swan breeds in central and
ffiia,British'Columb.ia,Alberta,'southwestern
Montana', una-lf,oriting (Gabrielson and Lincoln 1959).
Z. Winterinq area!. The southern portion of the trumpeter swan
iioptt ore or less nonmigratory, whereas the northern
Ttumpeter swan ufe History and Habitat Requirements
Southcentral Alasha
Map 1. Range of trumpeter swan (Bellrose 1976)
r57
portion migrates to the coast of southeastern AIaska and
British Columbia, Washington, Oregon, Idaho, Montanar ard
Wyoming (ibid. ).B. Statewide1. Breeding range, According to King and Conant (1980), nestingffiFffiswans in Alaska are distributed along the North
Pacific coastal plain from Yakutat to Cook Inlet, through the
forested valleys of the Copper, Susitna, and Yukon rivers to
the vicinity of the Arctic Circle at elevations below 3,000ft. (See map 1 in the trumpeter swan Distribution and
Abundance section of vol ume 2 of the guide for the
Southcentral Region. )2. t,lintering areas. Trumpeter swans that breed in Alaska winter
ETorr:-theTETfic Codst from the Alaska Peninsula to the
mouth of the Co]umbia River (gettrose 1976).C. Regional Distribution Summary
To supplement the distribution information presented in the text,
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale,
but some are at 1:1.,000,000 scale. These maps are available for' review in ADF&G offices of the region or may be purchased from the
contract vendor responsib1e for their reproduction. In addition,
a set of colored 1:1,000,000-scale index maps of selected fish and
wi'ld1 i fe speci es has been prepared and may be found i n the Atl as
that accompanies each regional guide.1. Breeding range. The trumpeter swan is a 1oca11y common
sumnrer TeSlilEnt of the freshwater areas of the northeastern
coast of the Gulf of Alaska, an uncommon migrant and visitorin Prince William Sound, and an occasional visitor along the
northwestern coast of the Gulf of Alaska (Timm 1975).2. @. Birds winter on the open, freshwater
ouTlffiT-M'k' Lake and Martin Lake near Cordova and on
Skilak Lake on the Kenai Penninsula if suitable conditions
exist (Timm 1975i Spraker' pers. conm.).
(For more detailed narrative information, see volume 2 of the
Alaska Habitat Management Guide for the Southcentral Region.)
III. PHYSICAL HABITAT REQUIREMENTSA. Aquatic
Trumpeter swans prefer secluded regions, where they frequent
shallow bodies of water (Tirmn .|975).
Along the coast in late suruner and ear'ly fall, large numbers of
trumpeter swans congregate on ponds and marshes (ibid.). Birds
winter on ice-free freshwater outlets, although sometimes they are
temporari'ly driven to salt water during extremely cold periods
when freshwater 'locations freeze (ibid.). Palmer (1976) defines
wintering habitat of trumpeter swans in Alaska as unfrozen ponds'
lakes, sluggish-moving waters, marsh meadows, and inner brackish
reaches of coasta'l fjords and bays (see section V.A. below for a
discussion of additiona'l water requirements).
158
IV.NUTRITIONAL REQUIREMENTS
A. Food SPecies Used
Adult trumpeter swans prefer wild ce'lery (Angel jca.luci-da) and
other freshwater pl ants , but they al so eat grai n ' grasses 'insects, sniils, and small invertebrates when available'
Trumpeter *unt -norma11y
consume succul ent g-reen vegetation when
available, *itt al'l paits of the aquatic plants.being utjlized
iganL; fgOOj. ponaweed (Potamogeton spp. ) tubers. ale used
.ii.'iiverv-iifooJ(iin'.netffiT).-Youngcygnets.jnthejrfirst three weercs reea primarily on anima'l matter'. "i!l-Plant life
becoming increasingly more impor_tant with age (Bank-o 19bu,'
In Soutfrcential "Aiaska, preferred foods include marestail
iHipp*il til:i, nors.iiiis (Equisetu.m spp'), sedses (9arSI .spP')'
anil buckb.Jri
- (f'r.nvunif,.t tr'iT-olTatal. '
Communi ti es ilomi nated by
these species 'aTffi-in rnosi nest sites (Hansen et al. 1971;
Campbeli, Pers. conrn.).
B. Types of Feeding Areas Used
Most feedi;;-;;tJ;s-ln shallow water areas, although immature and
adult ,*.ni miy teeo or graze to a -limited extent upon land;
iygn.tt teet io'tely in wat|r (Banko 1960). La-rge lakes..in Alaska
that lack emergeni vegetation and are therefore unsuitable for
breeding u..-o"tt.n usid by. nonbreeding swans when pondweed is
;ffi;; iHinJen et al . 197i). Generally during the'ir f.irst two
weets, yorng-.ygnltr feed il ug.. shallow waters of six inches to
one foot i; a;pih. when feedirig occurs in deeper waters,. they
guif'.. fooOstriti brought to the-surface by their parents (Banko
1e60).
REPRODUCTIVE CHARACTERISTICS
A. Reproductive Habitat
Alaska trumpeters require a minimum of 140 and up to 154 ice-free
days to .o*[i.i.-a ieproAuctive cyc'|e.. This requirement precludes
use of otnErwise snitubl e habi tit above approximatery- 2,709 ft
elevation ina Aictates that most nest'ing occirrs below 500 ft {King
1968, Hansen et al. 1971). Specific-physical features of the
trumpeter - swin breedi ng triUi tat 'i ncl ude the fol l owi ng
requi rements :o Stable-waters that possess a relatjve1y static level, not
exhibiting marked seasonal fluctuations
" Quiet iaki, marsh, or slough waters, not subiect to obvious
currents or constant wave actiono Shallow waters of lakes or open marshes that do not preclude
considerable digging and fo'raging-for lower aquatic plant
parts (roots, tqbirn etc.) (Banko .|960)
Trumpbter *.* - [,uiia their n'esls in extensive areas of marsh
ueg.liiion. The nests are bui I t d'i rect'ly ol_ !!e ta.-* bottom
i#;;; et'at. rgzii-in water 1to 3 ft delp (Be1'lrose 1e76). In
Alaska, t.dg.s and horsetails predominate where nests are found'
Trumoeter-iiint-iiso utilize mtiskrat houses and beaver lodges for
nest\ ng (Arneson, pers. comm. ) .
V.
159
B. Reproductive Seasonal itY
Molt breeding pairs are at their nest sites by early May' and the
first egg appears some time between April 28 and May 11 (Timm
1975). The first hatching dates range from June 16 to June 29(ibid.). In Alaska, cygnets are unable to fly until 13 to 15
weeks of age (Bellrose L976). After leaving the breeding areas,'larger numbers of trumpeter swans congregate on ponds and marshes
along the coast in late sunmer and ear'ly fall. Most swans depart
by mid 0ctober but some years may remain until freeze-up in
November (Timm 1975).C. Reproductive Behavior
Swlns usual]y mate for ljfe; however, if one of the pair is lost,
the other may subsequently mate again (Bel lrose 1976).
Territoria'l behavior is striking'ly evident among trumpeter swans;
a mated pair vigorously defends the mating, nesting, and cygnet
feeding grounds (Banko 1960). A pair occupies its territory_ as.
soon as there is open water in the spring, and some pairs defend
their territories until late surmer, when the cygnets are half
grown (Bel I rose 1976) .
in Alaska, Hansen et al. (1971) found on'ly one pair of territorial' trumpeters on each small water area ranging from 6 to 128 acres.
0n'ly a few 'large I akes , 1 to 4 mi 'long, were occupi ed by two or
three breeding pairs.
D. Age at Sexual MaturitY
Banko (1960) concluded that trumpeters may begin nesting as early
as their fourth year or as late as their sixth year. Perhaps the
density of territorial pairs accounts for some of the variation
(Bellrose 1976).E. Cl utch Size
From 2 to 10 eggs are 1a'id, usual'ly 5 to B (Timm 1975). In
Alaska, the c'lutch size ranges from 4.9 to 5.2 eggs but may vary
as a result of early and late springs (Tinrn 1975, Hansen et al.
1971).F. Incubation Period
The period of incubation varies from 33 to 37 days (Banko 1960,
Hansen et al. 1971).G. Rearing of Young
The female usually broods her newly hatched young on the nest for
the first 24 hour!, 'longer if the weather is inclement (Hansen et
a'l . 1971). Both parents are sol'icitous of their young; the fami]y
forms a tightly knit group, with the actively sw'immjng or feeding
young flanked by each parent (Bellrose 1976). The offspring .areusuaily left by their parents upon approach of the breeding
season, at least until their first flight'less molt in late June or
early Ju'ly (Banko 1960).
VI. FACTORS INFLUENCING POPULATIONS
A. Natural
Survival of young to the flight stage (90-100 days) is greatly
affected by -severe weather, -predator populations (coyotes and
160
B.
eaq'les) (Banko 1960), and diseases (Sarvis, pers. comm.; Banko
;figi.' ilo.t;tiri-;i Larrt trumpeter iwans is caused primarilv.bv
;;;ifr;. iireezini ot feeding areas for extended periods causing
iii.riii,in j -ina ini..q*nttv OV mamma'l'ian predation {coyotes -and;il;;- ott..tl ls;n[o -igorjj" uni iuiun predation (solden easles)
(Banko 1960).
Human-rel atedniiiuiti.r having the greatest potentia'l for causing future
;il;i;;i;; aecr ines are those that alter or eliminate swan
fiufiitut, parti.ui'u.tv nest j n_g _and mo1 t'ing areas , or that di sturb
swan use areas, such as the following:;"-' nqrutii-iuUiiiate atteration (e.g., from accelerated aufeis'
mechanical removal )o Chronic OeUi t itation due to ingestion or contact wi th
petro'leum or Petroleum Productso Chronic debii itation 'due to ingestion or contact with
chemi cal so Harassment, active (e.9., intentional hazing, chas'ing) --!o Harassment, passive (e.g., construction noiSe, veh'icle nolSe'
human scent)
' i;drruption of ongoing behavior: alarm, flighto Terrain alteration or destruction
" Vegeiation-iorpolitlon change to a 'less preferred or usable
spec i es
" Vlgetation damage/destruction due to contact with petroleum'
pelrot eum proaricts , oF chemi cal s .( I imi ted to pl ant s pe-
ties/associations important to swans)
" Vegetation'-dlmage/destruction due to hydraulic or thermal
erosion anO/or d"eiosition (limited to plant species/associa-
tions imPortant to swans)o Vegetatibn damage/destruction due to mechanical removal or
material oueiiiy (l imited to p'lant species/associations
important to swans). poison'ing dr; a; iead shot introduced in marsh habitat by
hunters (ring' Pers. comm.) -o Loss of t.iu"*fy Ou. to .staUtishment of human recreational
iitivity iniroOirced to swan nesting territorjes, including
boating- und- itoitptun. activity' clmping, and cabin sites
(ibid.)o I1 legal huntingo Water level or water
in drainage Patterns'
quality fluctuation, including .changesl'ong-tlrm increase or decrease in water
I evel so Accidents (striking power, telephone, oP fence wires
flight)
(See thJ Impacts of Land and Water Use volume of this series
iaaitionul information regarding impacts. )
in
for
161
VI I. LEGAL STATUS
In Alaska, waterfowl are managed by the U.S. Fish and l.lildlife Service
and the Alaska Department of Fish and Game. They are protected under
internationa'l treaties with Canada (Great Britain), 1916, Mexico' 1936'
Japan, 1912, and the Soviet Union, 1976.
VIII. SPECIAL CONSIDERATIONS
1.Nest disturbance. When trumpeter swan nests have been disturbed'
ffint.|yabandontheirnestsitesandsometimeswalk
overland to another lake, which makes them much more subject to
predation (Hughes, pers. conrm.). 0n the Copper River delta, pairs
of trumpeter swans with nests or young were more sensitive to
human disturbance than adults wjthout young (Timm and Sellers
1979). Also the timing of egg removal is a critical factor in
renesting (Banko .|960). Even aircraft_flying at 2000 ft can cause
trumpetei swans to abandon thei r I ake (Portner r Per! . 99m: ) .
.Moltinq and staging areas. Most nonbreeding birds in Alaska beginr ear'ly Ju'ly. Foi breed'ing pairs, males
usually molt first (Hansen et al. 1971). Birds are f'lightless for
about gO Oays (Hansen et al. .|971, Be]'lrose .|976).
Migration stops (restjng and ). Trumpeter, ^ swans
ate resting and feeding
areas is especially critical to the young, which cannot travel aS
far (Hughes, pers. comm. ).
winterinq habitat. Good swan wintering habitat usual'ly contains a
ffilevelandopenterrainallow.ingtrumpeterswansto loaf or f1y without restriction of visibility or movement. 0n
smaller streams, where air space over water is lim'ited' this
requirement becomes especia'l1y important, because tr,umpeter: ^!99dami'le unrestricted air space for take-off (Banko I 960).
Unobstructed snowfjelds or meadows adjacent to open streams 0r
ponds are regularly used for loafing sites, .especial-1y i.n 'late
wi nter, when the snbw hardens w'i th settl i ng ( i bi d. ) . 0n streams ,
water movement is important in keeping such waters open during
moderately cold weather, but some source of warm water is a
necessity during prolonged periods of co'ld weather in the winter
(ibid.).
When freshwater locations
freeze, swans are sometimes
co'ld periods (Tinrm '1975).
LIMITATIONS OF INFORMATION
Molting and brood rearing areas are not well documented. Basic
researih information has only been collected occasionally (usua'lly one
survey per year every five years) 'in the Copper River delta and Cook
Inlet- basin. ntso all wintering areas south of Alaska for Gulf Coast
trumpeters have not been found (Tinrm .|975).
along the eastern North Gulf Coast
driven to salt water during extremely
2.
3.
4.
IX.
162
REFERENCES
Arneson, P. 1984. Personal communication. Game Biologist, ADF&G, Div.
Game, Anchorage.
Banko, W.E. 1960. The trumpeter swan: its history, habits, and population
in the United States. Cited in Bellrose L976.
Bellrose, F.c. tg76. Ducks, geese, and swans of North America.
Harrisburg, PA: Stackpole Books. 540 pp.
Campbel I , B. 1984. Personal communication. Asst. Waterfow'l Biologist'
ADF&G, Div. Game, Anchorage.
Gabrielson, I.N., and F.C. Lincoln. 1959. The birds
Harrisburg, PA: The Stackpo'le Co. 922 pp-
Hansen, H.A., P.E.K. Shepherd, J. King, , and W.A. Troyer. L97I. The
trumpeter swan in A'laska. Cited in Bellrose 1976.
Hughes, J. .1985. Personal communication. Nongame Biologist' ADF&G' Div.
Game, Anchorage.
King, J.G. 1968. Trumpeter swan survey, -_Alaska. Cjted in terrestrial
habitat evaluation criteria handbook-Alaska. 1980. Div. Ecological
Services, USFWS, Anchorage' AK.
King, J.G., and B. Conant. 1980. The 1980 census of trumpeter swans on- Alaskan nest'ing habitat. USFWS, Juneau, AK.
King, J.G. 1984. Personal communication. l'lildlife Biologist' USFhlS'
Juneau, AK.
Palmer, R.S., ed. 1976. Handbook of North American birds. Vol , 2:
Waterfowl .
portner, M.F. '1985. Personal communication. hlildl ife Biologist' USFll|S'
Soldotna, AK.
Sarvis, J. 1982. Personal communication. t'|ildlife Biologist, USFblS' Cold
Bay, AK.
Spraker, T. 1984. Personal corrnunicat'ion.
Di v. Game, So]dotna.
Area Mgt. Biologist, ADF&G'
Pages 265-343 in
inventory of Prince
inventory actjvities-
t,l-17-11, Job 10.0.
of Alaska.
Tirrun, D, t975. Northeast Gu]f Coast waterfowl .
E.D. Kl inkhart, A fish and wildl ife resource
l^lilliam Sound. Vol. 1:, Wildlife. 1978.
Timm, D., and R. Sellers. 1979. Report of survey and
Waterfowl. ADF&G, Fed. Aid in hjildl. Rest. Proi.
163
Freshwate r I Anadromous Fish
Arctic Char/Dolly Varden
Life History and Habitat Requirements
Southrest and Southcentral Alasha
a
a
I.
II.
lll nnaeus I
Dolly Varden and arctic char are two
subfamily Sa'lmoninae. Because of
discussed jointly and referred to as
RANGEA. Statewide
cl ose'ly rel ated salmoni ds of thetheir similarities they will be
char.
..4@'r
Map 1. Range of arctic char (ADF&G 1978)
Common Names: Dolly Varden, arctic char
Scientific Names: Salve'linus lq]rnq (Walbaum), Salvel inus alpinus
Anadromous and nonanadromous populations are found from the arctic
coast south along the western, southwestern, southcentral, and
southeastern coastal areas of Alaska. Isolated populations of
resident (landlocked) char are found in lakes and streams
I lg n,,n t ry1 I I r r rr rRnmrr*#slfl
t67
scattered throughout Interior and Arctic Alaska and on the Kenai
Peninsu'la and foOiat< Island (ADF&G 1978, Morrow 1980).
B. Regional Distribution SurmarY
To-supplement the distribut'ion information presented in the text,
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale,
bul some are at 1:1,000,000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition,
a set of colored 1:1,000,000-sca1e index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.
1. Southwest. Char are widely di stri buted throughout most
s@s in the Southwest Region. Important drainages . of
gi'i stol Bay i ncl ude the Tog'iak Ri ver, the Wood Ri ver Lakes
system, the Ti kchi k-Nushagak system, the I'l i amna-Kvi chak
system, the Naknek River and Lake, and the Becharof and
Ulashik rivers. Some important lake-river systems_ in the
xooiat< region inc'lude uganik, Ljttle River, Karluk, Ayakulik
(neA Rivei), Akalura, Saltery, Buskin, and Bara.bara Iakes.
ihar are also abundant in the Aleutian Islands (ADF&G L976,
1977a and 1977b). (For more detailed narrative informat'ion,
see volume 1 of the Alaska Habitat Management Guide for the
Southwest Region. )2. Southcentral. Char are widely distributed throughout the
So{Th'cenfraT area. Char are found in the Klutina River and
Tonsina River drainages and small tributary streams to the
Copper River (Wi t t iams, pers. conrm. ). In the Prince hli l l iam
Soirha area, nearly a1 1 freshwater systems , w'ith the possi b1e
exception of short g'lacial streams on the southeast side of
the Kenai Peninsula, contain char. Char are found in lakes
and streams on the Kenai Penjnsu]a, most notably the Kenai
River, Kasjlof River, Deep Creek, Stariski Creek, Anchor
River, and lakes in the Swanson River drainages. char are
also found in many streams draining into the west side of
Cook Inlet and in the Susjtna Rivei drainage (ADF&G 1978).
(For more detailed narrative information, see volume 2 of the
Alaska Habitat Management Guide for the Southcentral Region.)
III. PHYSICAL HABITAT REQUIREMENTSA. Aquatic
Char are found in clear and glacia'l
del tas and 'lagoons (ADF&G L977 a) ,
(Morrow 1980).
rivers and lakes, brackish
and nearshore marine waters
1. Water qual ity:a. Temperature. Recorded water temperatures during the
spai^rnfig- period range from 3 to nearly 13'C ('ibi d. ) 'although char have been observed spawning in-tempera-
tures as low as 0.5'C (Moore 1975). In Southeast
Alaska, spawning occurs when water temperatures are 5.5
168
b.
to 6.50C (Morrow 1980). Egg-hatching and a.levi.n devel-
;;t;;i i s' qul te sl ow but -does
.aPpear to b.e dependent
uoon temDerature, with warmer-than-normal temperatures
i[i.f.*itng hatth'ing and resul!i19-.in. ear]ier-than-
normal fry'emergence] Blackett (1968) _determined that
louineast"Alaskianadromous char eggs held in a hatchery
uegan hatching after 129 days in water with a tempera-
lui. .unge of-8.3 to 0.6"C. No upper or lower tempera-
ir.. tofd.unc. limits of char eggs or alevins were found
in the literature; however, egg; are frequently exposed
to temperatures from 0.0 to 2.2:C duping incubation, and
Scott irnd Crossman (1973) report s'ignif ican_t egg mortal -
liV ut temperaturei above 7.8oC. Juveni'le char have
beLn observed burrowing into the substrate when water
l.*p..-Jiui"t decieaied io 2"C (Elliott and Reed 1974).
imi!rat.ion of char from overwintering areas to summer
feedinq areas usually occurs after ice break{P. jn lakes
ii-iuoit-o;f (Armstr6ng 1965, ADF&G 1977b). Fish reduce
i..Aing and seek overwintering areas when temperatures
decrease to o.'t.t;; 5'C (frieger 1981, ADF&G 1977b).
Vertical distribution 'in lakes appears to be
temperature-dependent, with char preferring..mid water
ina' Uottor Oeiths witfr temperatures lower than 12.8"C
(ADF&G 1e76).
oissolved oxyqen (D.0.). No information was found in
Tffi influence of dissolved ox'gen
levels on the survival and development of char; however,
inferences can be made from work on other salmonid
ip.ii;;:- Sufficient transport of D.0. to, and metabol'ic
wastes f rom, devel op'ing egjgs and al ev'ins by- i ntragra.vel
iiil-l s cruli at
' ioi su"rvi"vil of eggs and al ev'ins- (Vaux
Lg6i, Wickett 1958). Relatively -Iow intragravel D.0.
ieu.is during the egg-development stage may increase egg
mortality, inttuence the rate pl.egg. development' or
".Ari. th'e f i tness of al ev j ns (Al deid j ce et al . 1958 'Silver et al. 1963).
Turbiditv. Little'work has focused on the influence of
ffiffi on the survival and development of char;
no*auaar- inferences can be made from work on other
iiironi d species. Deposi tion of fj ne sediments i n
spawning areas could reduce the water interchangt l:l lil:
rbaa ani retard or prevent the emergence of fry (Koski
fg66l. Accumulatioh of organ'ic debris can reduce
OiiioiveO oxygen below safe-levels through oxidation
(Reiser and BJbrnn 1979).ialinity. PhVsio'logicai changes for sa'l'inity to1erance
of anadromous char irobably beg'in before emigration from
freshwater overwintering ireai to marine summer feeding
;;;;; lc;ntl ina wasnei 1e65, Johnson 1e80)' Roberts
(tgii), who conducte-d experiments with a nonanadromous
c.
d.
169
population of char that had been iso1ated from sea water
for about 12,000 years, concluded that nonanadromous
char retain a certain degree of salinity tolerance.
2. Water quant'ity. sufficient water velocity and depth_ ale
requm-l'|owadequatewaterflowduringe99andalevin
deve'lopment. Low f I ows and co1 d wi nter temperatures coul d
cause redds to desiccate or freeze (Krueger 1981). Excessive
velocities or flooding can cause egg dislodgement and/or
displacement of juvenile (presmolt) char from rearing areas
as we1l as hinder upstream fish migration (ibid.). Juvenile
char in the Terror River on Kodiak Island are associated with
relatively slow current velocities in poo1s, quiet side
channels, and sloughs and tributaries (Wilson et al. f981).
Char have been obierved spawning in water depths of 0.2 to
4.5 m (Krueger 1981, ADF&G L977b) and in moderate current
velocities ringing fiom 0.3 to 1.2 m/sec (1.0 to 3.8 ftlsec)
(Blackett 1968; Scott and Crossman 1973).
3. Substrate Preferred spawning substrate is small-to-coarse
fwalffilze) gravel (Scott and Crossman 1973, McPhai I and
tindsey 1970).- Blackett (1968) found char in Southeast
A'laska- spawni ng primari 1y i n sma'l I grave'ls , 6 to 50 mm i n
diameter. Wilion et al. (1981) found char on Kodjak Island
spawning on gravels ranging from 2 to 3? mm in diameter.
A grave'l layer over fertilized eggs in the redd protects eggs
from sun'light and predation and reduces disturbance by_ ice
and floodi (Krueger 1981). Lakes, deep pools in'large
rivers, and spring areas provide critical freshwater
overwintering habitat (ADF&G 1,977a). Juvenile char burrow
into substrale interstices and logging debrjs and slash to
avoid cooling water temperatures (Elliott and Reed 1974).
B. Terrestrial
Rocks, logs, root balls, and undercut stream banks in.poo1s, quiet
side chan-nals, and high-water overflow areas provide cover for
young-of-the-year fish, Char seldom swim near the water surface,
freferring to remain near the bottom (Krueger 1-981' ADF&G I977b,
AOfaO L9i7a). 0lder char prefer deeper and faster water that
affords greater cover.
IV. NUTRITIONAL REQUIREMENTSA. Preferred Foods
Fry begi n acti ve feedi ng as soon as they em_erge. J.uven'i I es feed
on var-ious winged inseits, 'larvae of mayff ies and midges' a!d
various small c-rustaceans (Karzanovskii 1962, Krueger 1981). In
the Bristol Bay dra'inages, fish (sticklebacks, sculpins,. black-
fish, and salrion fry)l fish eg9s, and invertebrates (snails,
leeches, c'lams, insecis, and insect larvae) are major food sources
(A'lt 1977, Moriarity 1977, Greenback 1967).
Russell (1980) found that char in the Lake Clark area of Bristol
Bay consumed gastropods, pe'lycopods, caddig fly (Trichoptera)
I aivae and aaril ts , 'ants and
-
smal 1 wasps ( Hymenoptera ) , mi dge
170
B.
(chironomidae) pupae__and adults, adult . aquatic beetles (col-
;;;i;;;i, -;;il' smatt crustaceans (amphipods, copepodsr drd
cl adocerans ) .
In the wood River Lakes system, char feed on sockeye.salmon:I9lt
;;ri;; t[!- smot t' s-iummei mi griti on to Nushagak Bav .
(Rogers 1:9.72 'B;kji; 1g1gl. Alaska Department of Fish and Game investigat'ions
have .indicated that char captured during this migrg!.ion contained
un'iu..uge of B.O *.f,.Ve sniolts in their stomachs (Howe 1981)'
plrili;;il- iigzii ;;;ei;J ih. food habjts or anadromous char in
lakes on Amchiita tstana. He found that in lakes with firm
bottoms adiacenC [o shore and with access to the sea' crustaceans'
followed by aquatic insects, were the major foods; whereas in
I akes wi th tuaAi bottoms, aquat-i.c j nsects ' fol.1o-wed by
crustaceans, "...-tn. maior ioods. Ctrar in landlocked lakes on
A*;[iik; iei prima.ity on-aquatic insects, f_ish, and fish eggs.
In marine wateril 's"*.ii, herping, iuveni.le salmon, sandlance'
g...nj i ng-, .trf'pi'nr , Jf orna.t I ivae-, and c9d are major food
components. [t;i;pods,- decapods, mysids' euphausi'ids'
brachi opods , porvi['i;i;; ,' and _i soliods are al-sq i ncl uded i n thei r
diet (Armstrong ina No.io" 1980-,-'Jofrnson 1-98.0). Townsend (1942)
found that char *blr.Lo n.ui the shumagin l-s].ands contained 'large
numbers of flounO.. juveniles and larvie of the sand lance' gff
Amchitka IstanO,'cfrar" ied on a variely ql_items, mainly amph'ipods'
rnviioi, und smail fish (Neuhold et al ' 1974)'
Feed'ing Locati ons
JuveniIes feed primarily from .the benthos in Iow velocjty, areas
along stream uni lui. mirgins (Armstrong a.nd Morrow 1980, Johnson
i980j.- 0ia.r .tru.-rou. t-o deeper and faster..stream reaches with
hi;h.; densitiei- of drifting invertebrates (K:y:g^t:^1981'
^AD|&GLg77b, ADF&G 1y1il il . Adul t inadromous char appear to be . equal 'ly
;;;;[i. ot-iutiing iooo from mid water or from'the bottom (Johnson
i960):- nesioent'ctrii in lakes feed-primarily.on the lake bottom
(Murray, pers. ;;;:) . mcpiige ( 1e7i) esti.mated that 40% of the
inur piriufation -in ilie Wood R'iver Lakes system feed at in.lets and
outlets of lakes or confluences of rivers and streams during
;;;k;t; imot t '-n'i g.uti ont . l4orrow ( 1980.) states that adul t
anadromous char lo'itrt. the maiority of'their.annual djet of small
fish and invertebrates 'in nearshore marine waters.
Factors Ljmiting Availability of Food
No information-"us found ii the literature; however, 'inferences
can be made from work on other salmonid spec-ies. Excessive
sedimentatlon miy inniUit production of aquatic plants and inver-
tebrate fauna (Huff and McKay 1983) and reduc.e visual references'
While in tresnwaler, the chir may compete--d.irectly for food and
lpu.. wi th such f i shes as grayl i qg-,- wh'itef i sh , scul pi ns , sal mons ';il-;r;ii (n*rtrong and M-oriow igAO). . Competitive interactions
between char and coho salmon iuveniles have'been well documented
in southeastern Alaska streami (Armstrong 1970, Armstrong and
iiloi|g1if.- corp.ii*on for fooi or spac! with other species is
c.
171
V.
probab'ly negligible in lakes during the winter (Armstrong and
Morrovr 1980).D. Feeding Behavior
Char aie carnivorous but have a varied diet, dependent on the size
and age of the fish, location, and available food sources. Char
may biowse along the substrate or consume drifting invertebrates
(Aimstrong and Elliott 1972). Activity 'levels and digestive rates
drop when freshwater temperatures decrease to or bel ow 5oC
(Krueger 1981, ADF&G I977b). Mature spawners of _anadromouspopu'lations feed little, if at all, when wintering. in f_resh water
iMorrow 1980) . When 'leavi ng I akes i n spri ng and .ea11y summer,
char also appear to feed very little (Armstrong 1965).
REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat
Spawning site selection js influenced by current velocity, water
dbpthr drd substrate compositjon. Spawning sites -arq usua'l1y
located in a fair'ly strong cument near the center of the stream
in riffles or spring areas at least 0.3 m deep or in grave'l-bot-' tomed lakes (Krueger 1981, ADF&G L977a).B. Reproductive Seasonal ity
Al i races spau,n between the end of July and the begi nni n.g of
December (Meacham !977, Alt 1977). The peak of spawning activity
in Southeast Alaska occurs between September and November
(Btackett 1968, Blackett and Armstrong 1965).
Char have been observed spawning in the Terror and Kizhuyak rivers
on Kodiak Island between late August and the end of September
(wi'lson et al. 1981). 0n Amchjtka Island, Neuhold et al. (t974)
observed char spawning from mid October to late November. Char in
the Wood River Lakes system spawn in September and 0ctober
(McBride 1980). Char in the Susitna River drainage a'lso spawn in
September and 0ctober (ADF&G 1981), and spavning peaks in the
Anthor River on the Kenai Peninsula in mid October (Hammarstrom
and Wallis 1981), and in Valdez area streams in 0ctober and
November (Dames and Moore 1979).C. Reproductive Behavior
Spiwning behav'ior is similar to that of salmon. Fish are usually
piired.- The male usually takes no part in the nest-building and
lpends his time defending the redd from other male s-pawners. The
fbmale excavates the redd, often in typical salmonid fashion by
turning on her side and thrashing the substrate with her tail.
When tie female is ready to deposit her €99S, the pair descend
into the redd and press against each other latera'l1y; sperm and
eggs are released simultaneously into the redd. After completion
of-the spawning act, the female may move to the upst_ream end of
the redd and repeat the digging process, washing gravel downstream
over the fertilized eggs. The spawning act may be repeated -up to
f ive times; severa'l days are usua'l1y requi red fgr a femal e to
deposit all her eggs (Morrow 1980). Morrow (1980) described the
redds as varying from a deep pit to a clean spot on large stones.
t72
D.
The djmensions of the redd vary with the size of the female, the
trUtirit., and the current velocities. Male spawners 1a-y mate
with more than one female; occasionally a female wil'l mate
lril.tiively with two or more males {Fabricus 1953, Fabricus and
Gustafson tbS4, Krueger 1981, ADF&G L977a).
Age at Sexual Maturity !.- ^ .,..^., -^r..-.Char are un .sp.iia11y slow-grow1ng fish and attain sexual maturi-
iV-at different -ages" and sjies, iarying. with- their life history
i"na iocat environ"mental conditlons.- Three life forms of char
occur in Alaska: resident lake char, resident stream char, and
anadromous char. In general, resident stream char do not grgw as
i;;4. ;; resident lakd or anadromous stream char. Resident stream
.tui-.o*only ociur in dwarf form (t.lyg]]y TllYre and fullv 9!9wn
but only 6 to 8-inches in length) (ADF&G 1977a, Rus-sell 1980)'
e-nerat iy, norttrern populationi . grow slower,., l ive 'longgr,. and
reiif' a"imaller-maximum size thin more south-er1y populations.
Char populatjons in tfre south also attain sexual maturity.earlier
iiriirrfi*"ig8dj. mules may mature before females. In Kuskokwim Bav
i.iinug.s, char glneral'ly mature at 7 to 10 years (A1t 1-977). - In
the It iamna ryri*,- N.tiker (1967)_ found mature. char (l ife. fgrm
ilkrili ;; til;a ;t four years old. Russell (1e80) noted that
inar in the iafe ttark area- apparent'ly become mature at six years
of aqe. Most char in Southeast ntaska reach maturity by age four
or fj"ve (Blackett and Armstrong 1965)-
in. tongevity oi-cnai is va.ia5te. ghar have been found as old as
i+-v.uri-(Gr"aing.. igsg), but most'in Southeast Alaska live 8 to
ii i;;"; in.tit.ons 1e6i,-Heiser 1966, ADF&G 1978)'
Fecundi ty
ffre iecrindity of char varies by stock, location,.and size of
female. Eggi of anadromous stocfts are much larger than those of
noninaarom6ris fish and increase in size with fish age and _length
igiili.tt 1968, Morrow 1980). In Alaska, the number of eggs
gen;rafly range! from 600 to 8.,000. per female-JAff&e 1978'-Morrow
iggO, l,tclfrail-and Lindsey 1970), though Russe-ll (pe!!. cgnJm. ) has
oUseivea dwarf, prespawning females with as few as 20 mature eggs
in the Tazimina Lakes in Southwest Alaska.
Frequency of Breeding
Th;Jgh i6ur do sufier a high post-spawnjng mortality ra!!-, a
number ljve to spawn lgain iri suLsequent yeais. Armstrong (1974)
found that in a-'Southeist Alaska pobulatfon of char, 73% spawned
oni., 26% twice, and L% three timei. Up to 50% of the females
rpirti ng tor th; f i rst time survi ved to spawn ag-ai n. l'lal es are
much less flkeil to-iurvive spawning than females. Some char
Spawn in consecirtive years; others spawn at two or three-year
intervals. Most anadromous char in northern Alaska spawn only
eue"V iecond year. Freshwater char, in contrast to the anadromous
ifi;", ;i;;;i ii*uyt spawn annually (Armstrong and Morrow 1980).
G. Incubation Period/Emergence
The time of devel'opmenl varies wide'ly with temperatur.e and stock.
fmUryo aevelopment is slow in cold water temperatures. Eggs
E.
F.
173
incubate over winter, generally four to five months; however,
periods of up to eight months have been documented on the North
btope of the Brooki Range (ADF&G I977a, Yoshihara 1973). .Eggshatth as 15-to-20-mm-1ong alevins (yolk sac fry) in March or
Appi1. Alevins remain in the gravel for approximately 18 days
while absorbinq their yo'lk sac before they emerge as free-swimming
fry (20 to 25 mm) in April, May, or June (ADF&G I9_77a). In Valdez
area streams, fry emerge from the gravel in April and May (Dames
and Moore 1979).
VI. MOVEMENTS ASSOCIATED t,lITH LIFE FUNCTIONS
A. Size of Use AreasLittle information was found in the'literature on the size of use
areas required by char. Armstrong and E'lliott (tSlZ1 concluded
that seaional distribution of presmo'lt char was influenced by
fluctuating flows and water temperatures. Upper-stream reaches,
where watei temperatures are consistently warmer in the winter,
attract overwintering presmolt char.8.. Timing of Movements and Use of Areas
Resident lake char move into streams for short periods of time.
Studies in the Wood Ri ver Lakes system show that di screte
subpopulations of resident lake char concentrate at inlets and
outiets of the lakes during early summer to feed on outmigrating
sockeye smo'lt (McBride 1979). During late summer, char move to
deeper 'lake waters, probably in response to a decl ining
avajlability of sockeye smolt and to escape warming surface waters
(Nelson 1966). Mature spawners usually move back to the lake
margins to spawn 'in the fall.Litile is known about the life h'istory of resident stream char.
They are common in headwater streams during spring' surnmer, and
fali and may move into lakes for short periods of time, but they
also use lower reaches of streams. Overwintering occurs in deep
pools of streams and rivers (Morrow 1980). Char in the Sus'itna
iljver are thought to feed in the upper reaches of tributaries
until fall and lhen m'igrate to the main stem to overwinter (Sundet
and Wenger 1984).
Juvenile anadromous char rear in streams and lakes for two to
seven years before outmigrating as smolt (ADF&G t977a, ADF&G
I977b).- Most immature and mature char emigrate from overwintering
areas to mari ne suntmer feed'ing areas fo1 1ow'ing i ce breakup f rom
April to June. The char smolt migration'in the Anchor River on
the Kenai Peninsula takes p]ace in late May and early June
(Harnmarstrom and Wallis 1983). Nonlake systems may support_an
additional autumn smolt outmigration (Armstrong 1965 and 1970,
Armstrong and Kissner 1969, Dinneford and Elliott 1975 and Elliott
and Dinneford 1976).
Individua'ls remain at sea feeding in the estuary and a'long tfe
coast for a period of a few weeks to seven months (Morrow 1980).
While in the marine envjronment, char stay in coastal areas near
the estuary and do not usually migrate distances greater than 100
174
mi (ADF&G 1977a, ADF&G Lg77b). char begin reentering fresh water
in July ina-ruy'continu"-th.bugh December, with spawn_ers entering
f .irst, fol I owed by imrnalure ii"sf' and nonipawnets (ADF&G t977a) '
Both spawning and
-nonspawning.
9[ar. return to their natal stream or
lake to spawn o. ou."*inl"t "(N.g.jde 1979). In.the Chignik River
system-on'-ifr" Alaska peninsuta, char migrate- to. :eq from April
through June and return-io Ctrig;lik Lake ind Black Lake from late
July through September to spawn uld overwinter (Roos 1959) '
rmigraiion-"ot ipiwnea-out char to the sea or to overw'intering
areas usually occurs within tWo weeks after completion. of
spawning,-i,pl.uiiV Juring late gctober and November' Immature
charmovetooverw]nteringareas-earlier'ir]jnalilyin.ll]{'
August, and September igiuc[.ti and Armstrong 1965, Krueger 1981)'
Adutt ir'i.-uiuil1y remiin-in fresh water ttrrough the wjnter months
to avoid the cooler water temperatures of the marine environment
(ADF&G
'igzlul.--bverw'inlering iites incl ude deep lakes, deep river
poo1s, and groundwater spring areas'
VII. FACTORS INFLUENCING POPULATIONS
A. Natural
Naturai mortal ity is 'largely a res_ult of I jmited winter habitat.
Char that hatch in irtii.i runoff streams must find suitable
overwinte.ing ur.us with open water.. studies in southeast Alaska
inoicaiei ir,it-popurations'of iuvenile char suffered 51% mortal'ity
in small surface-water streams, versus about 3l% mortal'ity in
springifea-streims, from November to June (Elliott and Hubartt
Ig77).Severestreamflood.ingcqnharmdeve]oping-e.g.gs3nd
embryos and hi ndelpttt.ut f i in mi grati on (Krueger 1981) ' Low
flows and cold winter temperatures could cause redds to dessicate
or to i...i..- oepositjon'of fjne sediments in the spawning area
couldretardo.p..u.ntfryfrom_emergi.ng..(ibi.d.)..pepolitionoffine sediments in streims"with limit6d -flushing abilities could
imbed the substrate rui..iai ino significantly_reduce the avail-
aute overwinterlng f'a'Uiiit
-for juven-ile char (giorn et al . L977 '
Krueger 1981). postspawning morial_ita is, high and may account for
the riit,].ii'-removal'- ot rp to 50i", of a spawn'ing- population
(Armstrong and Kissner-1969; ADF&G 1977a). Lake-dwelling popul.a-
tions are often neav'ilV pirasitized with nematodes and cestodes
(nuiietf , pers. comm. ) " Tirere i.s- ng.significant natural predation
on chir 6xlept for cariniUallsm (Scott aid Crossman 1973, Armstrong
and Morrow 1980).B. Human-rel atedA ,rrriw'-of possible 'impacts from human-related act'ivities
in"uiii.lli,iltl?1Hi..red water temperatures, pH, dissolved
oxygen, and chemical comPosition. Ai"t;iuiion of preferred water velocity and deptho Alteration of preferred stream morphology: il:i:li: ll :5ffi:li:.?ifl':l: il.il11?il"l'lEil'3lo,,,tv or
t75
substrateo Reduction in food suPPlYo Reduction in protective cover (e.9., overhanging stream banks
or vegetation)" Shock waves in aquatic environmento Human harvest
(See the Impacts of Land and Water Use volume of this series for
addjtional information regarding impacts.)
VIII. LEGAL STATUSA. Managerial Authority
The Alaska Department of Fish and Game, Division of Sport Fish,
has managerial authority over char.
IX. LIMITATIONS OF INFORMATION
Most life history information on char pertains to the sea-run variety.
Ljttle is known about the habits of nonmigratory char. There is very
little data relating the various char life stages to the physica'l and
chemical characteristics of their habitats.
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176
. 1965. Some migratory habits of the anadromous Dol1y Varden
-
saT;el inus
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TttrZfi-
. 1970. Age, food and migrat'ion -of Do11y -Varden smolts in
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Blackett, R.F. 1968. Spawning behavior and gatly l.jfe. history of
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Alaska. ADF&G, Res. RePt. 6:1-85
Blackett R., and R. Armstrong. 1965. Investigations of-anadromous Do11y
Varden popul ati ons i n lfre Lake Eva-Hanus Bay _drai nages , Southeast
Alaska.'AOfaO, Fed. Aid in Fish Rest. Job comp'letion rept. Vol. 6.
Proi. F-5-R-6, Job 2-8.
Buklis, L.S. Ig7g. Effects of confinement on arctic char in the Wood River
takes system, A]aska. ADF&G, Informational Leaflet No. 182. 61 pp'
Conte, F. n and H. Wagner. 1965. Development of osmotic and ionjc
regu'lition in juvinile steelhead trotit, salmo gairdneri. Comp.
Biochem. Physiol. 14:603-620.
Dames and Moore Consulting Engineers. 1979. Freshwater aquatic habitats of
the Vatdez
-;;;;. - Piges- 263-288 in United States Environmental Pro-
i.ition Agency, enviionmental imfldt statement, Alas!a_ petrochemica'l
facil ity, Gtfez, Alaska. Appendix, Vo1 . 1, EPA 910/9'79'064. 584 pp.
'ln
in
177
Dinneford, W.B., and S.T. Elliott. 1975. A study of land-use activities
and their ielationship to the sport fish resources in Alaska. ADF&G'
Fed. Aid in Fish Rest. Ann. performance rept. Vol. 16. Proi. F'9-7,
Job D-I-B.
Elliott, S.T., and l,l.B. Dinneford. 1976. A study of land-use activities
and their relationship to the sport fish resources in Alaska. ADF&G,
Fed. Aid in Fish Rest. Ann. performance rept. Vol. 17. Proi. F-9-8'
Job D-I-8.
Elliott, S.T., and D. Hubartt. 1977. A study of land use activities and
their reiationship to sport fish resources in Alaska. ADF&G, Fed. Aid
in Fish Rest. Ann. performance rept. Vo'|. 18. Study D-I-B.
Elliott, S.T., and R.D. Reed. I974. A study of land-use activities and
their reiationsh'ip to the sport fish resources in Alaska: ecology of
rearing fish. ADF&G, Fed. Aid in Fish Rest. Ann. performance rept.
Vol. 15. Proi. F-9-6, Job D-I-8.
Fabrjcius, E. 1953. Aquarium observations on the spawning behavior of the
char, salmo apl inus. Rept. _Inst. Freshwater Res. Drottningholm
35:51-571. Cited in Morrow 1980.
Fabricus, E., and K.J. Gustafson. 1954. Further aquarium observations on
the-spawning behavior of the char, salnlo alpinu.s. L. Rept. Inst.
Freshwater R-es. Drottningholm 35:58-104. Citea'in Morrow 1980.
Grai nger, E. H. 1953. 0n the age , growth, mi grati on , - productj ve- potenti al 'ind
-
feedi ng hab'i ts of ine -arcti c char (sal vel i nus gl=Pilgl of
Frosbisher day, Baffjn Island. J. Fish Res. Bd. Ca-n. mf6):326:370.
Greenback, J. 1967. Sport fish survey, Katmai National Monument, Alaska.
NMFS: Auke Bay Biolog'ical Laboratories Manuscript Rept. 35. 30 pp.
Hall, J.E., and D. McKay. 1983. The effects of sedimentation on salmonids
and macro-invertebiates - a literature review. ADF&G, Div. Habitat'
Anchorage. 31 PP.
Hammarstrom, S., and J. Wall is. 1981. Inventory and cat-a-1-o-gin! .of -[qn?i
Pen'insula and Cook Inlet drainages and fish stocks. ADF&G, Fed. Aid in
Fjsh Rest. Ann. performance rept. Vol . 22. Proj. F-9-13, Job G-l-C.
. 1983. Inventory and cataloging of Kenai Peninsula and Cook Inlet
---rainages and fish stbcks. ADF&G; Fed. Aid in Fish Rest. Ann. perfor-
mance iept. Vol. 24. Proi. F-9-15, Job G-l-C.
Heiser, D. 1966. Age and growth of anadromous - Po] lV. Varden char,
silvelinus malma (Walbaum),- in Eva Creek, Baranof Island, Southeastern
Tfask-d.-TDFEGIResearch Rept . 5 z l-29 .
178
Howe, A.L. 1981. [Memo-.to M' Kaill]'
Anchorage. 3 PP. + figures'
Johnson, L. 1980. The arct'ic char, SalvelinYs aplinus' Page-s. 15-98 in
E.K. Balon, €d. Chars: salmonid fiThf-ot-tne ge-ntls Salvelinus-. The
[iug., the
-Neiherl ands: Dr. W. Junk by Publ'ishers. 928 pp'
Karzanovsk'ii , M.Y. Lg62. Food of migrating fr1 o!
-Qnc-ofhvnchgs,
gorbgigla
and Sal vel inrr - mq-lrna i n the ri verl of SakhET-i n ' Ryhoe Khoz '
ie(o):24-25
Koski, K. 1966. The survival of coho salmon (0ncorhJn-c!.U-s. kisglch) from egg
deposition to emergence 'in. tfiree 0regon coasftT-Sfearns. X"S' Thesis'
Orbgon State Univ., Corvalis' 84 pp'
Krueger, S.W. 1981. Freshwater habitat relationships: Do]1y varden char
(Satvettnrr-"rii*ui (WiiUaum). ADF&G, Div. Habitat, Resource Assessment
Branch. 38 PP.
McBride, D.N. Ig7g. Homing of arct'ic cfrarr. sa.lv-e] jn-us. 9Jj!u (Linnaeus)'
to feeding and spawning siies in the i^,ood--RTFla-6Tstem, Alaska'
M.S. Thesir, uniu. Alas-ka, Southeastern senior college, Juneau'
. 19g0. Homing of Arctic char, lalYelinus lpl-inu: (Linnaeus) to
-f_eding
-ina spawning ti!; in
- il.' wooa'-TTver Gk-Tvstem' Alaska'
noFAe,-Informaiionat
-Leaflet No. 184' 23 pp'
McPhail, J.D., and c.c. Lindsey. .1970. rrtl*ater fishes of northwestern
Canada ana Rtaska. Bull. Fisfr. Res. Bd. Can. 173:381 pp.
Meacham, C.P. 1977. Arctic char- predations assessment and control
jnvestigationi within the Wood River -System, Alaska, 1975 and L976'
Bristol Aay-bita nept. f'fo. 75. ADF&G, Div. Conrner. Fish, Anchorage'
Metsker, H. 1967. Iliamna Lake watershed freshwater commercial fi'sherjs
invest.igation of 1g64. ADF&G, Div. commer. Fish. Informational Leaflet
No. 95. 50 PP.
Moore , J . W. 1975 . Reproduct'i ve bi ol Og-y of anadromous Arcti c char '
Sal vet i n* Tipinur
'ii. i,l; the cumbeit and south area of Baff j n Isl and.
ffi):143-151.
Moriarity, D.ltJ. 1977. Arctic char in the wood River Lakes. Final report
to Al aska Oepartmeni of Fi sh and Game fgf peri od J'{.ovemb.er 1 , 1975 to
0ctober Sf, -igZO. Univ. 1,.1ishington, Co'l1ele of Fjsheries, Fjsheries
Research Institute.
Morrow, J.E. 1980. The freshwater fishes of Alaska. Anchorage, AK: Alaska
Northwest Publishing Company. 248 pp'
Located at: ADF&G, Div. FRED'
179
Murray, J.B. 1984. Personal communications. Area Mgt. Biologist, ADF&G,
Di v. Sport Fi sh , Kodi ak.
Nelson, M.0. 1966. Food and distribution of arctic char in Lake Aleknagik,
Alaska during the summer of 1962. M.S. Thesis, Univ. Washington.
164 pp. Cited in Moriarty 1977.
Neuhold, J.M., W.T. He1m, and R.A. Va'ldez. I974. Amchitka Bioenvironmental
Program: freshwater vertebrate and invertebnate eco'logy of AmchitkaIsland. Battel le Memorial Institute, Columbus Laboratories, USAEC
Rept. BMI-171-154. 37 pp. Cited in Armstrong and Morrow 1980.
Palmisano, J.F. 1971. Freshwater food habits of Salvelinus malma (Wa]baum)
on Amchitka Island, Alaska. M.S. Thesis, TfEh-Fate--Ilfrf-v., Logan.
76 pp. Cited in Armstrong and Morrow 1980.
Reiser, D., and T. Bjornn. I979. Habitat requirements of anadromous
salmonids: influence of forest and rangeland management on anadromousfish habitat in the western United States and Canada. USDA Forest
Service, Gen. Tech. Rept. PNW-96. Pacific Northwest Forest and Range
Experimental Stat'ion, Portland,0R. 54 pp.
Roberts, R.A. 1971. Prelimajnary observat'ions on the ionic regulations of
the Arctic char Salvelinus alpinus. J. Exp. Biol. 55:213-222. Cited
'in Johnson 1980
Rogers, D.E. 1972. Predator-prey relationship between Arctic char and
sockeye salmon smolts at the Agulowak River, Lake Aleknagik, in L97L.
Fisheries Research Institute, Univ. Washington. Circular No. 72-7.
Roos , J. F. 1959. Feedi ng habi ts of the Do1 1y Varden, Sal vel i nus malma
(Walbaum), at Chignik, Alaska. Trans. Am. Fish. Soc. 88:253-260.
Russell, R. 1980. A fisherjes inventory of waters 'in the Lake Clark
National Monument Area. ADF&G, Div. Sport Fish' and USDI: NPS.
197 PP.
. 1983. Personal communications. Asst. Area Mgt. Biologist,
-T-D-F&G,
Di v. Commer. Fi sh . , Ki ng Sal mon.
Scott, W.B., and E.J. Crossman. 1973. Freshwater fishes of Canada. Bull.
Fish. Res. Bd. Can. 184:965 pp.
Silver, S., C. Warren, and P. Doudoroff. 1963. Dissolved oxygen
requirements of developing steelhead trout and chinook salmon embryos
at different water velocities. Trans. Am. Fish. Soc. 92(4):327-343.
Sundet, R.1., and M.N. Wenger. 1984. Resident fish distribution and
population dynamics in the Susitna River below Devil Canyon. Part 5 in
D.C. Schmidt, S.S. Ha1e, D.L. Crawford, and P.M. Suchanek, eds. ADFm
180
Sus'itna Hydro Aquatic Studies. nepl. 2z Resident and iuvenile
anadromout fiin investigations (May-0ctober 1983).
Townsend, L.D. Ig42. The occurrance of flounder post-larvae i.n fish
stomachs. cJp.i a tgqi:.iio-izt. cited in Armstrong and Morrow 1980.
Vaux, W.A. 1962. Interchange of stream and 'intragravel^water in a salmon'--"'tpi*ning riffle. USFWS-, Spec. Sci. Rept. Fish No. 405. 11 pp.
l^lickett, W. 1958. Review of
product'ion of Pi nk and
15(5):1,103-1 ,126.
certain environmental factors affecting -the- chum salmon. J. Fish. Res. Bd' Can'
Will.iams, F.T. .19g4. personal communication. Area Mgt. Biologist, ADF&G'
Di v . SPort Fi sh , G'lennal I en .
tr,lilson, tr|. , E. Trihey, J. Baldrige-, C. Evans, J. Thiele, and D' Trudgen'
19g1. An assessment of en-vironmental effects of construction and
operation oi-ln.-pioposeo itrro. Lake hydroelectric fac'ility' Kodiak,
Alaska. Instream flow stuOiei final report. Arctic Environmental
Information and Data center. univ. Alaska' Anchorage. 419 pp'
Yoshihara, H.T. Ig73. Monitoring and evaluation of arctjc waters with
emphasis on tie'fltrth Slope diainages. ADF&G, Fed. Aid in Fish Rest'
Anh. prog. rept. Vol. 13.' Proj' F-9-5, Job G-III-A'
181
I.
II.
Arctic Grayling Life History and Habitat Requirements
Southwest and Southcentral Alasha
a
a
.'.4!kD'
Map 1. Range of arctic grayling (ADF&G 1978)
NAMEA. Engf i sh Name: Arcti c graYl i ng
B. Scientific Name: tnymallus aicticus (Pallas)
RANGEA. Statewide
Native arctic grayling are distributed throughout tls I.nterior and
Arctic regions"oi Alaika as well as in Southwest Alaska north of
Port Heid-en and west of the A]eutian Range. stoc.kjng programs
hive pioduced self-sustaining populations in Southeast Alaska,
Prince hliliiam Sound, the funii'Peninsula, and Kodiak Is'land
(ADF&G 1978).
e\
183
B. Regiona'l Distribution Surmary
To-supplement the distribution information presented in the text,
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale,
bui some are at 1:1,000,000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsib1e for their reproduction. In addition,
a set of colored l.:1,000,000-sca1e index maps of selected fish and
wi 'ldl i fe speci es has been prepared and may be found i n the At1 as
that accompanies each regional guide.
1. Southwest. Arctic arayling are found in clearwater streams
oTiltre gristol Bay and Alaska Peninsula drainages south to
approximately Port Heiden. Gray'ling have been stocked in
sbiected la-kes on Kodiak Island (Murray' pers. comm. ).
Grayf ing are not present on the Aleutian Islands or in
streams- on the sou'th side of the Alaska Peninsula (ADF&G
1978). Large grayling are found in the Ugashik, Becharof,
Nuyakuk, and Togiak river drainages (ADF&G 1978; Russell'
pers. comm. ). (For more detailed narrative information, see
volume 1 of the Alaska Habitat Management Guide for the
Southwest Region. )2. Southcentral. Arctic grayling are found in several c'lear-
wafiffiiffiaries and lakes within the upper Copper River and
Susitna River drainages and in a few cleartrater tributaries
of the lower Copper River. Grayling are not found on the
west sjde of Cook Inlet south of Tyonek (ADF&G 1978). They
are also not native to the Kenai Peninsula but have been
stocked in several Kenai Peninsula lakes, which now contain
self-sustaining populations (Enge1 19i1). (For more detailed
narrative informatjon, see volume 2 of the Alaska Habitat
Management Guide for the Southcentral Region.)
III. PHYSICAL HABITAT REQUIREMENTSA. Aquatic1. Water quality. Gray'ling prefer clear, cold lakes and streams
lTDFmTffi.); with different life stages frequent'ly occurring
in different locat'ions within a drainage. Grayling generally
feed during the summer in rivers and streams that may freeze
solid or dry up during the winter, and they often overwinter,
therefore, in the same system in areas unsuitable for summer
feeding (Tack 1980). The basjc water chemistry of streams
that support gray'ling varies by geographic.area and reflects
the character of mineral types in the area (ibid.).
a. Temperature. Increasing water temperatures and spring
Tlo6-dl ng appear to stimul ate spawni ng (Armstrong 1982 ) .
A water- temperature of around 4"C triggers spawning !lthe interior streams of Alaska (Tack L973, ADF&G 1983)
and in Western A]aska (Alt 1976); however, spawning
activities have been observed at temperatures ranging
184
from 3.3oC at the inlet to F'ielding Lake_ in. Interior
niitfu-(Woi.ik 1954) to 16.7'C at Wier Creek in the
;;;i;;t I";;a (craig ano Poul in 1e75) ' La Perriere and
Ciiiion (1973) 'found grayling tolerant of temperatures
in "*i.ti of '20;C ,nd..-'lab-oratory conditions. Field
ouservations indicate that juveniles and fry are
ioie.ant of high temperatures but that small subadults
una-uOuitr teni to avoid water temperatures-above 16"C
in..J- rg64, Schallock 1966, 1,.1oici k 1955-) '. . Gray'l i ng i n
ih;-i.;aie'Lakei area djsplayed- s'ig_n1 of discomfort and
e*p..ieiceO unusual 1y t''igl -mortal i ty when- taken i n
*u[..r with a temperature 6t 17'C (Woicjk 1955, cited in
i,i;i;;[ igTs j .
- -
bevet opment of esss to hatch'ins i s
Jir.iit, infiuenced by water temperatures, .T.emPeraturesir'u.iitigi sti cal iy .ise duri ng ' the i ncubat'ion. peri od;
iherefore the eggs are not usuhlly exposed to freez'ing.
No reference to""upper or lower lethal temperature data
for eggs was found jn the avaj.lable literature', i- rL^
b.
c.
i;;;il"iu.it..--lrt optimum pH value was found in the
]ffi] Measurbd val ues of several .i nteri or
streams, however,-iangeA from 6..2 (Netsch.1975] to 9'0
ii;iil;;s igiei. ' Rusiel t (1e80) _report_s that southwest
ii;;k;- ;.;;;;''u.. also naturallv s'lishtlv alkaline
d.
(7.1-8.5) .
ojssolved ox.vqen (D.0. ). Some gray'ling can surv'ive over
ffientrat'ions of less than ! ppq
(nogusLi and
- iact 1970).; however, Tack - (-1973) qnq
Wiiiiams and potterv'ille'(1981) found that D.0.s of 0.6
ppm anO O.S ppm,- respectiu.ly, resulted in winter kills
ih seu.rat inteiior ind southcentral lakes. No optimum
D.0. val ue was found i n the I i terature; however '
measured concentrat'ions during periods_ of observed
o.iuiino abundance have ranged- fiom 0.6 Ppm (Bendock
igg"gt fo ZL ppm (Pearse L974) in. interior streams.
Measured D.0. i6ncentrations during the summer months in
several Southwest Alaska waters indicate an average D.0.
of around 10 PPm (Russell 1980).
iurbiditv. Hiah ievels of turbidity may abrade and clog
Tisfffil;, .eiuce feeding, and cause fish to avoid some
u..ut" (Reiser and Bioinn 1979) ' Turbidity .and
sedimentation may smother food organ_'isms- and reduce
o.irliv--producil"uitV (Bell 1973, LaPerriere et al.
ib$ j ." friniO wate-r riuy absorb more sol ar radi ati on
than clear water ano may- il'us indirect'ly erect thermal
barriers to m'igration (Reiser and Bjornn 1979 ' Van
Nieuwenhuyse 1983).Si;;ah inalyses ' of caged gravl-i ng !e-ld . i n. mi ned and
unmined streams (LaPerri-ere it-al. -1983) inaicated that
g;;vi i.g - in it'. turbi d , mi ned w.aters were not capabl e. of
ioiiti ng .invertebrate prey. Th'i s may be due to the
185
2.
observed reduction of i nvertebrate abundance i n the
mi ned stream or to the i nab'i 'l 'ity of the grayl i ng to
locate prey in the turbid water. Studies conducted on
the Susitna River indicate that gray'ling avoid high-
tur"bidity waters (Suchanek et al. 1984).
Water quantity. Sufficient water velocity and depth are
reqtTG[-To eI-'1ow adequate intragravel water flow during egq
and alevin development. Low flows during incubation could
result jn desication or freezing of developing eggs and
alevins (Woicik 1954). High velocities or f'looding could
cause low fertil'ization, egg dislodgement, and/or displace-
ment of young-of-the-year (Y0Y) out of their rearing areas to
less favbrabie s'ites, resulting in direct morta'lity (Nelson
1954; Tack 1971, I974). Excessive velocjties may also impede
migrating fish (Hal'lberg 1977, MacPhee and Watts 1976)
The upstream migration of grayling usually coincides with
high f'lows resulling from spring breakup (Krueger 1981). In
studies of Deadman Creek, tributary to the Susitna River, the
upper reach, which is characterized by an abundance of 'large'
dbbp, pool-type habitats, contained a higher summer popyla:
tioh of grayiing than the middle and lower reaches, which
were more-strltlow (sautner and Stratton 1984).
Arctjc grayling Spawn in a wide range of current velocitjes
and oefltni. -woicjk (1954) reported spawn'ing _ in "s1ow,
shallow' backwaters" in an inlet stream to F'ielding Lake.
Warner ( 1955) observed gray'l i ng i n the same stream spawn'ingjn surface current veloclties of about 1.2 m/sec in depths of
1.6 cm. Surface current velocities measured in territories of
22 males jn the outlet of Mineral Lake (Interior Alaska)
ranged from 0.34 to 1.46 m/sec, and territorial depths ranged
from 0.18 to 0.73 m (Tack 1971).
Newly emerged fry are found in protected areas where current
velocities are extremely low. Typical emergent fry-rearing
areas jnclude shallow back waters and flooded stream margins
and side channels (Krueger 1981). 0lder YOY fish occupy
progressively faster waters. Aquatic habjt_at occupied by
i^eaiing YOY fish in selected bog streams along -the Trans-
Alaska Pipeline System (TAPS) had mean column veloc'ities of
0 to 0.15 m/sec and water depths ranging from 0.09 to 1.07 m
(Elliott 1980). Juven'ile and adult fish jn bog streams along
the TAPS were found ho'lding in mean current velocjties
rang'ing from 0.175 to 0.262 m/sec and were found at water
deplhs- ranging from 0.2 to 1.07 m. Juvenjle grayling .il1trjbutariei to the Susitna River appear to rear in areas with
water velocities under 46 cm/sec (ADF&G 1983).
Little is known about gray'ling migration to overwintering
areas; however, current velocit'ies in overwintering sites are
probab'ly very 'low ( i bi d. ) .
Substrate. Arctic gray'ling have been reported to spawn over
E-'ifiIlil|nge of substiatei, including mud, silt, and gravel3.
186
uD to 4 cm in d'iameter (ib'id). The following are examples of
observed spawning substrates in Alaska:i--- rin. lt cm)-gravel (warner 1955)o ,,pea-size" g';uull ir,'-tf,. outlet of Mineral Lake (Tack
1e71 )" Sand-to-small-cobble, w'ith coarse sand and. gravel lo
about 2.5 cm 'in diameter in fouLinlet tributaries to
iv.. t-ut. n.ut retCnitun (Cuccarease et al' 1980)
" R;i;tive'ly -fine (3.8 cm diameter) gravel , with most
miterial -less than I.25 cltr in outlets of two Kenai
Peninsula lakes (Hammerstrom and McHenry' pers. comm.'
c'ited in Krueger 1981)
iunO and fine-gravel iubstrate, about 0.6 cm 'in diameter
in tne outlet -of tea Lake near the TAPS (McCart et al.
te72)ii t t' ana f i ne sand overl ai d by or.ga_n-l.c detri tus i n
Niiiion nottar Cieet<, a'tong the tApS (Elliott 1_980)
sirt overlaying grave'l jn-the main stem colville River
(Bendock 1979): Riiiil,: r i- 1,1
",;u,""'o
il'fi;ffff; [['i'.i,111 .'''J lL] n il],,
0.75 mm to 28.1 mm at the outlet of Mineral Lake (Tack
1e73 )
Gravel substrate provides cover, decreases the chances of
atiioog.dnt, -una'lessens swimming. stresses 11. early 'litg
history stages, probably resulting in higher,119Yin survjval
than for th6se nitctring"on exposed substrate (Kratt and Smith
IgiT).- In the Susiina- River, adu.lt grayling^use- rocks wjth
diameters over g -cm ior protective iover (Suchanek et al.
1e84).B. Cover Requirements
t'tewiv emerqed f ry have I im'ited swimmi ng abi I iti.es , and tlty
riiio'ol
-'in'"irrurldw, -protected stream aieas with cover, 1ow
.rii.nt velocjties,' and an abundance of food . items'
fr"e!uia. banks, wiih shadows from boulders and overhanging
veqeiation, coniribute 'important cover for these rearing fry.
lri.nii. iitn (age one year and o.1der) progressively.move.to
fiiier and deepei-stream reaches (Vascotto- tgZO).- 0lder fish
.orronfV use ''logs, boulders, and turbulence for instream
.ou.. (itallberg, -pers. comm., cjted in Krueger 1981; Sautner
and Stratton 1984).
IV. NUTRITIONAL REQUIREMENTSA. Food SPec'ies Used
Grayl.ihg are opportunistic feeders, able to uSe a wjde range.of
food i|.rr, ;;i- th.t - prey priman.i'ly on immature and emergi ng.
aquati;-"i;'t.;i; (|."n''tfto'ig 1982). - Bishop (.1.971) found YgY
giivring in the 'MacKenzi6 River system .fgedjlg ,on immature
iluv?r i.i (ipnemeroptera); caddi.sf.t i.es .(Trichoptgla),; a-nd _trueflies, mosquitoes, unO'*'iag.t (Diptera). Elliott (1980) found
187
B.
that jmmature midges (Chironomidae) were the most frequently
consumed taxon Uy VOV grayling in spring, rapid-runoff, and bog
streams crossed by TAPS. Enge'l ( 1973) found that gray'l i ng eggs
comprised the bulk of the diet of iuvenile.grayling found
downstream of spawning adults in Crescent Creek on the Kenai
Peninsula. Adulis feed primari1y on immature mayf1ies' stonef'lies
(Plecoptera), dipterans, and caddisf]ies (Bishop .1971, Bendock
igeO, 'Craig and' Wells 1975, McCart et al. L972). In. lakes,
zoopiankton may make a significant contribution to the diet
(yoihihara L97i and Wojcik 1954, cited in Armstrong -19.8?). In
three lakes in Southwest Alaska, Russell (1980) found Trichoptera
larvae and adults and cyc'lopoid copepods to be the most cormon
food i tems. salmon eg-gs, smel t eggs, and shrews have been
observed in grayljng stomachs from the Naknek River in the Bristol
Bay area (nussdl 1 , -pers.
comm. ) . 0ther food i tems i ncl ude adul t
ch-i ronomi ds and odher di pterans ; co'l eopterans (beetl es ) , and
hymenopterans (bees, wasps) (Craig a.nd tlJel I s 1.975); gastropods
(ftojcii< tgS+, iusse'll 1980); isopods (ADF&G 1977); Pl9!t material
1C.iig ana wetts t9i5); fiih (McLart et al. L972, 1^1illiams 1969);
and lemmings (Alt 1978, Reed 1964).
Types of Feeding Areas Used
nlwty emerged f"y have limited swinming abilities and spend the
firsi summer neai their hatch site (Tack 1980). They school and
feed in shallow lotic habitats with low current velocities where
product'ion of aquatic invertebrates is _hi9h (Cuccarese et al.
iggO). Immediately after spawning, adults and large -iuveniles
move to upstream locations or into.tributary streams or lakes rich
in food (tack 1980). Tack (i980) found that in 1arge, rapid-
runoff rivers, grayling consistently home to.their summer feeding
streams and telOing locations. Vascotto (1970) obsgrved _thatduring the summer months gray'ling were found almost exclusively in
poolsi where they establiahed feeding territories and, within each
ieeding territory, a feeding range where all feeding activities
took place. In pools with a strong current, distribution was
related to the strength of the current and the availability of
food in the benthic drjft, with the larger fish holdjng near the
upstream end near the center and smaller fjsh distributed down-
slream and to the s'ides (Tack 1980, Vascotto and Morrow 1973'
ADF&G 1983). 0ther l'iterature also indicates that rearing-gray-
ling concentrate in the lower reaches of a stream and that larger
(olier) fi sh are found further upstream (Ha1 1 berg 1978' Tack
1e71).
Factors Limiting Availability of Food
Grayling are vjsual feeders, relying primarily upon benthi.c drift
for- nutiition. During periods of high, muddy water, this drift is
unavailable to them.
Schallock (1966) suggested that grayling and slimy sculpin (Cotlus
.ognutrii 'tuv'complele for food. - Thdugh some dieta'ry oveFlTF
[ffieen the two ipecies does occur (Sonnich.sen 1981),. it is
unlikely that competition for food takes place (Moyle 1977).
c.
188
V.
D. Feeding Behavior
M;;i giuyiing feed on the water surface or on the drift at mid
i.pif' " (GrColto--ig70); they al so feed off the bottom during
periods ot--reJuceA benthii" O.iit (Morrow 1980, Woicik 1954)'
bruviing jn lakes tend to feed more on the bottom than those'in
iir[url"tn.*tirong -igBZ). Feeding behavior varies with the size
of the individual and jts hiera-rchical status (Vascotto 1970'
vascotto and Morrow 1973). Tack ( 1980) suggests tl'9t the
outmigration of iuvenile and spawned-out adult fish may a'llow YOY
fish to r.u. u-no feed'in natal streams without competition'
Grayling u.. uCiiu. feeders during t1q summer, ceasing to feed
o.f V uf Ourf.*tt in..J 1964).. drayl ing also feed during the
winier (Alt Ig76, Bendock 19ti0). Piespawning and spawn'ing Iltl
take food oniV-'casually ui it drifti pas[; spent fish feed
iiliu.iv- tsi il''dp !s7r, ciais and wel I s 1e75) '
REPRODUCTIVE CHARACTERISTICS
A. Reproductive Habitat
Grayl i ng ,iruiiy --ipqWn
i n unsi I ted rapi d-runoff streams , bog
(tundra una- toothiil) streams, and lake inlets and outlets'
iiirnl.g does not occur to any ex.tent ^i
n spr!1s;fed s.treams or
s j I ted rap.id-runoff streams ifact ^1^910)
. 51i th j n ri vers and
streams, g.uyfing- usualfV ipawn' ll.tiffles comp-osed of gravel or
iltbil- (sde I I I .A.3. , Substhte, thi s- report) . Grayl i ng have a'l so
been reported spawning in- stow, shallow backwater areas (Woicit<
fgS+1, in i tui. ovei large .uUUte and vegetated :]]_t,-(Bendockiq7gi, in a stagnant pond amon_g sedges over an organic bottom
(fu.i. 1980); t.d -ou.r^ mira ln a s'lough (Reed 1964)'
B. Reproductive Seasonaf itY --Grayling poirl;i;;;; in lfaska sp_awn between late April and earlv
Juiv, "ith most spawn.ing tak.ing pllge between mid MQy and mid June
ig.;,dotr n;l-g-,-nobuiii ind rac[ 1970, schallock 1966, Warner 1955'
bt;i;ii f gSa'1.' f n'-inp Bri stol Bay .are-a, gray'l llg general ly spawn
il"M;i (nrd{.tt -1e8ij)-. In 1e82 ald 1e83,-sr9{li_ns in,il,S^ susitna
River araina!e'ipawiea from late May to mid June (ADF&G'1983'
Sundet ana Wellei' tge+). fhe spawnini-per.iod often coincides w'ith
the rising wale" temperatures' and Tlooding of spring breakup'
Grayling iypicitty ascend to spawn!19 sites as soon as flow
conditions -permit passage (Krueger 1981)'
C. Reproductive Behavior
Males entei td spawning grounds and -establish territories in
rjffl. ur.it, which they'vigorously defend aga-inst qthel males'
Femal.s..*uin in deep pools'and enier the riffles only for short
per.iods to"'ipurn (i;;[ fgZf). The spawn'inq act'invo]ves'intensive
simultaneoui'booy:u;.ntng ano vibrating; 16 redd is dug'-but small
depressiotir-rlruif V .tsuit from the spiwnl.ng actiYily. , During the
spawni ng u.i- tf,"" poiterlor port'ion o.f the femal e' s body may be
forced in;-'th;'-giuu.i by if'. male's -tai1 working v.ertjcally
titiill.' ' rggi ird iimutfineously fert'il'ized and dep_os'ited 2 to
3 cm Uetow "dhe giavet trtiii. (fratt and Smith L977, Van Wyhe
189
D.
1962). The eggs are adhesive prior to water-hardening and have a
slightly highei specific gravity, enab'ling them to sink to the
botlom - rapiOly, where they are covered by settl ing materia:l
loosened during the spawning act (Brown 1938, lrlarner 1955). _The
female resumes- her former r-esting posit'ion after spawning.. Both
Sexes may Spawn more than once wjth various partners _(Krueger1981). itre iluration of spawning activity may range from four days
to two weeks (Craig and Pouljn 1975, McCart et al. 1972, Tack
I97I, Warner 1955).
Conflicting observatjons exist in the literature concerning--an
apparent diurnal pattern of spawn'ing activ'ity. Van Wyhe (1962)
ahh Warner (1955) reported that most spawning activity occurred
between 8:00 P.M. and 4:00 A.M. Russel'l (pers. comm. ) has also
observed grayling spawning at night 'in Lower Talarik Creek in
Southwest - Alaska-. Qther observations, however, indicate that
spawni ng act j vi ty occurs on.ly duri ng dayl i ght hours and p.robably
ceases iuring the evening (Bishop I97I, Kruse 1959' MacPhee qnd
Witti L976, -Scott and drossman' 1973, Tack and Fisher 1977).
Wi I I iams ( 1968) noted that grayl ing from Tol sona Lake near
Glennallen, Alaska, entered Bessie Creek to spawn only at dusk and
after dark. In contrast, gray'ling from Moose Lake entered Qur
Creek during all hours (ibid.). Williams hypothesized that the
difference may be due to the lack of cover in Bessie Creek.
Tack (igao) -suggests that since grayling adults home to the
feed'in! stream lnnually they probably also home to their natal
stream to spawn. Tagging stud'ies'in the Susitna River drainage
indicate th;t the maibrity of arct'ic grayling do return to the
same stream year after year, in many cases returning to the same
specific arei with'in the stream (ADF&G 1983). Craig 9!d Poulin
(igZS) a1 so feel that some gray'l ing return annual 1y to a
particular stream to sPawn.
Age at Sexual MaturitY
The point at which sexual maturity is rea-ched varies and is
pionu'Uiy tnot. rel ated to s j ze than -to age (Armstrong _ 1982 ) r. . I n
Itre intirior systems and the lower Kuskowkwim River' lower Yukon
River, Seward Peninsula, and Tanana Rjver, fish reach maturjty by
aqe four, five, or six (Alt 7977, 1978, 1980; Armstrong I9B2;
W6jcik 1055). Most grayling begin spawning in the Bristol Bay
area at age five (Russell 1980). Grayling from Crescent Lake on
the Kenai- Penjnsula mature at age three-or four (Engel 1973).
Grayling in the upper Susitna River mature at- age. four ql five
(AD?&G -1983, Schmiat and Stratton 19_84). In the Northslope
systems, most grayling appear to mature later, at ages,:f--.to-nine
(Armstrong lgriZ,-Craig'and Wells 1975).. Grabacki (1981) found
inat upper Chena River (Interior Alaska) popu.lations subiect to
heavy 'fishing pressure showed slower individual . growth -rates'younger average dg€, and lower natural mortality than populations
in areas free of fishing Pressure.
Longevity is variable, wi'th northern popu'lations genera'l'ly l iving
1 onler than southern popul ati ons . I n some unexpl oi ted
190
populations' a high percentag-e- Jtu: beyond.8--y-ear.s'. with some
iui^v jvtng ui to af leist age _22 (de_Bruyan and McCart 1974' Craig
and Poulin igZS, Craig and Wells 1975).
E. FrequencY of Breeding
eraytint"spawn annuaily upon maturation (deBruyan.and McCart I974,
Craig aiO iletls 1975, Engbt !973, Tack 1980, 51illiams 1969).
F. FecunditY
Fecundit! varies, apparently. dependi!9 on the size of the fish and
the ttoit. y1jliia;; (196ti) sampled- eight grayling from Bessie
Creek, which connects' Tolsona and Moose lakes, an.d found an
average iecundity of 4,490 eggs per fjsh. Schallock (1966) found
an uu..ug. fectindity of SISSO eggs from 24 Interior Ajaska
giuyi'ing." Individuai fecundities ranged from 1,700 eggs for^.267
il*-iong'iish (fork length) up to 12,i50 for a 400 mm-1ong fisft'
An averaqe fecundity of g,gOg was found for 20 grayfing-from the
yukon Te"rritory (deBruyan and McCart L974, cited:.n Armstrong
igtiti, *ith no-silnificint correlation between fecundity and fish
1 ength.G. Incubation Period/Emergence
Embryo J.u.t opr.nt i s" rapid ( 13 t9_ .32 daJs-), and i s di rectly
corrLlated with water temperatures (Bishop L97L, Kratt and Smith
igtti. kruit and Smith (1977) found.that arctic gra.yling eggs in
northern Saskatchewan hatched in 32 days at a mean da'ily teTPifg:
ture of 5.8"C. F.ield studjes in Interior Alaska by Warner (1955)
and hJojcik (1954 and 1955) indjcated that at an average- water
temperJiure of 7.8oc eggs eyed in 14 days and
-h_at_c]n^ed.
in 18 days,
and eggs incubated at-i mein temperature of 15.5"C hatched in B
days. In another field study,-qgg.s incubated at an average wqlel
temperature of 8.8"C eyed a[-tO-iays and began hatching.in-13.1
i;t!- fgiinop 1971). ntevins remain in the gravel and almost
coirpteief V absorO if'"ir yolk sacs before emerg'ing (Kratt and Smith
lgiil. -vi,rng-of-the-yea-r are present by June 5 in the Bristol Bay
area (Russell 1980).
VI. MOVEMENTS ASSOCIATED t,lITH LIFE FUNCTIONS
A. Home TerritorYAll tiie pnas"es, includjng the life functions_of spawning, rearing
of young, ieeOf ng, and o-verwi nteri ng, usual 'ly take pl ace wi thi n
the-semiConfined lnvironment of one drainage or watershed system.
UsualfV iome locations within a drainage.are better suited than
others" for iupplying seasonal life-funct'ion needs, and .grayling
therefore ofteri 6xtriUit complex migrational patterns and requ'ire
unrestricted movement wjthin a system (Armstrons 1982).
Spawning territories vary in siie, depending upon such factors as
stream "widlh, water depin, current velocity, channel configurg-
tion, and ipawner densily. Tack {1971) . described 22 male
territoiies ai genera'l1y ovil , 1.8 to 2.4 m wide and 2.4 to 3.0 m
1 ong.
191
Timing of Movements and Use of Areas
Adulti move from overwintering locations to begin an upstream
prespawni ng mi grat'i on under the i ce i n 'l ate wi nter or early
iprihg. The prLspawning migration typica'l'ly. lasts from two to six
wbeks, depending upon the distance traveled. Grayling move into
smaller dributaries to spawn (avoiding spring-fed streams and
silted rapid-runoff streams) as soon as the ice is out and the
water temperatures rise to about 1"C, usual'ly in May or June
(Armstrond tggZ, Sundet and Wenger 1984). Immature fish general1y
iollow cl6se1y behind adults. lmmediate'ly after spawning, many of
the adults move out of the smaller streams to up-river Summer
feeding areas, but most iuveniles remain in sma'll streams until
I ate A--ugust or September. From September through December,- .as
temperat-ures drop and i nstream fl ow and food avai I abi 1 i ty
detbri orate , there i s a genera'l downstream movement of a1 I age
classes to more favorab1e overwintering areas (Grabacki 1981'
Netsch 1975 , Tack 1980 ) . Common overwi nteri ng s i tes i ncl ude
intermittent pools, under the ice in large rivers, deep.-lakes'
brackish river deltas, and spring or ground-fed areas (Bendock
1980, Tack 1980). Lake-dwelling popu'lations move into tributaries
to spawn in the spring and may-return to the lakes shortly_after
spawning (Engle tgZg), or m.ay rema'in jn the tributaries until fall
(bauntei and-Stratton 1984). Gray'ling leave.Deadman Lake in mid
iune and do not return until early September (ibid.).
Migration Routesn river'S or stream's source of water affects the migrational
pattern of grayling within that system. _ Glacier-fed systems in
tne interjoi tend to be used mainly for overwjntering or as
migration routes to other systems; spling-fed _systems are used
primarily for feeding, with some overwintering for those systems
bntering- the Arcti c bcean; bog-fed systems may p_rovi de su'itabl e
spawning and feeding habitat; large unsilted runoff waters may be
uied foi spawning, feeding, and overwintering (Tack 1980).
VII. FACTORS INFLUENCING POPULATIONSA. Natural
Excessive water velocjties can cause low fertil ization, egg
dislodgement, and alevin displacement (Ne'lson 19S_i; Tack I97L,
Ig74) .- Low water duri ng the summer months wi I I concentrate
grayiing, making their population more available to.fishing
pressur6 (Tack tSZs). High water temperatures (above 16"C) during
the sunrnei and low water and D.0. levels during the winter can be
detrimental.
B.
C.
Predation on grayling eggs and alevins by other.fish could_s.ignif-
icantly reduce population levels (Krueger 1981). trlhitefish were
reportld preying 'upon arctjc grayl ing eggs at the out'let of
Miheral Lake (Tack 1971). Other fishes, includ'ing rainbow trout
(Salmo gat1.-d4li Richardson); arctjc char (S.alvelinu9. 9]pi!Ys(Salmo gairdneri Richardson); arctic char (5alvel'lnus aipl!ys
iff nn*uffirnd whitefish (Prosopiuqr cvl infficeum TPaTIIIIT
northern -pf t<e (Esox lucius tmfi6usI;anilTongi-ose suckers
t92
(Catostomus catostomus IForster]), also .consume arctic- grqyllng
:;s-%;ti.vt'r nop'igii'-miip."" and watts !e76, Alt 1e77)'
B. Human-related , r! -[nV AlsturUinces within a system that d.egrade_qrayling, spawning'
reari ng , or
-f
eeJi ng habi tats", de-grade later qual i ty., or bl ock f i sh
migration ,ori.t "tuy adversely affect poqf uJi:1.*J^tutl s of
griyling occupying that. system. A summary -of poss'ible impacts
from human-r.iit.O- activ'ities includes the following:o Alteration of preferred water temperatures, PH, dissolved
oxygen, and chemical comPosition-o Alteraiion-of preferred water veloc'ity and depth
" Alteration of preferred stream morphologyo Incruui.-in-tutp.nded organic or mineral materialo Increase in sedimentationo Reduct'ion i n permeab'i 1 i ty of substrateo Reduction in food suPPlYo Reductjon in protective cover (e.g., overhanging stream
banks or vegetation)o Shock waves in aquatic environmento Human harvest
(See the l;;;ctt ot t-anO and Water Use volume of th'is series for
iaJitionul 'informati on regardi ng 'impacts ' )
IX. LIMITATION OF INFORMATION
A great urount-ot information has been collected on the life history of
arcti. g.uyiing it nfiifj, puiticularly in the Interior Region and
along the 1APS, Uut there'arri-stitt gap; in our knowledge critical to
rhe future';;.;.*ni -of grayling is' resource development (habitat
alterations)"ln.i- angler pi.ttu.d continue to increase' A better
understanding of tni Oynainics of exploitation, early life history'
stock separalion, feeding ft.Uitt, -grdyf ing stockin.9,. ll"e. validity of
aging oy scite analysit, inJ-if'e effecfs of various habitat alterat'ions
isnecessary.Thereareveryf.y.studiesonlheeffectsof
environmental changes on u..ti."g.uyling in Alaska (Armstrong 1982'
Grabacki 1981).
VIII. LEGAL STATUS
The Alaska DePartment of
manageria'l authoritY over
Fish and Game, Division of Sport Fish' has
arctic graYling.
Al aska
McLean,
pp.
ADF&G, comp. 1s77. A fish .tiTii5i,'rtl ,^"r.u... inventorv of the
Peninsula, Aleutian Islands, and -ari1!o-t -Bay-. areas IR'F'
K.J. Detun.y, ;;; g.A. C.ors,'comps.l. Vol. 2: Fishegies. 556
. 1g78. Alaska,s fisheries atlas. vol. 2 [R.F. McLean and K.J.
-TT;ney,
comps.I . [Juneau. ] 43 pp' + 153 maps '
193
ADF&G. 1983. Susitna Hydro Aquatic Studies. Phase 2: Basic
Vol. 5: Upper Susitna River impoundment studies L982.
appendi ces.
data rept.
150 pp. +
Alt, K. L976. Inventory and cataloging of North Slope waters. ADF&G, Fed.
Aid in Fish Rest. Ann. performance rept. Vol. 17. Proi. F-9-8,
Job G-I-0.
. 1977. Inventory and cataloging of arctic area waters. ADF&G,
-Ttd.
Ai d i n Fi sh Rest. Ann. performance rept. Vol . 18. Proi . F-9-9 ,
Job G-I-P.
. 1978. Inventory and catalog'ing of sport fish waters of Western--AT-aska. ADF&G, Fed. A'id in F'ish Rest. Ann. performance rept.
Vol. 19. Proi. F-9-10, Job G-I-P.
. 1980. Inventory and cataloging of sport fish and sport fish
TTers of Western Alaska. ADF&G, Fed. Aid in Fish Rest. Ann.' performance rept. Vol. 21. Proj. F-9-L2, Job G-i-P.
Armstrong R.H. 1982. A review of arct'ic grayling studies in Alaska.
Contrib. N0.6, Alaska Coop. Fish Rest. Unit, Unjv. Alaska, Fairbanks.
6o pp.
Bell, M.C. L973. Fisheries handbook of eng'ineering requirements and
biological criteria. Fisheries-Engineering Research Program Corps of
Engineers. N. Pac. Div., Portland, 0R.
Bendock, T.N. L979. Inventory and catalog'ing of arctic area waters.
ADF&G, Fed. Aid in Fish Rest. Ann. performance rept. Vol. 20. Proi.
F-9-11, Job G-I-I.
. 1980. inventory and cataloging of arctic area waters. ADF&G,
-Ttd-.
Aid in Fish Rest. Ann. performance rept. Vol .2L. Proi. F'9'L2,
Job G-I-I.
Bishop, F. 1971. 0bservations on spawn'ing habits and fecundity of the
arctic grayling. Prog. Fish Cult. 27 212-19.
Brown, C.J.D. 1938. 0bservations on the life-history and breeding habits
of the Montana grayling. Copeia (3):132-136.
Craig, P.C., qnd V.A. Poul'in. 1975.Movements and growth of arctic
uvenile arct'ic -char (Salvel inusiraylin! (Thymallus arct'icus) and iuvenile arct'ic char (Sqlvelinus
al pi nus ) 'in a srm-l I affistream, Al aska. J . Fi sh . Res. Bd. Can.?lP!ttYs)--i322689-697.
Craig, P.C., and J. Wells. 1975. Fisheries investigations in the Chandalar
River region, northeast Alaska. Pages 1-114 in P.C. Craig, Bd.
Fisheries-'investjgations in a coastal region of-the Beaufort Sea.
194
Canadian Arctic Gas Study Ltd./Alaskan Arctic Gas Study Co. Biological
Report Series 34(1).
Cuccarease, S., M. Floyd, M. Ke'|1y, and J. LaBelle. 1980. An assessment of
environmental effects of construction and operation of the proposed
Tyee Lake hydroelectric project, Petersburg and Wrange11, Alaska.
AEIDC, Univ. Alaska, Anchorage.
deBruyan, M., and P. McCart. 1974. Life history of the grayling (Thymallus
ircticus) in Beaufort Sea drainages in the Yukon Territory. Chap. 2 in
F.fM--c0art, ed. Arctic gas biologica] report series. Vol. 15.
El I iott, G. 1980. First interim report on the evaluatjon of stream
cross'ings and effects of channel modifications on fishery resources
along the route of the Trans-Alaska pipeline. USFWS' Special Studies.
Anchorage, Ak. 77 PP.
Enge1, L.J. 1971. Evaluation of sport f!sh slogking on the Kenai Peninsula- -Cook Inlet areas. ADF&G, Fed. Aid 'in Fish Rest. Ann. prog. rept.
Vol 12. Proi. F-9-3, Job G-11-F.
Enge1, L.J. 1973. Inventory and cataloging of Kenai Peninsu'la, Cook Inlet,- ind Prince l,{illiam Sound drainages and fish stocks. ADF&G, Fed. Aid in
Fish Rest. Ann. prog. rept. Vol 14. Proj. F-9-5, Job G-I-C.
Grabacki, S. 1981. Effects of exploitation on the population dynamics of
arctic gray'ling in the Chena River Alaska. M.S. Thesis, Univ. Alaska,
Fai rbanks.
Ha11berg, J. 1977. Arctic grayling in the Tanana Rjver drainager lDl&9'Fed. Aid in Fish Rest. Ann. performance rept. Vol 18. Proi. F-9-9'
Job R-I.
. 1978. Arctic grayling in the Tanana River drainage. ADF&G' Fed.
---TlT i n Fi sh Rest. Ann . performance rept. Vol . 19. Proi . F-9-.10 'Job R-I.
Kratt 1., and J. Smith. 1977. A post-hatching sub-gravel stage in the life
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199
Btrbot Life History and Habitat Requirements
Southcentral Alasha
Y
)" " o" .tap2\-o
Fap 1. Range of burbot (ADF&G 1978)
I. NAMEA. Cormon Name: BurbotB. Scientific Name: Lota lota (Linnaeus)
C. Species Group RepffiniE-tion: Burbot is a member of the codfish
family (Gadidae) and is the only species found strictly in fresh
water.
I I. RANGEA. Worldwide
Distribution of the burbot is circumpo'lar in the northern
hemisphere. Several subspecies of burbot are present in fresh
waters of Eurasia and North America from the Arctic 0cean
southward to about 40oN. It is absent from Kamchatka, Scotland,
20r
Ireland, Nova Scotia, most is'lands, and the west coast of Norway
(Scott and Crossman 1973).B. Statewide
Burbot occur throughout mainland Alaska, including nearly all of
Interior, Western, and Arctic Alaska (map 1). Burbot are absent
from most coastal watersheds of Southeastern Alaska, the Kenai
Peninsula, Kodiak Island, and the Aleutian Islands chain (ADF&G
1978). Burbot are widely distributed in large g'lacial rivers of
interior Alaska, near the confluences of trjbutary streams and in
many 'lakes (Peckham 1979).C. Regiona'l Distribution Summary
To supplement the distribution information presented in the text,
a series of blue1ined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale,
but some are at 1:1,000,000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition,. a set of colored 1:1,000,000-sca'le index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.1. Southcentral. Burbot occur throughout lakes and intercon-
necting waterways of the upper Copper-Susjtna rivers area.
The main Susitna River and 'its larger tributarjes, the
Yentna, Chulitna, Talkeetna, and Skwentna, support burbot
populations (ADF&G 1978). 0n the Kenai Peninsula, burbot are
present only i n Juneau Lake, where they were probably
introduced ( ibid. ). In the Prince t,{i 1 I iam Sound area, a
native population is present in McKinley Lake near Cordova
(ibid. ). (For more detailed narrative information, see
volume 2 of the Alaska Habitat Management Guide for the
Arctic Region. )
III. PHYSICAL HABITAT REQUIREMENTSA. Aquatic
1 . Water qua'l i ty:a. Dissolved oxygen (D.0.). Little is known about oxygent. Sorokin (1971) reports that
burbot eggs can deve'lop only when the oxygen content in
the water is fairly h'igh and that spawning grounds
usually have an undercurrent of fresh water ensuring a
supply of oxygen. State of Al aska water qual i ty
standards for growth and propagation of freshwater fish
call for D.0. levels greater than 7 mg/l (ADEC 1979).
Turbidity. Prolonged exposure to turbidity can irritateTfih-fiIs, interiering' with respiration (Bell 1973).
Suspended material in water can smother food organisms
and lower primary productivity, making spawning areas
unusabl e (i bi d. ) . Li ttl e i s known about turbi djty
levels that are harmful to burbot. Chen (1969) reported
that burbot in the Tanana and Yukon rivers were more
b.
202
2.
abundant in the si1ty, main rivers than in the smaller,
clear tributaries. Chen found that burbot ran up the
tributaries more often during high water, when the
tributaries' water turned silty. Burbot eggs are unable
to develop on soft, silty bottoms (Volodin 1966).c. Sal i ni ty. Burbot i s the on'ly freshwater species of the
aod Temily and generally avoids brackish waters. This
fact is evident in its distribution, as it is absent
from most islands within its range (Scott and Crossman
1973, ADF&G 1978). However, burbot have been reportedin the brackish waters of the Yukon Territory's coast
and j n the MacKenzie Ri ver del ta i n Canada, where
salinjties were less than 5 ppt (parts per thousand)
(Percy 1975, Kendel et al. 1975). The fish moved from
the brackish water upstream to lakes and rivers in latefall for spawning.
Burbot eggs are more tolerant of brackish water and
develop normal'ly at 3 to 6 ppt salinity (Jager et al.1979). Fertil izatjon, embroyonic development, and
hatchjng were observed in salinities up to 12 ppt, but
the mortality rate increased at later embroyonic stages.
At a salinity of 14 ppt no larvae hatched (ibid.).
Water depth and velocity. Adult burbot usua'l1y reside in
specially in the southern part oftheir range, but they may also occur in small streams,
elevated lakes, and 1ow ponds (McPhail and Lindsey 1970). In
Great Slave Lake, Canada, burbot are common at least to
depths of 100 m (Rawson 1951). Burbot in lakes have been
taken from as deep as 213 m and seem to be confined to the
hypo'limnion in summertime. River fish tend to congregate in
deep holes except during the spawning period (Morrow 1980).
Burbot were taken from Harding Lake, in interior Alaska, in
depths from 18 to 33 m in August (Doxey 1983).
Susitna River adult burbot ut'ilized deep eddies in the mainriver for summer habitat (ADF&G 1983a). After spawning,
burbot appeared to use the main river and, to a lesser
extent, the tributarjes for overwintering habitats. Burbot
were most often found in lower velocity backwater areas(0.0-1.0 ftlsec) but were observed in areas of higher
velocities (ibid.). Based on radio telemetry studies, most
Susitna burbot overwintered in the main river in areas having
relative'ly high specific conductances (above 200 umhos/cm)
and water temperatures (above 0.5"C), indicating areas with
an upward perco'lation of flow (ibid.).
Burbot spawn in streams or lake shallows under ice (McPhail
and Lindsey 1970). The spawning site is usually jn 0.3 to
1.3 m of water in shallow bays or on gravel shoals 1.5 to 3 m
deep (Scott and Crossman 1973). Sorokin (1971) reports that
burbot in the Lake Baikal system in southeast Siberia spawn
as far as possible upstream in ca'lm places where the depth
203
does not exceed L0 cm and the stream width was 30 cm. Lake
Baikal burbot spawned in areas with a weak current of
approximately 3 cm/sec, which turned the eggs and cleansed
them of silt (ibid. ).In Lake Mich'igan, high densities of burbot larvae were
collected within the 3 m bottom contour, indicating that
spawning may have occurred near shore (Mansfield et al.
1983). -However, because larvae are more buoyant than their
demersal eg9s, distribution of burbot larvae throughout the
water column in nearshore Lake Michigan demonstrates passive
dispersal by currents shortly after hatching (ib!d.).
3. Water temperature. Optimum temperatures for burbot range
ffiC with 23.3"c as the upper limit (scott and
Crossman 1973). The surface water temperatures during winter
spawning usually range from 0.6 to L.7oC (ibid.)' and in
tributai'ies of the Lake Baikal system, spawning occurs at 0"C
water temperature (Sorokin 1971). Burbot enter the Baikal
tributaries in the fa]1 when the water temperature drops to
10 to 12'C (ibid.).
Temperatures at which burbot eggs can deve'lop range from I to
7"C, and survival decreases rapidly when the temperature
deviates from 4oc (Jager et al. L979). Larvae beyond
metamorphosis survive'in water temperatures from 8 to 20oC,
and the larvae do not start feeding at temperatures lower
than 8oC (ibid.). Larvae in Lake Michigan were collected
most often in temperatures from 6 to Iz"C. However, larvae
are vulnerable to currents and may not be able to avoid less
preferred temperatures (Mansfield et al- 1983)-
4. Substrate. Scott and Crossman ( tgZS ) r.epo_rt that burbot
spawn over sand or grave'l bottoms in shallow bays or on
gravel shoals. Sorokin (1971) described the substrate of
burbot spawning areas as large cobble with a small amount of
silt, detritus, and organic debrjs. Burbot eggs are unable
to develop on soft, sitty bottoms (Volodin 1966). Burbot
larvae in Lake Michigan showed a preference for rocky sites
over sandy bottoms (Mansfield et al. 1983). Burbot in the
mainstem Susitna preferred areas with a rubble or cobble
substrate (Suchanek et al . 1984).
IV. NUTRITIONAL REQUIREMENTSA. Food Species Used
The burbot is an omnivorous carnivore. The diet of burbot varies
from place to p'lace, but most studies show that young burbot eat
mainly invertebr ates, whereas adults feed ma'in'ly on f ish (Bonde
and Maloney 1960, Clemens 1950a, Hewson 1955, Hanson and Qadri
1980, Chen- 1969). Young burbot in the Yukon and Tanana rivers
feed ma'in1y on i nsect I arvae, especi a'l 1y P'l ecoptera ,. Ephemerop-
tera, and -Diptera, and on slimy scu'lpins (Chen 1969). Q.y ages-
four to five', the burbot in Chen's study shifted to a diet of
fi sh.
204
V.
Adult burbot include a variety of fish in their diet. Burbot in
Harding Lake, in interior Alaska, consumed s_limy sculp.ins, least
ciscos, northern pike, burbot, and coho salmon (Hallberg 1'979,
Doxey igAg). In the Colville River of northern Alaska, burbot ate
slimy scuipins, n'inespine stickleback, round whitefish' and
grayi ing, ai wei 1 as snai I s, cadd'is f 'ly I arvae, and smal I mammal s
(ge-nOoc[ 1979). Burbot in Moose Lake, near G'lennallen' Alaska'
ite whitefish, burbot, and mollusks (Wittiams 1970), whereas Yukon
and Tanana river burbot jncluded slimy sculpin, burbot, lamprey,
round whitefish, 'longnose sucker, and northern pike in their diet
(Chen 1969). Arctic and least cisco were the primary food of
burbot inhabjtinq the coastal waters of the Yukon Territory'
Canada (Kenda'l et al. 1975). Adult burbot in the MacKenzie River
delta in Canada had a diverse diet, including a variety of
insects, crustaceans, sculpins, burbot, and smelt (Percy 1975).
B. Types of Feeding Areas Used
C-hbn (1969) siates that burbot are almost colpJete_ly bottom
feeders in the summer in the silty rivers he sampled. Chen found
that bottomfi sh domi nated the di et and noticed a frequent
occurrence of bottom debris and drowned shrews or mice in the
stomachs. Baily (I97?) also noted the presence in burbot stomachs
of rocks, wood chips, and plastic, which would indjcate
indiscriminate bottom feeding.
C. Factors Limiting the Availability of Food
Excessive sedifrentation may I imjt the production of aquatic
invertebrate fauna used especially by young burbot (Hall and McKay
1e83 ) .D. Feeding Behavior
McPhaii and Lindsey (1970) observed that burbot foraged actively
in dim light and wlre quiet in bright f ight. Moffow (1980) also
noted that burbot moved into shallow water to feed at night.
In the Great Lakes, burbot eat mainly fish during the winter and
shift to a diet of invertebrates in the surnmer (Bailey 1972,
Cl emens 1950a ) . However, fi sh compri se most of the stomach
contents of burbot in Alaska year-round (Chen 1969, Doxey 1983).
REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat
Burbot spawn in streams or lake shallows, usual'ly unde-r ice in
shallow water .3 to 3 m deep but sometimes 18 to 20 m deep
(McPhail and Lindsey 1970, Clemens 1950b, Scott ald Crossman
igZg). The spawning substrate is clean sand, grave'l , o.r large
cobbiestones witn oniy a small amount of silt or detritus (Sorokin
Lg71., Morrow 1980). Sorokin observed spawning in a stream with
partial ice cover, which was open in many places.
burbot in the Susitna River appeared to mj'll in preparation for
spawning in areas with an ice cover having low to medium (0.1-4.0
ftlsec)- water column velocjties (ADF&G 1983a). In areas of
riitin!, moderately high specific conductances (70-150 umhos/cm)
have been observed , suggesti ng that upwe'l 'l i ng may be occurri ng
205
B.
(ib.id.). Burbot spawn at Susitna tributary _mouths such as the
Deshka River and Alexander Creek, and radio te'lemetry data suggest
that burbot may also spawn in the mainstem (ADF&G 1983c).
Tributaries of Lake Michigan serve as spawning sites or nursery
areas for burbot (Mansfield et al. 1983). Rivers may provide
sources of food for young burbot, making spawning near river
mouths advantageous 1iUia. ). Juvenile burbot sampled in the
Susitna River were most numerous in sloughs and tributaries'
indicating that they were rearing near the -hatching area. (ADF&G
1983b). iuveniles were also found c'losely associated with the
ri ver bottom ( i bi d. ) .
Reproductive Seasonal ity
Thb burbot spawns from -t'lovember to May over the whole of its world
distribution'and mainly from January to March in Canada (Scott and
Crossman 1973) . Spawni ng i n the Lake Ba'i ka'l area occurs i n
January and February (Sorot<in 1971), and Chen (1969) also-reports
spawni-ng in the Yuk6n and Tanana rivers in these months. Spawning
ih tfre Susitna River below Devil Canyon occurs between mid January
and early February (ADF&G 1983d). In Harding Lake, in.interior
Alaska, -burbot slawning has been recorded 'in April (Ha'llberg
1e7e).
Reproductive Behavior
Male burbot reach the shallow spawning area first, fo'llowed in
three or four days by the females, and spawning occurs at.night
(Morrow 1980, Scott and Crossman 1973). However, samp-l ing i,t]^!n.
iusitna River indicates that females may arrive first (ADF&G
1g83c). Spawning takes place in a writh.ing ball about 2 ft in
diameier itrat mbves over the bottom ( ibjd. ). The eggs are
broadcast and then settle to the bottom. Sorokin (1971) notes
that the spawning streams in the Lake Baikal area are so shallow
that the fish are partly out of water during spawn'ing.
Age at Sexual MaturitY
Birbot mature from ag-es two to four jn the southern part of their
range but generally-not until they__rea_ch aggs six or Seven in
int6rior Aliska (Clien 1969). Colvitle River burbot reach sexual
maturity at age seven (Bendock 1979), whereas most burbot in Moose
Lake, near Gienallen, are sexual'ly mature by age five (Williams
and Potterville 1983). Clemens (1950b) found that growth of Lake
Erie burbot slowed down during the third and fourth years.and
increased afterwards. He exp'lained that this was due to their
reachi ng sexual maturi ty and chang'i.ng thei r f ood preference from
inverteSrates to fish. - Chen (1969) did not observe this growth
pattern in Alaskan fjsh.
Frequency of Breeding
Chen (tgOg) states that probably not a1'l burbot spawn every year;
it may take more than one year to store the nutrients necessary
for jonadal development. - Susjtna River burbot appear to be
nonco-nsecutive spawners (ADF&G 1983d).
c.
D.
E.
206
F. Fecundity
A 10-year-o1d female burbot from the Tanana River produced over
738,000 eggs (Chen 1969). An average adult female produces from
500;000 to- 750,000 eggs and occasionally as many as 1.5 million
(Momow 1980).G. Incubation Period/Emergence
Development time of burbot eggs varies with the temperature and
possibty with the popu'lation. At 6.1oC, hatching occurs in about
30 dayi, and at temperatures from 0 to 3.6oC about 7I days grq
needed (ibjd.). Chen (1969) concludes that the incubation period
of burbot eggs in the Tanana River, which has a water temperature
close to 0'C-in the winter, is probab'ly less than three months.
VI. MOVEMENTS ASSOCIATED t,'|ITH LIFE FUNCTIONS
During most of their I ife history, burbot are rather sedentary;
however, there appear to be definite movements toward spawning areas.
0bservaiions of' tagged burbot in the Susitna River indicate that
whereas burbot are ielative'ly sedentary, they are nevertheless capab'le
of long-distance movements. (ADF&G 1983b and c). One radio-tagged
burbot moved downstream approximately 60 mi in the winter and then held
its new position (ADF&G 1983b).
Generally, the spawning migration is ong of individual movements'
rather dfran of a'whole school' together (Morrow 1980). Lake Baikal
burbot move into the tributaries in the fall when the water temperature
drops (Sorokin 1971). This is initial'ly a feeding migration to the
lowbr reaches of the rivers. Slightly later, the burbot move farther
upstream for spawning. The prespawning migration to the tributaries is
bblieved to begin in mid September an.d last until mid January for
burbot in the Susitna River (ADF&G 1983d).
Sorokin (tgZt) observed a downstream migration to the lower reaches of
the rivers after spawning. A slight downstream.postspawning movement
was also observed in Sus'itna River burbot (ibid.). Burbot in Ontario'
however, have been observed to make postspawning runs upriver,
apparent'ly for feedi ng (MacCrimmon 1959) .
VII. FACTORS INFLUENCING POPULATIONSA. Natural
Burbot are prey to several species of fish, inc'lud'ing sme]t,
perch, lake trout, and northern pike (Scott and Crossman 1973,
Johnson t975, Hallberg 1979). Adult burbot are also known to feed
on smaller burbot (Witliams 1970, Chen 1969, Ha'llberg 1979).
Foxes sometimes take spawning burbot in shallow streams (Sorokin
le71 ) .
Immature burbot compete for food with other invertebrate-consuming
species (C'lemens 1950a). Adult burbot can consume large numbers
of fish and are potential competitors with other piscivorous fish
(Scott and Crossnian 1973, Bonde and Maloney 1960, Bailey 1972).
B. Human-rel ated
Any djsturbances within a system that degrade burbot spawning,
reiring, or feeding habitats, degrade water qua'lity, or.block
migration routes may adversely affect population levels of burbot
207
occuzu(i ng that system. A summary of possi b1e impacts from
human-related activities includes the following:o Alteration of preferred water tenperatures, pH,
dissolved oxygen, and chemical compositiono Alteration of preferred water velocity and deptho Alteration of preferred stream or lake morphologyo Increase in suspended organic or mineral materialo Increase in sedimentationo Reduction in food supplyo Shock waves in aquatic environmento Human harvest
(See the Impacts of Land and Water Use volume of this series for
additional information regarding impacts. )
VIII.LEGAL STATUS
The A'laska Department of Fi sh and
. managerial authority over burbot.
IX. LIMITATIONS OF INFORMATION
Game, Division of Sport Fish, has
The information collected on burbot in Alaska has concentrated on the
food habits and age structure of populations. As angler pressure
increases, especial'ly winter ice-fishing, many gaps in the knowledge
critical to management of this species become apparent. A better
understanding of early life h'istory, feeding and spawning habitats,
nursery areis , mi grat'iona'l patterns , competi ti on wi th other f i sh
species, and the effects of various habitat alterations is necessary.
REFERENCES
ADEC.. I979. Water qual ity standards, Alaska Water Pol lution Control
Program. Juneau. 34 pp.
ADF&G. 1978. Alaska's fisheries atlas. Vol.
K.J. Delaney, comps.]. Juneau. 43 pp. + maps.
. 1983a. Aquatic habitat and instream flow
-Hydro
Aquatic Studies. Phase II, basic
Anchorage. 398 pp.
. 1983b. Resident and juvenile anadromous fish studies on the
-
ltna River below Devil Canyon, 1982. Susitna Hydro Aquatic Studies.
Phase II, basic data rept. Vol.3. Anchorage. 277 pp.
. 1983c. Upper Susitna Rjver impoundment studies 1982. Susitna--Tydro Aquatic Studies. Phase II, basic data rept. Vol . 5.
Anchorage. 152 pp.
. 1983d. t,'linter aquatic studies, 0ctober 1982-May 1983. Susitna
--TtAro Aquatic Studies. Phase II, basic data rept. Anchorage. 137 pp.
2 [R. F. Mclean and
studies, 1982. Susitna
data rept. Vol. 4.
208
Bailey, M.M. 1972. Age, growth, reproduction' and food of the burbot' Lotaiota (Linnaeus), in sbuthwestern Lake Superior. Trans. Am. Fish. Soc.
frT:aat-Atq.
Bell, M.C. 1973. Fisheries handbook of engineering requirements and
biological criteria. Fisheries - engineering researci _p-rogram, Corps
of Engineers, North Pacific Div., Portland, 0R. Feb. 1973.
Bendock, T.N. I979. Inventory and cataloging of arctic area waters.
ADF&G, Fed. Aid in Fish. Rest. Ann performance rept. Vol. 20.
Job G-l-I.
Bonde, T., and J.E. MaloneY. 1960.
Fish. Soc. 89:374-376.
Food habits of burbot. Trans. Am.
Chen, Lo Chai. 1969. The biology and taxonomy of the burbot'
leptura. Univ. Alaska Bio'logical Papers No. 11. 53 pp.
Clemens, H.P. 1950a. The food of the burbot Lota lota lqqqlogain Lake Erie. Trans. Am. Fish. Soc.80:56--6'61
. 1950b. The growth of the burbot Lota lota maculosa (Le
-Ta-ne Erie. Trans. Am. Fish. Soc. 80:163-173.
Lota 'lota
(Le Sueur)
Sueur) in
Doxey, M. 1983. Population studies of game fish and evaluation of managed-lakes in the Salcha District with emphasis on Birch and Harding lakes.
ADF&G, Fed. Aid in Fish Rest. Ann. performance rept. Vol. 24.
Job G-III-K.
Hall, J.E., and D.0. McKay. 1983. The efforts of sedimentation on
salmonids and macro-invertebrates: a literature review. ADF&G, Div.
Habitat, Anchorage. Unpubl. rept. March 1983. 31 pp.
Ha'f1berg, J.E. 1979. Evaluation of management practices in four selected
lakes of jnterior Alaska. ADF&G, Fed. Aid in Fish Rest. Ann perfor-
mance rept. Vol. 20. Job G-III-J. 20 pp
Hanson, J.M., and S.U. Qadri. 1980. Morphology and diet of young-of-the-
year burbot, Lota lota in the 0ttawa Rjver. Can. Field-Nat.
94( 3) :311-314.
Hewson, L.C. 1955. Age, maturity, spawning, and food of burbot'
in Lake Winnipeg. J. Fish. Res. Bd. Can. 12(6):930-940.
Jager, T., tl|. Nellen, W. Schofer, and, F. Shodiai. _ 1979. Influence of- salinity and temperature on early life stages of Coregongs albula' C.
lavaretirs, R. ruitilus, and L. tbta. Pagei 345-34-Tfr'-R; Gsker anO
T.-Serman,?ds:-ThFear'ly ilte-hTitory of fish: receiT studies. ICES
Symposium on the early life history of fish, Woods Hole' Ma.2 Apr.
1979.
Lota I ota,
209
Johnson, L. 1975. Distribution of fish species in Great Bear Lake,
Noithwest Territories, with reference to zooplankton, benthic
jnvertebrates, and environmental conditions. J. Fish. Res. Bd. Can.
32(11):1'989-2,004.
Kendel, R.E., R.A.C. Johnston, U. Lobsiger, and M.D. Kozak. I975. Fishes
of the Yukon coast. Beaufort Sea Tech. Rept. No. 6. Beaufort Sea
Project, Dept. of the Environment, Victoria, B.C. 114 pp.
MacCpimmon, H.R. 1959. 0bservations on spawn'ing of burbot in Lake Simcoe'
Qntario. J. tl|ildl. Manage. 23(4)2447-449, Cited in Morrow 1980.
Mansfield, P.J., D.J. Jude, D.T. Michaud, D.C. Brazo, and J. Gulvas. 1983.
Djstribution and abundance of larval burbot and deepwater sculpin 'in
Lake Michigan. Trans. Am. Fish. Soc. II2:|62-L72.
McPhail, J.D., and C.C. Lindsey. 1970. Freshwater fishes of northwestern
Canada and Alaska. Fish. Res. Bd. Can. Bull. No. 173. 381 pp.
Morrow, J.E. 1980. The freshwater fishes of Alaska.
Northwes t Publ i s h'i ng Co. 248 PP .
Anchorage: Alaska
Peckham, R.D. 1979. Evaluat'ion of Interior Alaska waters and sport figh
with emphasis on managed waters - Delta District. ADF&G, Fed. Aid in
Fish Rest. Ann. performance rept. Vol . 20. Job G-III-1.
Percy, R. 1975. Fishes of the outer MacKenzie delta. Beaufort Sea Tech.-Rept. No. 8. Beaufort Sea Project, Dept. of the Environment, Victoria,
B"'C. 114 pp.
Rawson, D.S. 1951. Studies of fish of Great Slave Lake. J. Fish. Res. Bd.
Can. 8:207-240. Cited in McPhail and Lindsey 1970.
Scott, hl.B., and E.J. Crossman. 1973. Freshwater fishes of Canada. Fish
Res. Bd. Can. Bull. No. 184. 966 PP.
Sorokin, V.N. I97I. The spawning and spawning grounds of
lota. J. Ichthyology 11(6):907-915.
Suchanek, P., R. Sundet, and M. Wenger. 1984. Resident fish habitat
studies. Part 6 in ADF&G, Report No.2, resjdent and iuvenile
anadromous fish investigations, May-October 1983. Susitna Hydro
Aquat'i c Stud i es , Anchorage .
Vo'lodin, V.M. 1966. Burbot spawning grounds in Rybinsk reservoir. Tr.
Inst. B'iol., Vodokhraniljshch, 10(13). Cited in Sorokin 1971.
Williams, F.T. 1970. Inventory and cataloging of sport fish and sport fish
waters of the Copper Rivei and Prince hlilliam Sound drainages and the
the burbot Lota
2r0
Upper Susitna River. ADF&G, Fed. Aid in Fish Rest. Ann. rept.
Vol. 11. Proi. F'9-2, Job 14-A.
williams, F.T., and hl.D. Potterville. 1983. Inventory and-catalogi.ng.of
iprit fish inO sport fish waters of the Copper--t11..,- P.rince William
Sbund, and the upper Susitna River drainages. ADF&G, Fed. Aid in Fish
Rest. Ann. perfdrmance rept. Vol . 24. Proi. F-9-15' Job G-I-F.
2LT
I.
II.
Iahe Tfout Life History and Habitat Requirements
Southcentral Alasha
Map 1. Range of lake trout (Morrow 1980)
NAMEA. Comnnon Name: Lake troutB. Scientjfic Name: Salve'linus namaycush (Walbaum)
LaketroutarenotffiSalmo);mostichthyo1ogists
place them in the genus Salvelinus to ernphasize their close rela-
tionship to other ciar (llcmelT ana Lindsey 1970).
RANGEA. Statewide
Lake trout are distributed throughout highland lakes of the Brooks
Range, the Arctic coastal p'lain, Bristol Bay, and the Kenai and
upper Susitna and Copper river drainages (ADF&G 1978b). They are
generally absent from lakes of the Northslope'low1ands and the
lower Yukon-Kuskokwim river basins (Morrow 1980, McPhail and
ilil|ilrll
<?Y
i" o j .DdpJbo
2t3
Lindsey 1970) and are not found jn the Wood River.system or in
A]aska-Peninsula systems south of Mother Goose Lake (Alt 1977).
B. Reg{ ona'l Di stri buti on Summary
To supplement the distribution information presented in the text,
a series of bluelined reference maps has been prepared for each
region. llost of the maps in this series are at 1:250,000 _scale,bul some are at 1:].,000,000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition,
a set of colored 1:1,000,000-scale index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.
1. Southcentral. Lake trout are most abundant in the upper
ffiand-Copper river drainages, occurring in most large
area lakes and some smaller ones (e.g., Lake Louise, Paxon,
Crosswind, Fie'lding, and Susitna lakes and Klutina Lake and
River). They are found in several lakes on the Kenai
Peninsula (e.g., Tustumena, Skilak, Hidden, Swan, Juneau, and
Kenai lakes; a'lso Trail Lake and River). They also occur in
a few lakes on the west sjde of Cook Inlet (e.9., Chelatna,
Chakachamna, and Beluga lakes) and in the Matanuska Va11ey
(e.g., Byers and Lucy lakes). In the Cordova area' Little
Tokun Lake near Bering Glacjer contains the onl.y known
population (ADF&G I976, 1978a, 1978b; Redick 1970). (For
more deta'iled narrative information, see volume ? of the
Alaska Habitat Management Guide for the Southcentral Region.)
III. PHYSICAL HABITAT REQUIREMENTSA, Aquat'ic
1 . Water qual i tY:a. Temperature. Lake trout can tolerate only a narrow
fange o-temperatures , general 'ly i nhab'iti ng waters wi th
temperatures rangi ng between 4.4 and 10"C i n the
shallows during winter and in deeper waters below the
thermocline during summer (Alt 1977, ADF&G 1978b, Rawson
1961 ) . The upper I imi t of preferred temperature i s
reported to be 7?."C (Ferguson 1958). . 0ptimum spawning
temperature is 8.8 to 10'C (ADF&G 1978).b. The pH factor. Litt'le information was found in theTiffin-the jnfluence of pH levels on the survival
and development of lake trout. hlaters of the western
North Slope inhabitated by lake trout, among many other
species of fish, are characteristically soft, having, 'low
values for alkalin'ity and hardness and a neutral pH
(Bendock 1979).
Experimental studies conducted in Whitepine Lake near
Sudbury, Canada, indicate that under natural conditions
most lake trout sac fry could tolerate short periods of
substantial pH depression (five da-vs at pH less than
214
c.
5.0), though they show obvious signs. of stress under
theie conditions (Gunn and Keller 1984).
Dissolved oxygen (D.0.). No informat'ion was found on
ffiissolved oxygen levels on the survival
and development of lake trout in Alaska. Studies
examining tfre eutrophication (increased s.uspension of
phytoplaikton and deiritus) of the Great Lakes concluded
lnit,'especially during periods of thermal stratifica-
tion, oxidation of organic matter can cause widespread
2.
3.
hypolimnetic oxygen dep'letion, whjch is probably detri-
menta'l to this species; no minimum concentrations were
reported, however (Leach and Nepszy 1976).
d. tui^Ui a.ity. Turb j di ty_ and resul tant sedimentati on from
eiTnffiAnoff material or eutrophication could degrade
inshore spawning areas used by. lake trout (jbid.).
e. Salinity. Boulva and Simard (1968) found lake trout to
Ee Tnb-Teast tolerant of salt water of all the chars and
reported that the upper limjt of salinity tolerance
apilears to be around 11-13 parts per thousand.
Water qiranti ty. Lake trout requ'i re l akes 'large enough a!d
d-eepTfiougfi-$ therma]1y stratify during periods of hot, calm
weather. -They prefer the cooler water below the thermocline.
Rawson (1961i iound that lake trout required depths of.-1!
least 15 and usually 20 m jn Lac La Ronge, Saskatchewan (55"
north latitude) during the months of Ju'ly and August.
Substrate. Spawning iypical'ly occurs over a clean, rocky, or
Fu55le E,ottom'(Morrow 1ggo, ADF&G 1978b, Rawson 1961).
B. Terrestrial
Protective cover is provided for adults by deep poo'ls and swjft
riffles in rivers and somet'imes by undeicut banks (Alt 1977).
Rocky bottom areas in lakes provide cover from .predation for
juveniles. They may spend several years hiding'in the rubble of a
lake bottom (Alt 1977, ADF&G 1978b).
IV. NUTRITIONAL REQUIREMENTSA. Food Species Used
Preferi^ed foods vary with the age and size of the fish and in
response to availaUitity. Juvenile lake trout feed on small
crustaceans, particularly Mysis relicta, when present, plankton,
detrius, insect (Diptera)-Tarvae, affi some small fish (Morrow
1980, ADF&G 1978b, Redick 1970). As lake trout mature, they beg'in
to eat more fish and fewer invertebrates; some feed on plankton
throughout their I ives (Martin .|966). Preferred foods 'include
fi sh -(Coregonids, sf imy scul pi n ICottus cognatus Richardson],
ninespine -stickieback - [Pungjtius @nnaeus]-, anq
juvenile salmon), snails,-DTpffi lirvEell-lant material , and
small mammals (voles) (Alt 1977, 1978, Bendock L979, Morrow 1980,
Redick 1970, Scott and Crossman 1973). Lake trout popu'lations in
systems wheie forage fish are not available do not grow as large
215
as those that feed on fish (Martin .|966, Sautner and Stratton
I e84).B. Types of Feeding Areas Used
Juvenile lake trout may spend several years near the bottom'
seeking protection from predators and feeding. In the spring'
older lake trout feed inshore and near the surface. As the water
temperatures in the lakes rise, lake trout move deeper and finally
reside beneath the thermocline (Redick 1970). Lake trout were
generally more abundant near inlet and outlet streams of lakes
studied in the lower Kuskokwim River and Kuskokwim Bay area in
Ju'ly 1978, because of cooler water temperatures and greater food
abundance (Alt 1977).C. Factors Limiting Availability of Food
Nutrient loading, or eutrophication, of a system leads to changes
in the qua'l'ity and species types of phytoplankton, zooplankton,
and benthic organisms available to 'lake trout (Leach and Nepsky
1976). Excessive sedimentation may inhibit production of aquatic
invertebrate fauna (Hall and McKay 1983).
During periods of thermal stratjfication, lake trout are
restricted to food items available below the thermal barrier
(Scott and Crossman 1973).D. Feeding Behavior
Lake tiout are opportunistic feeders able to take advantage of an
abundance of almost any food; they are part'icul arly vorac'ious in
the spring (ibid. ).
V. REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat
Most lake trout are lake spawners, but river-spawning populations
are known to exist. Spawn'ing typically occurs on reefs or shoal
areas at depths of less than 12 m (a0 ft) but sometimes in depths
of less than a meter to as deep as 61 m (200 ft) (Morrow 1980'
ADF&G 1978b, Redick 1970) . Red'ick ( 1970) reported that al I
spawning in Susitna Lake appeared to occur between depths of from
2 to 5 m. Spawning sites are often associated w'ith windy.qry?!
because of the water movements produced by wave action (ADF&G
1e78b).B. Reproductive Seasonal ity
Generally, lake trout spawn in late surnmer and early autumn,
depending on latitude,, water temperature, and the s'ize and
elbvatioi of the 'lake (ADF&G 1978b, Scott and Crossman 1973).
Spawning occurs as early as late August and early Septembelin
northern Alaska (McCart et al. L972) to as late as November in
Canada (Scott and Crossman 1973).C. Reproductive Behavior
Maies typica'l 1y reach the spawning grounds first, select the
spawning'site, and then prepare jt by brushing the mud and silt
oif the-rocks with their body or tail fin or by rubbing them with
their snouts. They do not dig a redd. A group of several males
may clean an area-of several-dozen square meters (Martin 1957).
2r6
D.
Females arrive a few days after the males. One or two males may
spawn with one female or a group of males and females may spawn in
masS, broadcasting eggs and sperm over the bottom to settle into
crevices between rocks. The spawning act may be repeated many
tjmes before a female has vojded her eggs (Morrow 1980, Scott and
Crossman 1973).
Lake trout reproductive studies conducted in New York and Ontario
found that spawning activity occurred only at night. During the
day, the fish were dispersed but returned to the spawning beds'in
great numbers, with peak activity occuming between dusk and 9 or
iO p.t'1. (Royce 1951, Martin 1957). No information on circadian
spawning activity jn Alaskan waters was found in the avajlable
I i terature.
Age at Sexual Maturity
Lake trout are slow-growing and late-maturing. Sexual maturity is
more closely correlated with size than with age; however, it is
usual'ly attained by ages V to VII but may not be achieved until as
late as age XIII (Morrow 1980, ADF&G 1978b, Scott and Crossman
1973). In the lower Kuskokwjm River and Kuskokwim Bay area'
sexual maturity is not reached until ages VIII to XI (A'lt I977),
Males usually mature a year earlier than females (Morrow 1980).
Longevi ty of I ake trout 'is vari abl e , wi th the o'ldest on record
estimatei to be 42+ from Chandler Lake, Alaska (Furniss L974).
Most individuals caught in the lower Kuskokwim River/Kuskokw'im Bay
area are 9 to 11 years old (Alt 1977). Alf (1977) also reports
that the growth of lake trout from the Kuskokwim study area is
general'ly slower than that reported from other waters in Interior
Alaska and Great Slave Lake in Canada but more rapid than growth
of lake trout in lakes of the Brooks Range, Alaska, and Great Bear
Lake, Northwest Territories. Lake trout from the Kuskokwim area
of Al as ka genera'l 1y do not I i ve as 1 ong as s1 ower-growi ng
populations in northern Alaska and Great Bear Lake (jbid.).
Frequency of Breeding
Spawn'ing frequency may vary from annual'ly to about once in three
ybars, but most iauti lake trout spawn every other year (Morrow
1980, ADF&G 1978b, Rawson 1961)
Fecundi ty
Fecundity varies with the sjze and condition of the female and may
range from a few hundred up to 18,000 eggs (Morrow 1980, ADF&G
1978b, Scott and Crossman 1973).
Incubati on Peri od/Emergence
Incubation requires 15 to ?I weeks or more, depend'ing on water
temperature; and alevins (yo1k-sac fry) usually hatch in mid Feb-
ruary or late March (Eschmeyer 1955, Martin 1957). The alevins
remain in the cover of the rocky substrate approximately a month
until their yolk sac is absorbed; then the newly emerged fry move
away from the spawning areas and into deeper water (Morrow 1980'
Scott and Crossman 1973).
E.
F.
G.
217
VI. MOVEMENTS ASSOCIATED WITH LIFE FUNCTIONS
Whole popu,lations of lake trout do not undertake movements in definite
directions; they are solitary wanderers that move freely througho-ut
lakes between seasonal feeding areas and spawning grounds' limited in
movement ch'ief'ly by the size of the body of water (Morrow 1980' Scott
and Crossman 1973). Larger fish tend to travel greater distances
(Morrow 1980).
Depth distribution and seasonal movements of lake trout are p_rimarily
reiated to changing water temperatures. Lake trout typica'l1y move
into shallow water in the spring during ice break-up and remain there
until the surface water warms to above 10"C. As surface waters
approach 10oC, lake trout tend to move to cooler (deeper) waters,
evbntually congregating below the thermocline during the summer months,
preferring tempeiatures between 4.4"C anq 10oC (Martin 1952, ADF&G
1978b, Rawson 1961, Scott and Crossman 1973).In the fa't 1 , when cool ing surface waters destroy the thermal
strat'ification, lake trout return to the rocky shallows to spawn.' There is evidence of homing to prior spawning grounds (Martin
1960, Rawson 1961). After spawning, lake trout disperse
throughout the I ake at various depths and remai n d!spersed
throughout the wi nter months ( Rawson 1961 , Scott and Crossman
1e73).
VII. FACTORS INFLUENCING POPULATIONSA. Natural
A low water table and cold winter temperatures could cause eggs
deposjted at lake margins to desiccate or to freeze. High water
temperatures (above 10"C) and resultant deep heating during_the
summer could be detrimental to lake trout. 0ccasional'ly, lake
trout become cannibaf istic, eating their own eggs and young.
Small lake trout are also preyed upon by burbot and northern pike
(Redick 1970). Round whitefish have been reported consum'ing eggs
of river-spawning lake trout (Loftus 1958), and burbot are
reported to eat lake trout eggs (Anon. 1960).B. Human-rel ated
Freshwater habitat is critical to lake trout populations. Each
system is a semiconfined environment jn which the populaliqn
slends all life phases, including the most sens'itive life
firnctions of spawning, rearing of young, and feeding. These
activities frequent'ly are undertaken in djfferent locations within
a lake or tributary or outlet stream and therefore require move-
ment within the system. Disturbances that degrade lake trout
spawning, rearing, or feeding habitats, degrade water qua'li!y, or
block fjsh migration routes may adversely affect the population
levels of lake trout that use the disturbed system.A sumnary of possib'le impacts from human-related activities
i ncl udes the fol 'lowi ng :o Alteratjon of preferred water temperatures, pH, dissolved
oxygen, and chemjcal compositiono Alterat'ion of preferred water velocity and depth
?TB
" Alteration of preferred lake/stream morphologyo Increase in suspended organic or mineral material
" Increase in sedimentation and reduction in permeabi'lity of
substrateo Reductjon in food suPPlYo Reduction in protect'ive covero Shock waves in aquat'ic environment
" Human harvest
(See the Impacts of Land and Water Use volume of thjs series for
additional information regarding impacts. )
VIII. LEGAL STATUS
The Alaska Department of Fish and Game, Division of Sport Fish, has
managerial authority over Iake trout.
IX. LIMITATIONS OF INFORMATION
Most of the information available on lake trout has been collected in
Canada and the Great Lakes regioni very little ljfe history information
specific to Alaska has been collected. There are major gaps .in.oYr
knowledge critical to the future management of lake trout and their
habi tat. lrlo i nformati on was found i n the I i terature rel ati ng the
various lake trout life stages to the chemical characteristics of their
habitats. Little information was found on the effects of environmental
changes. A better understanding of popu'lation dynamics, feed'ing
habits, and river-spawning populatjons is necessary.
RE FERENCES
ADF&G, comp. L976. A fish and wildlife resource inventory of the Cook In-
let-Kodiak areas. Vol. 2: Fisheries. Juneau. 434 pp.
. 1978a. A fish and wildlife resource inventory of the Prince---l'TTt i am Sound area. Vol . 2: Fi sheries. Juneau . 24L pp.
ADF&G. 1978b. Alaska's fisheries atlas. Vol. 2 [R.F. Mclean and
K.J. De'laney, comps.]. 43 pp. + maps
Alt, K.T. 1977. Inventory and cataloging of sport fish and sport fish
waters of Western Alaska. ADF&G, Fed. Aid in Fish Rest. Ann. perfor-
mance rept. Vol. 18. Proi. F-9-9, Job G-I-P.
. 1978. Inventory and cataloging of sport fish and sport fish
----Ta-ters of Western Alaska. ADF&G, Fed. Aid in Fish Rest. Ann.
performance rept. Vol. 19. Proj. F-9-10, Job G-l-P.
Anon. 1960. Maria eat eggs. Fishing. Fish. Br. Prov. Manitoba 1(4):13.
Cited in Scott and Crossman 1973.
2L9
Bendock, T.N, !979. Inventory and cataloging of arctic _area waters.
ADF&G, fud. Aid in Fish Rest. Ann. performance rept. Vol . 20. Pttoi.
F-9-11, Job G-I-I.
Boulva, J., and A. simard. 1968. Presence due Salvefugg !aTqy,gYsl(pirl.i: Satmonidae) dans les eaux marine de rffiique oETd-Efr'[aT
ianadian. J. Fish. Res. Bd. Can. 25(7):l',501-1,504.
Eschmeyer, P.H. 1955. The reproduction of lake trout in southern Lake
Superior. Trans. Am. Fish. Soc. 84:47-74. Cited in Morrow 1980.
Ferguson, R.G. 1958. The preferred temperature of fjsh and their midsurnmer- disiribution in temperate lakes and streams. J. F'ish Res. Bd. Can.
15:607 -624.
Furniss, R.A. 1,974. Inventory and cataloging of arctic area waters.
ADF&G, Fed. Aid in Fish Rest. Ann. performance rept. Vol. 15. Proi.' F-9-5, Job G-I-I. Cited in Morrow 1980.
Gunn, J.M., and hl. Keller. 1984. Spawning site water chemist_ry and lake
trout (Salvelinus namaycvs.h) sac fry surviva'l during snowmelt. Can. J.
Fish. AqGffi4I:3IETg.
Ha'11, J.E., and D.0. McKay. 1983. The effects of sedimentation on'salmonids and macoo-jnvertebrates: a literature review. ADF&G, Div.
Habitat, unpubl. rept. 31 PP.
Leach, J.H., and S.J. NePszY. 1"976.
J. Fish Res. Bd. Can. 33:622'638.
The fish community in Lake Erie.
Loftus, K.H. 1958. Studjes on river spawning popu'latjons qf lake trout'in
eastern Lake Superior. Trans. Am. Fish. Soc. 87:259-277.
McCart, P., P. Craig, and H. Bain. 1972. Report on fjsheries jnvestigations
in ttre Sagavanirktok River and neighboring drainages. A'lyeska P'ipeline
Service Company. 170 PP.
Mcphail, J.D. and C.C. Lindsey. 1970. Freshwater fishes of northwestern
Canada and Alaska. Bull. Fish. Res. Bd. Can. I73. 381 pp.
Martin, N.V. 1952.
Algonquin Park,
Martin, N.V. 1957.
Trans. Am. Fish
Morrow 1980.
A study of the lake trout, Salvelinus lamaycu:hr in two
0ntari"o, I akes. Trans. Am.-FTih'-Ec. mTn:T37.
Reproduction of lake trout in Algonquin Park,0ntario.
Sbc. 86:231-244. Cited in Scott and Crossman L973,
. 1960. Homing behavior in spawning lake trout. Canada Fish Cult.--3:s-0.
220
. .|966. The significance of food habits in th_e biology,
-- exptoitation, and management of Algonqrlil Park, Ontario, lake trout.
Trirns. Am. Fish. Soc. 95:415-422. Cited'in Scott and Crossman .|973.
Morrow, J.E. 1980. The freshwater fishes of Alaska. Anchorage, AK: Alaska
Northwest Publishing Company. 248 pp.
Rawson, D.S. 1961. The lake trout of Lac La Ronge, Saskatchewan. J. Fish.
Res. Bd. Can. 18(3):423-462.
Redjck, R.R. 1970. The lake trout in Alaska.
Series, Fishes: N0.3.
ADF&G, l.lildlife Notebook
Royce, l|l.F. 1951. Breeding habits of lake trout jn New York.
52(59):59-76.
USFt,lS Bul l.
Sautner, J.S., and M.E. Stratton. 1984. Access and transmjssion corridor
studies. Part 1 in D.C. Schmidt, C.C. Estes,0.L. Crawford, and
D.S. Vincent-Lan9, 6ii-s. ADF&G Susitna Hydro Aquatic Studjes._ Rept.,4:
Access and transmission corridor aquatic investigations (Ju1y-October
le83).
Scott, W.8., and E.J. Crossman. 1973. Freshwater fishes of Canada. Bull.
Fish. Res. Bd. Can. 184. 965 PP.
22r
I.
II.
Rainbow Ttout/Steelhead Tlout
Life History and Habitat Requirements
Southrest and Southcentral Alasha
..7Pn;
Map 1. Range of rainbow trout/steelhead trout (ADF&G 1978)
NAMEA. Common Names: Rainbow trout and steelhead troutB. Scientific Name: Salmo gairdneri
RANGEA. Statewide
Rainbow trout are found throughout Southeast Alaska, west to the
Alaska Peninsula, and up the Kuskokwim River as far as Sleetmute
(ADF&G 1978).
Steelhead are found throughout Southeast Alaska, in the CopperRiver drainage, on the lower Kenai Peninsula as far up as the
Kasilof River, on Kodiak Island, and on the Alaska Peninsu'la.
= 9teelhead
a 'ao " j 'od7J';o
223
B.Reg'iona1 Di stri bution SurnmarY
To'supplement the distribution 'information presented in the text,
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale,
bul some are at 1:1,000,000 scale. These maps are avai]able for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsib'le for their reproduction. In addition'
a set of colored 1:i,000,000-sca1e index maps of selected fish and
wildljfe species has been prepared and may be found in the Atlas
that accompanies each regional guide.
1. Southwest. Native rainbow trout are found on Kodiak Island.
Somilil ttre more important Kodiak rivers are Kar'luk,
Ayakulik, Portage, and Afognak. Native rainbow trout are
aiso found in gristo1 Bay drainages north of Becharof Lake
and the Egegik River to the Kuskokwim R'iver (ibid.). Largest
trout are iound in most lake-river systems, such as the
Naknek, Kvichak, and Alagnak (ibid.).
Stee|head trout are also native to Kod'iak Island, where they
are most abundant in the Karluk and Ayakulik rivers (Murray,
pers. comm.). steelhead are also found in a few streams on
Itre north side of the Alaska Peninsula, jncluding the Sandy
Rjver, Bear River, King salmon River, and steelhead creek.
0n the south side of the peninsula, steelhead have been
documented in the Chignjk River and a stream that drains into
Ivan Bay (ADF&G 1984) . ( For more detai I ed narrative
information, see volume I of the Alaska Habitat Management
Gujde for the Southwest Reg'ion. )2. Southcentral. Nat'ive rainbow trout are found in most
dFa-inages-o't the northern and western Kenai Peni nsul a, f rom
Anchor- River north to the chickaloon R'iver (ADF&G 1978).
They are found in the lower Susitna River drainage, and, to a
lesler extent, the Matanuska drainage and some of the larger
rivers flowing into northwestern Cook Inlet. Rainbows are
also found in some clearwater tributarjes of the copper
River, most importantly the Gul kana River ( ibid- ). - In
addition to native fjsh, several lakes in Southcentral Alaska
are stocked with rajnbow trout on a put-and-take basis.
Steelhead trout are found in several Kenai Peninsula streams
between Homer and the Kasilof River (jbid.). They are also
found in the copper River drainage, especial ly the Gu_'lkana
River (ibid.). 'steelhead trout in the Middle Fork of the
Gulkana River may be the northernmost natural steelhead
population in Aliska (wlttiams, pers.- comm.). (For -fmoreitetailed narrative information, see volume 2 of the Alaska
Habitat Management Guide for the Southcentral Region.)
224
III. PHYSICAL HABITAT REQUIREMTNTSA. Aquatic
I . Water qual ity:a. Temperature. Preferred temperatures for rainbow trout
Fo'm-F temry and wi'ld populations in the Great Lakes,
0ntario, and New York State have been reported to be
between 11.3 and 20"C (McCauley et al. 1977, McCau'ley
and Pond !971, Cherry et al. 1977). Upper lethal
temperatures for Great Lakes and New York rainbow were
25 to 26"C (Bigood and Berst 1969, Hokanson et al. 1977,
Cherry et al. 1977). The lower lethal temperature is
0"C (McAfee 1966).
Russell (1977) reported that rainbow spawning in Talarik
Creek (tributary to Lake Iliamna in Southwest Alaska)
peaked at 5 to 7"C and terminated at 7 to l6'C. Alljn
and Baxter (1957) observed rainbow spawning in
Cottonwood Creek (drainage of l,Jasilla Lake in
Southcentral Alaska) at temperatures of 6.7 to 7.8oC.
McAfee ( 1966) found increased mortal ity in rainbow
embryos at temperatures less than 7"C and normal
development at temperatures between 7 and 12"C.
Jones (1972) reported temperatures for the adul t
steel head spawning migration to be 2 to 6oC in
Petersburg Creek in Southeast Alaska. In 1973, however,
temperatures were 0 to 4oC, and he stated that
temperature did not appear to affect in-migration (Jones
1e73).
Sutherland (1973) reported that the limits of steelhead
di stri buti on 'i n the open ocean conform to the 5oC
isotherm in the north and the 15'C isotherm in the
south.b. The pH factor. Rainbow trout have been found to
;mlmtte to-- pH from 5.8 to 9.8 (McAfee 1966, Murray and
Ziebell 1984); however, acclimization to pH levels above
8.5 must take place gradulaly (over at least four days)
(Murray and Zjebell 1984).c. Dissolved oxygen (D.0.). Optimal oxygen levels for
y Ralejgh and Hickman (1982) to
be 7 mg/l or greater at temperatures less than 15'C and9 mg/l or greater at temperatures higher than 15oC.
State of Alaska water quality standards for growth and
propagation of fish require D.0. levels greater than 7
ms/l (ADEC 1979).
Lethal levels of D.0. reported for adults and iuveniles
range from 2.9 mg/l at 10 to 20'C (Downing and Merkens
1957) to 0.5 to 1.5 mg/l at 15"C (Streltsova 1964).
Raleigh and Hickman (1982) state that the lethal level
is approximately 3 mg/l.
Phi 1 1 i ps and Campbe'l I ( 1962) found that steel head
embryos from 0regon did not survive at D.0. levels of
225
7.2 rng/l or less. Silver et al. (1963) found that
steel head eggs from an Oregon hatchery survived to
hatching at D.0. levels as low as 2.6 ng/\ but that the
time to hatching increased from a mean of 36 days at
L1.2 mg/1 to a mean of 44 days at 2.6 mg/1 (at a water
velocity of 6 cm/hr). Shumway et al. (1964) also found
an increase of hatching time and a decrease in weight of
new'ly hatched fry at decreased D.0. I evel s (from
approx'imately 11 *g/l down to approximately 3 mg/l ).
Fry that are small and have taken long to develop may
not be viable in the natural environment.
Turbi di ty. H j gh I evel s of turb'i d'i ty may abrade and c'logTlffiiTIs, reduce feeding, and cause fish to avoid some
areas (Reiser and Bjornn L979). Turbidity and sedjmen-
tat'ion may smother food organisms and reduce primary
productivity (Bell 1973). Turbid water will absorb more
solar radjatjon than clear water and may thus indirect'ly
erect thermal barriers to migration (Reiser and Biornn
1979). Studjes of rainbow trout habitat in the Susitna
River indicate that rainbow trout genera'l'ly avoid turbid
water. However, when no other form of protective cover
is avai'lable, the trout apparently use the turbid water
for cover (Suchanek et al. 1984).
Kramer and Smith (1965) found that suspended wood fiber
at concentrations as low as 60 ppm (the lowest level
studied) caused signifjcant sublethal stress to rainbow
trout juveniles. Responses to suspended fiber included
reduced breath'ing rate, heart rate, respiration rate'
and growth rate. Fiber clogged buccal and gi1'l cavit'ies
and lilled a h'igh proport'ion (up to 100% at 250 ppm) of
alevins within 48 hours of hatching (Kramer and Smjth
1965). Excess turbidity from organic materials in the
process of oxidation may reduce oxygen below acceptable
levels (Bell 1973).
2.Water quantity. In the Susitna River, adult rainbow trout
d.
wAneffilll caught by boat electrofishing in areas with
water velocities less than 46 cm/sec (Suchanek et al. 1984).
Hook and 'line sampling 'indjcated that ra jnbow trout preferred
pools with velocities less than 15 cm/sec and depths greater
than 0.6 m (ibid. ). During spawning, stream velocity
influences the ease with which bottom materials are moved for
redd excavation and affects the energy expenditure required
for a spawner to maintain position above the redd site
(Russell 1977). Sufficient water ve'locity and depth are
needed to allow proper intragravel water movement so that
di ssol ved oxygen i s transported to eggs and al evi n and
metabolic wastes are removed (Rejser and Bjornn 1979). Smith
(1973) gave depth and velocity requ'irements for spawning
steelhead in 0regon as at least 0.24 m deep and 40 to 91
cm/sec. Ra'inbow trout values were at least 0.18 m deep and
226
3.
48 to 91 cm/sec. Alljn and Baxter (1957) noted that spawning
rainbow trout prefer water .1 to .25 m deep with a moderately
swift velocity (less than I.2 m/sec) in Cottonwood Creek,
Alaska. Jones (1975) found that spawning steelhead in
Petersburg Creek in Southeast Alaska favored water 0.2 to
0.35 m deep but that they were also found spawning on shallow
riffles not exceeding 0.16 m in depth. In Lower Talarik
Creek (draining into Lake Iliamna, Alaska), rainbow trout
redds are located in areas where stream velocities are 30 to
60 cmlsec (Russel 1 1977).l^lithler ( 1966) noted that temporary high-water flows
(freshets) ma.y be necessary to jnitiate upstream movement of
spawning stee'lhead jn British Columbia. Jones (1973) _alsonoted that water level is the most important factor influen-
cing immigrating steelhead in Petersburg Creek' Alaska.
Steel head moved upstream most readi'ly on ri s'ing stream
levels.
Steelhead and rainbow fry in streams are found in shallower
water and slower velocities than at other life stages (Miller
Ig57 , Horner and Bjornn 1976). Everest and Chapman (I972)
found underyearling steelhead in an Idaho stream in water
less than 0.5 m in depth and of less than 0.3 m/sec velocity.
Age 1+ steelhead werein water greater than 0.9 m jn depth
and of greater than 0.5 m/sec velocity. Jones (tglZ) stated
that the most favored rearing habitat type in Petersburg
Creek, Alaska, is a stream section 0.15 to 0.60 m deep with
moderate-to-fast flow (no actual velocity measurements were
taken ) .
Substrate. In the Susjtna River, adult rainbow trout use
rotks wTth diameters over 8 cm for cover (Suchanek et al.
1984). The substrate composition of salmonid spawning beds
influences the development and emergence of fry. Substrates
with low permeability result in lower apparent velocities and
reduced oxygen delivery to, and metaboljte removal from, eggs
(Reiser and Bjornn 1979). Successful fry emergence is also
hindered by excessive amounts of sand and silt in the gravel
(ibid.).
Phillips et al. (tgZS) found that emergent surv'ival of
steelhead alevins from an 0regon stream was on'ly 18% in a
substrate mixture of 70% sand (1ess than 3.3 nm djameter)n
compared to 94% surv'ival in the control substrate with no
sand. McCuddin (1977) reported that survival and emergence
of steelhead embryos was reduced when sediments less than 6.4
mm in diameter made up 20 to 25% or more of the substrate.
Jones ( 1975) found that steel head i n Petersburg Creek,
Alaska, generally select redd sites in areas with gravel 5 to
10 cm in diameter; however, some redds were in areas
comprised of fine gravel (1ess than 5 cm) and in areas of
large cobble and boulders. Allin and Baxter (1957) observed
that rainbow trout in Cottonwood Creek in Southcentral Alaska
227
prefer to spawn on gravel loose enough for digging to a depth
of 10 to 13 cm. Gravel taken from one Cottonwood Creek redd
consisted of 72% particles greater than .85 cm in diameter.
Large substrate is important as cover for overuintering
steilhead fry in streams. Bustard and Narver (1975) found
that rubble in the 10 to 25 cm range was used as cover by
over 50% of age 0 steelhead fry overwintering in a Vancouver
Island stream. In streams where larger substrate is avail-
able, overw'intering steelhead fry may be associated with
rubble 20 to 40 cm or larger (Everest 1969, Hartman 1965).
H'i di ng i n rubbl e i n the wi nter reduces downstream
displacement during freshets and probably also is a means of
avoi di ng predati on i n wi nter, when swimmi ng abi 1 i ty i s
reduced (Bustard and Narver 1975).
Substrate sjze also influences stream invertebrate popula-
tions, which are 'important as the food source of rearing. salmonids. Reiser and Bjornn ( 1979) stated that highest
invertebrate production is from areas with grave'l and rubble-
size material s.B. Terrestrial
Protective cover is provided by overhanging vegetation and under-
cut banks (in addition to instream cover provided by such factors
as rocks, submerged 1 ogs, and turbulent water) (Giger 1973,
Suchanek et al. 1984). Nearness of cover may be important to fish
waiting to spawn, as spawning often takes p'lace in open segments
of streams where fish are vulnerable to disturbance and predation
(Reiser and Bjornn 1979). Jones (1976) noted that adequate cover
to escape predat'ion is the most important factor in redd site
sel ecti on i n smal I tri butary streams of Petersburg Creek i n
Southeast Alaska.
IV. NUTRITIONAL REQUIREMENTSA. Food Species Used
Rainbow and steelhead are largely opportunistic feeders, consuming
whatever is available jn their environment (Morrow 1980).
Generally, those in fresh water feed on insects (especially larval
and adu11 dipterans) and crustaceans (such as Gammarus) (ibid.).
Large adult rainbows eat other fjshes (ibid.). In the open ocean'
steelhead feed on squid, amphipods, and green'ling (Hexagramm'idae)
(Sheppard t972).Allin and Baxter (1957) found that 75% of the total food intake by
rainbow from Cottonwood Creek and Was'illa Lake was fish, predomin-
antly sticklebacks (Gasterosteidae). They also noted that lakefish feed more heavily on sticklebacks than do stream residentfish. Engel (1970) found that st'icklebacks comprised more than
75% of the food (by volume) of rainbow trout larger than 254 rrn in
Gruski Lake on the Kenai Pen'insula. Insects (especial ly
Trichoptera larvae) were of secondary importance in the diet of
these large fish. Trout less than 254 mm preferred insects
(especially Diptera, Trichoptera, and Co]eoptera). Engel (1970)
228
noted that the rainbow trout switched to a diet of fish after
attaining a size of 204 to 254 mn, regardless of the availability
of other food.
Rainbow trout in Lower Talarik Creek in Southwest Alaska consume
mainly eggs of sockeye salmon (0ncorhynchus nerl<a [l|lalbaum]);
aquatic Ai"pterans (mid6es ) ; and TrfEho[T[Fa-iTivae CRussel I 1977) .
Forage fiihes, especial ly pond smelt (Hypomesus ol jdus) ' were
eatei by troui ov'er 175
- mm i n I ength (T'ussejl- tTlT- tn the
Susitna-River, rainbow trout concentrate near tributary mouths and
in sloughs during the summer, presumably to feed on eggs.of pink
and chu-m salmon, which spawn in these areas (Sundet and Wenger
1e84).
Russell (1980) reported that rajnbows from the Chilikadrotna and
Mulchatna rivers 'in southwestern Alaska frequent'ly consumed small
rodents. One Chilikadrotna rainbow stomach contained a total of
five shrews.B. Types of Feeding Areas Used
In'streams, the-highest invertebrate production usual'ly occurs in
riffle areas (velocity 0.46 to 1.07 m/s) with a substrate of
coarse gravel (:.2 to 7.6 cm diameter) and rubble (7.6 to 30.4 cm
diametei) (Reiier and Bjornn L979). Everest and Chapman (1972)
observed'that steelhead juveniles rearing in Idaho streams nearly
always were found close to (but not in) areas of fast-water
inveitebrate production. Steelhead juveniles remained near the
bottom in low velocity areas, except when darting after food
i tems.
Scott and Crossman (tgZS) state that rainbow trout feed on the
bottom most often but also rise to the surface to feed on emerging
or egg-l ay'ing i nsects . The presence of l arge ,numbers of
frichditeri lirvae in ra'inbow from Grusk'i Lake (Enge1 1970) and
Talarik Creek (Russell 1977) supports that statement.
Observatjons of radio-tagged rainbow trout in the Susitna River
revealed that thejr distribution within a microhabitat may be
dependent on the food source (Suchanek et al . 1984). In areas
where rainbow trout were feeding on salmon €99S, they were closely
associated with spawning salmon and used shallow water riffles
with cobble substrate for cover (ibid.). In areas where rainbow
trout were apparently feeding on aquatic insects, they were found
in deep pools and used turbulent water and depth,.along with the
rubble/cobble substrate and debris, as cover (ibid.).
Factors Limi ti ng Avai I abi I'ity of Food
Excessive sedimentation may inhibjt production
invertebrate fauna (Hall and McKay 1983).
c.of aquatic
Small rainbow trout (1ess than 230 mm) compete with threespine
stickleback (Gasterosteus aculeatqs ILinnaeus]), for food in some
lakes (Engel -tgZO-I. UF-on-r€acTing a length of 230 mm, however,
forage fish such as sticklebacks become important in the diet. In
fact, the availabi'lity of forage fish may be necessary for
rainbows to reach maximum size (Morrow 1980).
229
V.
The magnitude of sockeye salmon runs in Southwest Alaska streams
may affect the general condition of iuvenile rainbows in that area
(Russel 1 L977). Rainbow trout have been reported to fol low
spawning sockeye salmon upstream in Idavin creek in the Naknek
drainage in southwestern Alaska (Gwartney 1983). The availability
of 'large numbers of salmon eggs in the summer m?y enhance the
rainbows' chances of overwinter survival (ibid. ). A similar
relationship between the size of sockeye salmon runs and the
growth of stee'lhead trout was also noted in Petersburg Creek in
Southeast Alaska (Jones 1978).D. Feeding Behavior
Maciolek and Needham (1952) found that rainbow trout in Convict
Creek, Ca'lifornia, fed actively all winter, even in frazil ice
conditions. The volume of food in rainbow trout stomachs from
Paul Lake, British Columbia, was on'ly slight'ly less in winter than
in surnmer (Larkin et al. 1950). Studies in Gruski Lake on the
Kenai Peninsula also indicate that rainbow trout continue to feed
in winter under the ice (Enge1 1970).
REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat
Spawning takes place in streams, usually in a riffle above a pool
(Morrow 1980). Side channe'l s, the tai I s of pool s just above
riffles, and areas along the anterior portions of islands are
frequently used (Russell 1977). More specific spawning habitat
characteristics are included in the Physical Hab'itat Requirements
portion (section III.) of this account.B. Reproducti ve Seasona'l i ty
Genera'l'ly, rai nbow trout spawn duri ng May and June (ADF&G 1978).
Russell (L977) found that rainbow trout in Lower Talarik Creek in
Southwest Alaska spawned from late April through mid June, with
the spawning peak occurring between early May and early June,
depending upon water temperature. In 19.83, Susitna River rainbow
trbut spawned in late May to early June (Sundet and Wenger 1984).
Peak steelhead spawning in the Copper River occurs from late May
through mid June (Burger et al . 1983). In a samp'le of 10
steelhead taken from the Anchor River on May 10, two of six males
had loose milt and four did not; none of the four females had
loose eggs (Wallis and Balland 1983).C. Reproductive Behavior
Brbeding behavior is typically salmonid (Morrow 1980). The female
digs a iedd by turning on her side and giving several upward flips
of her tail. Displaced sand and gravel is washed downstream,
eventua'l1y resulting'in a pit somewhat longer and deeper than the
female's body (ibid.). When the redd is finished, the female
drops into the pit and is joined by the male. Both fish gape
their mouths, guiver, and extrude eggs and milt for a few seconds.
One or more smal'1, subordinate males may dart alongside the female
and participate in the spawning act (Morrow 1980, Allin and Baxter
1957). As soon as spawning is completed, the female moves to the
230
D.
upstream edge of the redd and digs again, thus displacing. grave'l
downstream ind covering the eggs. This process is repeated e_ither
with the same or other males until the female's egg supply is
exhausted (Morrow 1980).
Age at Sexual Maturity
G6neral'ly, the age ai whjch these trout reach sexual maturity is
between three and five years, with males usually maturing a year
earl ier than females (Morrow 1980). Most rainbows in Lower
Talarik Creek in Southwest Alaska mature at ages six and Seven
(Russell 1977). In the Susitna River, rainbow trout of both sexes
spawn after age V (Sundet and Wenger 1984). Steel head i n
Southeast Alask-a spend from two to five years in the Streams
before migrating to sea and then spend at least two years. at sea
before reiurning to spawn, so they are normally five or six years
old at maturity (Jones 1978).
Wallis and Balland (1983) found that among fist-time steelhead
Spawners'in the Anchor River, the maiority of the females had
spent three years in fresh water and two in the ocean. Among the
miles, there- were about equa'l numbers of fish that had spent one
and two years in the ocean; most had spent three years in fresh
water.
Frequency of Breeding
Nany raiirbow and Ste;lhead survive to spawn more than once (Morrow
198b). Spring runs of steelhead in Southeast Alaska contain 20 to
50% repeat spawners (Jones 1978). Fall runs of steelhead in
Southeast contain 15 to 25% repeat spawners (Jones 1978). The
percent of repeat spawners among.Anchor River stee'lhead in
bifferent years'has ranged from 3.5 (Redick 1968) to 33% (Wallis
and Bal I and 1983).
Rainbow trout from Lower Talarik Creek in Southwest Alaska also
may spawn several times (Russell 1977). Generally, 1arge, older
feirales are less l'ike'ly to survive spawning than younger ones, and
males are less likely to survive than females (Morrow 1980).
Fecund'i ty
Fecundity varies with the size and condition of the femal_es (A1l in
and Baxter 1957 , Scott 1962). Fecund'i ty of steel head i n
Petersburg Creek in Southeast Alaska averaged 5'286 -eggs per
female from 1973 to 1976 (Jones 1976). Fecundity of steelhead 655
to 770 nn'in length from the Anchor River ranged from 4'0ql to
7,502 eggs in a sample of 10 females (Waltjs and Balland 1983).
Rainbow from Talarik Creek in Southwest Alaska averaged 3'431 eggs
per female (Russel L977). Rainbow from Cottonwood Creek in
Southcentral Alaska averaged 489 to 2,042 eggs. per. fema'le,
depending on size (Allin and Baxter 1957). Morrow (1980) gives a
geheral -fecundity value of 3,250 eggs for rainbow trout and
steel head.
Incubation Period
Eggs usually develop to hatching in a period of four to seven
weetcs ( i bi d: ) , a'l though the time of devel opment vari es wi th the
stream
.temperature
and may take up to four months (ADF&G 1978).
E.
F.
G.
231
Young-of-the-year rainbow trout were found on July L7 in Lower
Talaiik Creek (Southwest Alaska), 68 days after peak rainbow
spawning (Russel1 1974). Steelhead fry in Southeast Alaska emerge
f i^om thi 'gravel
i n July (Jones i978). Al I i n and Baxter ( 1957 )
found thaC approximately 1100 heat units (based on 11 A.M. daily
temperatures ( [ Fahrenhei t] ) and presumably cal.cu'lated by summi ng
the'difference of these temperatures from 32'F) were required for
eggs to develop to fry with absorbed yolk sacs.
VII. MOVEMENTS ASSOCIATED h|ITH LIFE FUNCTIONS
Rainbow trout and steelhead populations follow several different life
history patterns. Some rainbow trout remain in streams for their
entire- ljfe and do not undertake any 'long migrations. Juveniles of
other rainbow trout populations move into lakes after a year or more
(four to five years in Talarik Creek populations). Rainbows, however,
do not spawn in lakes. Most 'lake-dwelling rainbos trout return to
. streams to spawn in the spring (Morrow 1980). Russell (1977), howev_er,
found rainbow in Talarik Creek that return to the stream in the fa'll
(though they sti11 do not spawn until the following spring). Hartman
et a'l-. (tg6Z, 1963, and 1964) also noted rainbows moving from Brooks
River into Brooks Lake (both in the Naknek drainage) until late July,
fo]lowed by a smaller migration from the lake to the rjver through
September. Lake-dwelling ra'inbows usually. move back to the lake three
to six weeks after leaving it (Morrow 1980).
Steelhead juveniles remain in the stream for general'ly one to four
years (usually two) (ibid.) and then move downstream in the spring and
summer to marine waters. Steelhead are found throughout most of the
north Pacific ocean, north of 42" north latitude. Seasonal shifts in
distribution of ocean steelhead are associated wjth changes in water
temperature. Steelhead in the North Pacific 0cean generally move north
and west in late winter and early spring and shift to a southeasterly
movement jn'late summer, fall, and early winter (Sutherland 1973).
All steelhead spawn in the spring; thejr return migration to the
streams, however, ffidY take place in spring' Summer' or fall (Jones
1978). Spring-run steelhead are near'ly ripe when they enter the stream
from late February to mid June, and they. spawn that same spring'
spending about a month in fresh water (Jones 1975). Surmer-run
steelhead enter the stream in June and July and do not spawn until the
follow'ing spring (Jones 1978). Fall-run steelhead return from mid
September to November and also do not spawn until spring.
VII. FACTORS INFLUENCING POPULATIONSA. Natural
Rainbow and steelhead juveniles are subject to predation by
various species of fish, including other trout, chars, and coho
salmon smdlts (Scott and Crossman 1973). Cannibalism also occurs
(McAfee 1966).' Diving birds (e.g., mergansers and kingfishers)
and mammals also take a small number (Scott and Crossman 1973,
McAfee 1966).
232
Young rainbow trout potentia'lly compete with several other fishfor food, including other salmonids and sticklebacks (Scott and
Crossman 1973, Engel 1970). Adult rainbows compete for food with
other bottom-feeders and wjth other predaceous fish (Scott and
Crossman 1973).
High winter mortalities of rainbow trout may be caused by physical
catastrophies such as dewatering, collapsed snow banks, and anchor
ice formation (Needham and Jones 1959, Needham and Slater 1945).
The greatest natural mortaf ity of salmonids occurs during earlylife stages and is greatly influenced by environmental factors
(Straty 1981). These factors include flood'ing, sedimentation,
stream temperature, and scouring of stream beds by ice.
Wal I i s and Bal I and ( tget ) reported spawni ng morta'l 'i ti es of 80 to
85% in steelhead from the Anchor River. Rainbow trout also suffer
from high spawning mortalities (Sundet and Wenger 1984). For more
information on spawning mortality, see the Frequency of Breeding
section of this report.B. Human-relatedA summary of possi bl e impacts from human-rel ated activi ties
includes the following:o Alteration of preferred water temperatures, pH, dissolved
oxygen, and chemical compositiono Alteration of preferred water velocity and deptho Alteration of preferred stream morphologyo Increase in suspended organic or mineral materialo Increase in sedimentation and reduction in permeability of
substrateo Reduction in food supplyo Reduction in protective cover (e.9., overhanging stream
banks, vegetation, or large rocks)" Shock waves in aquatic environmento Human harvest
(See the Impacts of Land and Water Use volume of this series for
additional information regarding impacts. )
VIII. LEGAL STATUS
The Alaska Department of Fish and Game, Division of Sport F'ish, has
managerial authority over rainbow and steelhead trout.
IX. SPECIAL CONSIDERATIONS
Stocks of Salmo gairdneri from different geographic areas have evolved
over time to spefrfTcl-a5itat conditions. - Th-us, environmental require-
ments for one stock may be different from those of a stock in anotherarea. Therefore, caution must be used when app'lying information
gathered from one geographic location to a stock found in a different
area.
233
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Hartman, W.1., lll.R. Heard, and R. Dewey. 1964. Red salmon studies at
Brooks Lake Bio'logical Field Station, 1963. USDI, MS. rept. for 1963'
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Hartman, W.1., W.R. Heard, C.W. Strickland, and R. Dewey. 1963. Red salmon
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Hokanson, K.E.F., C.F. Kleiner, and T.t^l. Thorslund. 1977. Effects of
constant temperatures and diet temperature fluctuations on specific
growth and mortality rates and yield of juvenile rainbow trout (Salmo
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Horner, N., and T.C. Bjornn. 1,976. Survival, behavior, and density of
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Stn., Contract 56, Prog. rept. 1975. 38 pp. Cited in Ra'leigh and
Hickman 1982.
Jones, D.E. 1972. Life history study of sea-run cutthroat steelhead trout
in Southeast Alaska. ADF&G, Fed. Aid in Fish Rest. Ann. prog. rept.
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. 1973. Steelhead and sea-run cutthroat life history in Southeast---ATaska. ADF&G, anadromous fish studies. Ann. prog. rept. Vol . 14.
Study AFS-42-1.
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Study AFS-42-3-8. 42 PP.
. 1,976. Steelhead and sea-run cutthroat trout life history study
-Tn
Southeast Alaska. ADF&G, anadromous fish studies. Ann. performance
rept. Vol. 17. Study AFS-42-4. 55 pp.
. 1978. A study of cutthroat steel head i n Al aska . ADF&G '
anadromous fish studies. Ann. performance rept. Vol. 19. Study
AFS-42-6. 119 pp.
.Kramer, R.H., and L.L. Smith, Jr. 1965.
brown and rainbow trout eggs and
94(3):252-258.
Larkin, P.A., G.C. Anderson, W.A. Clemens, D.C.G. Mactay. 1950. The
productibn of kamloops irout (salmo_gqirdnerii kamloops, Jordan) in
ijaut Lake, British Cblumbia. iiniv. g:t--fF-p.-TTIEE- in Carlander
1969.
McAfee, W.R. 1966. Rainbow trout. Pages L92'2L6 in {. Calhoun, ed.
Inland fisheries management. Calif. Dept. of Fjsh and Game.
McCauley, R.W., and hl.L. Pond. I97I. Temperature selection of rainbow--t;;ut (iitmo gajrdneri ) _ filgerl i!9t l! vertical and horjzontal
gradientil-T. Fish-;-Tes. Bd. Can. 28: 1'801-1'804.
McCauley, R.W., J.R. Elljot' and L.A.A. Read. 1977. Influence of
aciiimation temperature on preferred temperture in rainbow trout, Salmo
gai rdneri . Trans. Am. Fi sh. Soc. 106: 362.
McCuddin, M.E. 1977. Survival of salmon and trout embryos- and ft.y in
grivef-sand mixtures. M.S. Thesis, Univ. Idaho, Moscow. 30 pp. Cited
in Reiser and Bjornn 1979.
Macjo'lek, J.A., and P.R. Nedham. L952. Eco'log'ical effect-s of winter
conditions on trout and trout foods jn Convict Creek, Cal'ifornia' 1951.
Trans. Amer. Fish. soc. 81:202-17. Cited in carlander 1969.
Effects of suspended wood fjber on
alevins. Trans. Am. Fish. Soc.
Miller, R.B. L957. Permanence and size of home
stream-dwel1ing cutthroat trout. J. Fish. Res. Bd. Can.
Cited in Raleigh and Hickman L982.
Morrow, J.E. 1980. The freshwater fishes of Alaska.
A'faska Northwest Publishing Co. 248 pp.
territory in
14(5):687-691.
Anchorage, AK:
236
Murray, C. A. , and C. D. Ziebel I . 1984. Accl imat'ion of rainbow trout to"nfgh pH to prevent stocking mortality in summer. Prog. Fjsh-Cult.
46:176-179.'
Murray, J.B. 1984. Personal communication. Area Mgt. Bjologist' ADF&G'
Div. Sport Fish, Kodiak.
Needham, P.R., and A.C. Jones. 1959. Flow, temperature, solar radiation
and ice in relation to activitjes of fishes jn Sagehen Creek'
California. Ecology 40(3);465-474. Cited in Sundet and Wenger 1984.
Needham, P.R., and D.W. Slater. 1945. Seasonal chan_ges in growth,
moitality and condition of rajnbow trout following p1a1t_tng. Trans.
Am. Fish. soc. 73:IL7-124. Cited in sundet and wenger 1984.
phillips, R.W., and H.J. Campbel1. 1962. The embryonic survival of coho
silmon and steel head trout as i nfl uenced by some envi ronmental
conditions in gravel beds. Pages 60-73 in Fourteenth annual report of
the Pacific Maiine Fjsheries Commission-for the year 1961. Portland'
0R.
Phillips, R.W., R.L. Lantz, E.W. Claire, and J.R. Mooring. 1975. Some
ettects of gravel mixtures on emergence of coho salmon and steelhead
trout fry. Trans. Am. Fish. Soc. 104:461-466.
Rale'igh, R.F., and T. Hickman. 1982. Habitat suitability index models:
iainbow trout. USFI'JS, Off. Biol. Serv., t,{estern Energy and Land Use
Team. Revjew copy. 56 PP.
Redick, R.R. 1968. Population studies of anadromous fish populgtiols :
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management on anadromous fi sh habi tat i n western North Ameri ca.
Habilat requirements of anadromous salmonids. USDA, For. Serv. Pacific
Northwest Forest and Range Experimental Station. Gen. Tech. Rept.
PNW-96. 54 pp.
Russe1l, R. 1974. Rainbow trout studies in Lower Talarik Creek-Kvichak
driinage. ADF&G, Fed. Aid in Fish Rest. Ann. prog. rept. Vol. 15.
Proj. F-9-6, Job G-II-E.
. L977. Rainbow trout studies, Lower Talarik Creek-Kvichak.
-T-DF&G,
Fed. Aid in Fish Rest. Completion rept. Vol . 18.
Proj. F-9-9, Job G-II-E.
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-'onument
area. ADF&G, Div. Sport Fish, and USDI, NPS. 197 pp.
237
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238
Wallis, J., and D.T. Balland. 1981. Anchor River steelhead study. Annual
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. 1983. Anchor River steelhead study. ADF&G, Fed. Aid in Fish
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steelhead trout (Salmo gairdneri).a.long the Pacific Coast of North
Ameri ca . J . Fi sh ,-Res . B?. can. 23 (3 ) : 365-393.
239
I.
II.
Chinooh Salmon Life History and Habitat Requirements
Soutlrrest and Southcentral Alasha
Map 1. Range of chinook salmon (ADF&G .|978, Holmes .|982)
NAME:A. Cormnon Names: Chinook salmon, king salmon, Spring salmon, tyee'
tu'le, qui nnat, bl ackmouth
B. Scientific Name: 0ncorhynchus tshawytscha
RANGEA. Worldwide
Chinook salmon are native to the Pacific coasts of Asia and North
America, and, except for areas immediately adiacent to the coast'
it is pbssiUie ttrat they do not occur on the high seas south of
about '40oN (Maior et it. 1978). In North America, spawning
popufations r'angi from the Ventura River, California, northward to
itrb Wutlf Rivei, Kotzebue Sound, Alaska. Along the. Asian coast'
they are found from the Anadyr River, Siberia, south to the Amur
24r
Rivern and they occur in the Komandorskie Islands,. USSR, and at
Hokkaido Island, Japan (Hart 1973, Major et al. 1978).
B. Statewide
Chinook salmon are found in major river dra'inages from Southeast
Alaska to the Wulik River, Kotzebue Sound, Alaska (Major et dlt
1978). During an Aleutian Is'lands salmon study, Ho'lmes ( tgAZ)
found that thlre were no systems in the Aleutian Islands (from
Unimak Pass to Attu Island) that would provide for spawning and
rearing of chinook salmon.C. Regional Djstribution Surunary
To-supplement the distribution information presented in the text,
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale,
bul some are at 1:1,000,000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition,
a set of colored 1:1,000,000-scale index maps of selected fish and
wildlife species has been prepared and may be found in the At'las
that accompanies each regional guide.
1. Southwest. In the Kodiak area, major chinook salmon spawning
anliEing drainages include the Karluk and Red river
systems (ADF&G 1977b).In the Bristol Bay area (for waters from Cape Newenham to
Cape Menshikof and north side Alaska Pen'insula streams south
to Cape Sarichef ), major ch'inook-producing dra'inages jnclude
the Tbg'iak, Wood, Nushagak, Mulchatna, Alagnak (Branch)' and
Naknek-rivers. 0ther Bristol Bay dra'inages supporting lesser
runs of chinook salmon include the Egegik, Ugashik' Meshik,
Cinder, and Sapsuk rivers (ADF&G I977a).
Streams on the Alaska Peninsula (south and west of Moffet
Bay) and the Aleutian Islands appear to be unsuitable for
su-pporting chinook salmon (ADF&G 1977a, Homes 1982). Chinook
saimon art found in one drainage on the southside of the
Alaska Peninsula: the Chignik River system (ADF&G 1977a).
(For more detailed narrative information, see volume 1 of the
Alaska Habitat Management Guide for the Southwest Region.)
2. Southcentral. In the Cook Inlet area, major chinook spawning
a@drainagesincludetheSusitna'Kenai,andKasilofriver drainages. -In the Prjnce l,Jillaims Sound area' the
Copper River drainage accounts for most of the chinook salmon
production (ADF&G I977b, ADF&G 1978).
(For more detailed narrative information, see volume 2 of the
Alaska Habitat Management Guide for the Southcentral Region.)
III. PHYSICAL HABITAT REQUIREMENTSA. Aquatic
1 . Water qual i tY:
a . Temperature. Water temperature r_equi reme-nts play an
JnrpoTtant role in the chinook sa'lmon I ife cyc'le and
encompass an extremely wide range of temperatunes, 0 to
242
?5"C. The abi'lity to survive within this temperature
ranqe and specific requirements, however, vary b.y life
stade (i.e., egg, alevin, iuvenile, and adu'lt), thq
temferature to wfricn the f ish have been acc'limated, and
adailtations that specific stocks have made over the
course of their evolutionary history. The results of
several field and laboratory studies are provided in the
fol I owi ng paragraphs.
Egg hatching and alevjn development have occurred under
a variety of temperature regimes in hatchery - anq
laborator! conditions. Combs ana Burrows (1957) found
that I00% mortal ity of eggs occurred when water
temperatures in laboratory tests remained constant'ly at
1.7bC; and they establjshed a temperature range of 5.8
to 14.2"C for normal development if the temperatures
remained constant throughout incubation' a situation not
1ike1y to occur under natural conditions. In later
experiments, Combs and Burrows (1965) found th-at chinook
salmon eggs that had developed to the 128-ce'l'l or early
blastula-itage in 5.8oC water could tolerate 1.7"C water
for the remajnder of the incubation period, with only
normal losses. The 128-cell stage was attajned after
eggs had been incubated for 144 hours in 5.8oC water.
Aiderdi ce and Vel son ( 1978) assembl ed data from the
literature and analyzed the relations between 'incubation
temperature and rate of development from fertilization
to 50% hatch of the eggs. They found that early imposi-
tion of 'low (below 6-to 7'C), constant (having a range
around a mean not greater than 2"C) temperatures appears
to slow egg development below those rates occurring at
ambient (average daily temperatures with ranges around a
mean greater than 2oC) temperatures having_the same mean
valuei. Information in these analyses included constant
temperature values ranging from 1'6 to 18.1"C and
ambient temperature values ranging from 2.3 to 16.4'C
(ibid.).
The juvenjle (jncluding fry, finger'ling' and parr stages
of development) upper lethal limit was found to be
25.1"C und.er laboratory conditions (Brett 1952). During
the same experiment, he found that young chinook salmon
were very sensitive to low temperatures. The lower
lethal t-emperature, however, could not be precisely
defined because it appears to be conditioned by the size
of the juvenile, the temperature to which the juvenile
has been acclimated, the length of t'ime it is exposed to
low temperatures, and the osmotic balance. For young
chinook salmon acc'limated to 23"C, the I ower 'lethal
temperature was 7.4"C.
Chihook salmon eggs were hatched at the ADF&G Crooked
Creek Hatchery near Soldotna, Alaska, in waters with
243
b.
c.
gradual 'ly decreasi ng, f I uctuati ng mean dai ly
temperatures ranging from 11.1 to 4.4"C (in 1981) and
1.1.7 to 6.7"C ('in 1982). Within five weeks after
hatching, the water temperature dropped to OoC. The
a'levin were successfully incubated at this temperature
and within 4.5 months had absorbed their yo'lk sacs. Thefry were then transferred to rearing ponds that
contained 0oC waters, and feeding was begun. During
both years, the pond water temperatures remained at 0"C
for at least 70 days following the introduction of thefry. During this time, the young fish fed and grew
(Och, pers. conm. ) .
Adult spawning studies in the Columbia River watershed
revealed that temperatures at redd sites ranged from 8.3
to 11.7"C , 4.4 to 16.7"C, and 5.6 to 16.1"C for the
spri ng, summer r drd fal I runs , respect'i vely ( Burner
1951). Burrows ( 1960) jndicates that Columbia River
female chinook salmon in hold'ing ponds apparently lost
al 'l i nc'l i nati on to spawn natural 1y when the water
temperature dropped abruptly below 4.4"C.
The pH factor. There js no optimum pH value for fjsh in
lEreffiIffiver, in waters where good f ish fauna occur'
itre pH usually ranges between 6.7 and 8.3 (Bell 1973).
State of Alaska water quality criteria for freshwater
growth and propagation of fish specify pH values of not
less than 6.5 or greater than 9.0, with variances of no
more than 0.5 pH unit from natural conditions (ADEC
1e7e ) .
Dissolved oxygen (D.0). Silver et al. (1963), during
ffiund that low (1.6 ppm) dissolved
oxygen concentrations caused total mortality of chinook
embryos in l1oC waters flowing at rates of 82, 570, and
1310 cmlhr. He also found that oxygen concentrations of
2.5 ppm and more (3.5, 5.6, and 8.0 ppm) resulted in low
prehatching mortalities similar to controls reared at
IL.7 ppm. Further, embryos reared to hatching at low
and intermediate (2.5 to 8.0 ppm) concentrations
produced smaller sacfry than did embryos reared at high
(11.7 ppm) concentrations.
Juvenile chinook salmon showed marked avoidance of mean
oxygen concentrations near 1.5, 3.0, and 4.5 ppm in
laboratory experiments when summer water temperatures
were high (means of 18.4 to 22.8"C) (Whitmore et al.
1960). He also noted that juvenile chinook salmon
showed 'l 'i ttl e avoi dance of concentrati ons near 4. 5 ppm
in the fall when water temperatures were low (means of
8.1 to 13.2'C) and that no avoidance of concentrations
near 6.0 ppm occurred regardless of the temperature
ran9e.
244
Adult swimming performance is adversely affected by
reduction of D.0. concentrations below air saturation
level. Bell (1973) states that it is desirable that
D.0. concentrations be at or near saturation and that it
is especially 'important in spawning areas where D.0.
levels must not be below 7 ppm at any time. State of
Alaska water quality criteria for growth and propagation
of fish state that "D.0. shall be greater than 7 ng/1 in
waters used by anadromous and resident fish. Further,
in no case shall D.0. be less than 5 mg/l to a depth of
20 cm in the interstitial waters of gravel utilized by
anadromous or resident fish for spawning. In no case
shall D.0. above 17 ng/1 be permitted. The concentra-
tion of total dissolved gas shall not exceed LIl% of
saturation at any point of sample collection."
d. Turbidity. Sedimentation causes high mortality in eggs
and-tI evl n by reduc i ng water i nterchange i n the redd .
If 15 to 20% of the intragravel spaces become filled
with sediment, salmonid eggs have suffered s'ignificant
(upwards of 85%) morta'l ity (Be] I 1973). Prolonged
exposure to turb'id water causes gi11 irritation in
juveni 1 es that can resul t i n fungal and pathogeni c
bacterial infection. Excess turbidity from organic
materials in the process of oxidation may reduce oxygen
below safe levels, and sedimentation may smother food
organisms and reduce primary productivity (Bell 1973).
tuibid water will absorb more solar radiation than clear
water and may thus indirect'ly ra'ise thermal barriers to
migration (Reiser and Bjornn 1979).2. Water quantity:
a. Instream flow. Sufficient water velocity and depth are
ne,eded-E- al I ow proper i ntragravel water movement
(apparent velocity) so that d'issolved oxygen is
transported to eggs and alevin and, in turn, metabolic
wastes are removed (Reiser and Biornn 1979). Juveniles
are c1 osely associated wi th I ow (3.0-60.0 cmlsec,
depending on fish size) velocitjes and are typically
found in pools along the margins of riffles or current
eddies (Burger et al. 1983: Kenai River). Kissner
(1976), during studies on the meandering Nahli.n Rjver(in the Taku River drainage of Southeast A'laska)' found
that the highest densities of iuvenile chinook salmon
were located on the steep sides of S-curves below
riffles. Measured depths of iuvenile rearing areas
range from 0.15 to 0.30 m in Idaho (Everest and Chapman
I972), with water velocities of less than.5 m/sec.
Burger et al. (1983) indicate that iuvenile _chinook
salmon utilize depths up to 3 m when water velocities
are not 'limiting and avoid depths less than 6.0 cm
during their free-sw'imming stage.
245
3.
Velocity is a'lso important to iuveniles because it is
the most important parameter in determining . the
distribution of aquatic invertebrates (food sources) in
streams (Reiser and Biornn 1979).
Excess i ve ve'l oci ti es and shal I ow water may impede
migrating fish. Thompson (L972) indicates that Pacific
Noithwest chinook salmon require a minimum depth of
.24 n, with velocities less than 2.44 m/sec for
migration. No measurement of Alaskan waters for adult
mi grati on cri teri a i s avai'l abl e.
Ve1ocity is also important in redd construction because
the water carries dis'lodged substrate materials from the
nesting site. Measured flow rates at 0.12 m above the
streambed jnclude 0.186 to 0.805 m/sec in 0regon and
0.305 to I.144 m/sec 'in the Co'lumbia River tributaries
(Smith 1973). Minimum water depths at the spawning
sites ranged from 0.183 to 0.305 m in 0regon and 0.381
to 1.983- m in Columbia River tributaries (ibid.).
Burger et al. (tggg), in a Kenai River tributary stream'
found redds at depths from 61.0 to 70.2 cm. His
velocity measurements at 0.6 of total depth had mean
values of 39.6 to 94.5 cm/sec pit velocity and 70.2 to
115.9 cm/sec tailspi11 velocity. Burger et al. (1983)
also suggest that mainstream spawning might occur in
depths from 1.0 to 2.8 m, with velocities near the
bottom (0.2 total depth) ranging from 0.3 to 1.4 m/sec.
Substrate. Eqq incubation and alevin development occur in
Fu5sTrates ranging w'ide1y 'in size and composition.
Successful growth and emergence has been recorded in areas
wi th the fo'l I owi ng bottom materi al s :o 1.9 to 10.2 cm diameter materials (Bell 1973)
" 5% mud/silt/sand, 80% 15.2 cm jn diameter to heavy sand,
$% larger than 75.2 cm diameter (averages of Burner
1951: Columbia River tributaries)o 11.3% less than 0.8 cm, 28.7% 0.8 to 1.6 cm, 45% 6.4 to
1..6 cm, 15% 1,2.7 to 6.4 cm (mean values of Burger et al .
1983: Kenai River tributary)o 15.5% less than 0.8 cm, L7.9% 1.6 to 0.8 cm, 46.4% 6.4
to 1.6 cm,20.2% 12.7 to 6.4 cm (mean values of Burger
et al . 1983: Kena'i River mainstream)
General ly, sediments less than ,64 cm diameter should
comprise less than 20 to 25% of the incubation substrate
(Reiser and Bjornn 1979).
Substrate composition regu'lates production of invertebrates,
which are food sources for juveniles. Highest production is
from grave'l and rubble-size materials associated with riffle
areas (ibid.). Substrate is important to iuveniles during
winter months when temperatures fa'l I and the streambed
becomes partial 1y dewatered. During thjs period,. many
juvenile chinook salmon burrow into the substrate (Biornn
246
lg7I, Edmundson et al. 1968: in Idaho) and do not begin
growing again until the following spring (Everes^t-and Chapman
lglZ) .- Sludies on the Kenai Rjver from late fal I to ear'ly
spring found juvenile chinook salmon throughout reaches with
thrge-cobble substrate and water velocities under 30 cm/sec.
tn iiver sections without large substrate materia'ls, chinook
salmon were observed to school in poo'l-riffle interfaces and
remained close to cover such as log debris .and/or surface
ice, if these were present (Burger et al. 1983).
B. Terrestrial1. Conditjons providing security - flom qredato! s _o! othe[
ation along shorelines and
unliEffiilanks serves as cover for juveniles and adults
duri ng spri ng and summer h'i gh-f'low condi ti ons . At other
times, many (+g to 52%) of the iuvenjles were found within
one swimmiirg burst of cover provided by ove.rhangi.ng banks,
tree stumpsind branches, and large boulders (ibid.)'
Z. Protectioh from natural elements. Bank irregularities
pr dies, .with little or no
velocities, for rearing juveni'les (ibid. ). K'issner (1977)
found thal juvenile chlnook salmon were close'ly associated
with log jams and cover in the main channels of the Taku
River and in places where the river brajded and the water was
shal I ow.
IV. NUTRITIONAL REQUIREMENTSA. Food Species Used
Upon h'atching, young alevjn remajn in the gravel_fo..two to three
wbeks unti I the yo] k sac has been absorbed. Fol 'l owi n_g emergence
from the redd and while still in fresh water, juveniles feed on
p'lankton, aquatic insect larvae, terrestrial insects, salmon eggs'
hnd spiders'(Scott and Crossman 1973, McLean et a'1. 1977). They
are iharacterized as opportunistic drift and benthic feeders
(Beauchamp et a'1. 1983). Upon migration to the sea' young.chinook
ialmon dat crab larvae, amphipods, copepods, euphasi ids,
cladocerans, barnacles, and a variety of small fjsh such as sand
lance, eulachon, herring, rockfish, and smooth tongue (Hart 1973).
Adults eat fish, squid, euphasiids, shrimps, and crab'larvae
(Major 1978). Fishes make up the bu'lk (97%) of the food of marine
iAuits, with herring and sand lance being lhe most frequently
eaten (Scott and Croisman 1973). Crustaceans (composed dom'inant'ly
of euphasiids but including young crabs, crab.megalops, and other
misceilaneous forms) are -ealen -in considerable numbers in the
spring months (May and June), as documented by Pr_akash (1962) in
studi6s off the cbast of British Columbia. Merkel (1957) made a
similar finding for chinook salmon in the marine waters near San
Francisco, Californja, where euphasiids dominated the diet during
April and May. Maior (tszsl suggests that the diet of adult
chinook salmon at sea is related to the types and abundance of
food items available.
247
V.
B. Types of Feeding Areas Used
Juveniles feed in low velocity areas of streams and rivers, such
as riverbank pools formed by bank irregularities (Burger et al.
1983) and in the pools below riffles where drifting invertebrate
material prov'ides a ready food supply. During the first year at
sea, the young fish stay near shore. During the second and
subsequent years , chi nook salmon are far-rangi ng, undertake
extensive migrations, and are found over a wide range of depths'
from surface waters to depths exceeding 100 m. It is not unusual
to encounter them at depths ranging from 20 to 110 m (Maior 1978).
C. Factors Limiting Availability of Food
Sedimentation is one of the major factors that affects freshwater
food avai'lability. Excessive sedimentation may inhibit production
of aquatic planls and invertebrate fauna (Hal'l and McKay 1983).
Be'll (1973) states that primary food production is lowered above'levels of 25 JTU (Jackson Turbidity Unit) and visual references
lost above levels of 30 JTU.D. Feeding Behavior
Chinook salmon are opportunistic feeders. Food consumption is
related directly to types and abundance of items available (Maior
1978), although juvenile chinook salmon in fresh water do not seem
to uti'lize tish-as food (Scott and Crossman 1973, Morrow 1980).
Upon returning to fresh water, adult salmon no longer feed but'live off the fat stored up in the ocean (Netboy 1974).
REPRODUCTIVE CHARACTERISTI CSA. Breeding Habitat
The general nature of the spawning ground, which may be located
from-just above t'idal limits to great distances upstream (over
3,200 km jn the Yukon River) varjes considerab'ly (Mayor 1978).
Main channels and tributarjes of larger rivers serve as the maior
chinook spawning areas (Scott and Crossman 1973). Norma.'|1y, the
spawning groundi are characterized by stream underflow (downwel-
I i ng cuments or i ntragravel fl ow) created by the depth and
velocity of the water rather than being associated with the
emergence of groundwater (Vronskiy I972, Burner 1951). Vronskiy
found that 95% of the redds in the Kamchatka River, USSR, were
situated precisely at the transition between a pool and a riffle.
Burger (1983) found that many chinook salmon redds were 'located
near the upstream tips of vegetated islands in the Kenai River
where I oose, clean gravel s aggraded and where predomi nant
substrates ranged from 1.6 to 6.4 cm diameter materials. Areas
just below'log jams, where flow through the gravel is increased as
a consequence of reduced surface flow, are also favorite spawning
sites (Major 1978).
Exceptions to what may be considered normal breeding habitat and
behavior have been documented. During late 0ctober and early
November .|965, approximately 50 chinook salmon from University of
Washington hatchery stocks spawned in groundwater seepage areas of
gravel and sand beaches in Lake Washington (Roberson .l967). This
248
B.
C.
behavior is believed to have resulted from crowding and high water
temperatures, both unfavorable conditions, at the hatchery hgming
pond. Although the returns were similar jn .|964, .|965' and .|966'
the biomass in .|965 was 1.81 and 1.82 times that in .|964 and 1966,
respectively. A decline in the rate of entry was noted in .|965'
when water temperatures rose to about 14.4"C during peak entry.
In .|965 and 1966, the water temperature dropped from about 14.4 to
11.l'C during the entry period. Also, during the .|965 return, the
water temperatures rema'ined .6 to 1.4"C warmer for the remainder
of the run than during the same time frames in .|964 and'1966. A
sample of several redds, approximate'ly two weeks after spawning
had occurrred, revealed thatn of al'l eggs recovered, most had been
fertilized, but all were dead (ibid.).
Breeding Seasonal ityIn Alaska, mature chinook salmon ascend the rivers from May
through Ju1y. General'ly, fish that appear at the river mouth
earl iest migrate farthest (Scott and Crossman 1973). Peak
spawning occurs from July through September (Morrow 1980).
Breeding Behavior
As with other salmon, adult chinook salmon return from the sea and
normally move into their natal freshwater streams to spawn.. The
female selects the spawning site and digs the redd (nest) by
turn'ing on her si de and thrashi ng her ta'i I up and down. The
current washes I oosened substrate material downstream, and a
depression 35 to 60 cm deep is formed jn the river bottom (Burner
1951, Morrow 1980, Maior 1978). Eggs and sperm (milt) are
released simultaneously and deposited in the redd. After egg
deposition, the female moves to the upstream margin of the redd
and repeats the digging process. Dis'lodged substrate is washed
over the eggs. In this manner, the eggs are covered and prevented
from washing away. The process is repeated many times, and the
redd appears to move upstream (Burner 1951). As a result of the
continued digging, the redd may grow to become 1.3 to 5.6 m in
length and 1-5 to 3.3 m wjde (Morrow 1980, Burger et al. 1983). A
female may dig several redds and spawn with more than one male
(McPhail and Lindsey 1970). Males may also spawn with several
females (ADF&G 1977, Morrow 1980).
Age at Sexual Maturity
The age at which chinook salmon reach sexual maturity ranges from
two to eight years (generally zero to two years in fresh water and
one to seven years at sea), although the vast maiority of the fish
mature in their third to sixth year. Age at maturity, like
freshwater age and ocean d9€, tends to be greater in the north
than in the south because more northern populations spend a longer
time at sea (Major 1978, Scott and Crossman 1973). From
California northward to Cook Inlet, Alaska, for example, three,four, and five-year-o1d fish prevail (there are significant
numbers of six-year-o1ds in some areas, but few if any seven or
eight-year-olds). Five-and-six year olds dominate runs from
D.
249
Bristol Bay northward, but seven and eight-year-olds are not
uncomrrcn (Maior 1978).E. Fecundity
Chinook fecundity varjes by stock and the size of the female;
however, northern stocks generally produce more eggs. In Alaska,
the number of eggs ranges from 4 ,ZqZ to L7 ,255 per femal e (Morrow
1980, Burger et al . 1983).F. Frequency of Breeding
Rs with;ll Pacific salmon, the spawning cycle is terminal. Both
male and female die after spawning.
G. Incubation Period/Emergence
The amount of time required for eggs to hatch is dependent upon
many interrelated factors, includin-g- 1) dissolved oxygen, ?) water
temperature, 3) apparent vel.ocity in grave'l ' 4) biolo-gical oxygen
demind, 5) substrate size ('limited by percentage of small fine
material,' 6) channel gradient and 7) configunation, 8) water
depth, g) suitace water-disch.arge and ve'loci!V, lr0_) permeabil !t.)r,ii) p6roilty, and 12) light (Re-iser and Bjorhn !979, Hart 1973).
Genei^ally ipeaking, factbrs 4 through 12 influence/regulate the
key factors 1, 2' and 3.
Eg-gs requ'ire iUout 900 temperature units (TU) to hatch and become
aTivins and an additional 200 to 800 TUs to absorb their yo'lk sac
(Burger et al. 1983). The TUs for one,-day = m99I 24-hour water
iemperature jn degrees Farenheit - 32"F + 1oF if the mean
temilerature is 32"F-. Incubation of the eggs takes place with both
ascbnding and descending water temperatures (Scott and Crossman
1973). Depending on the time of spawning and the- water tempera-
ture, the iggs uiually hatch in late winter or ear'ly spring (Gusey
tglgi. The--new'ly haiched f i sh, or al evi ns , remai n i n _t_he gravel
untii the attached yolk sac has been absorbed, normally two to
three weeks after hatching. The juveniles then work thejr.way up
through the gravel to belome free-swimm'ing, feeding fry (Morrow
1e8o).
VI. MOVEMENTS ASSOCIATED h,ITH LIFE FUNCTIONS
A. Size of Use Areas
From studies of Columbia River tributaries, Burner (1951) suggests
that a conservative figure for the number of pa'irs of salmon that
can satisfactorily utilize a g'iven area of spawning grave'l may be_
obtained by divici'ing the area by four times the average. size of
the redds. The redd area can be computed by measuring the tolgl
length of the redd (upper edge of pit to lower 9_dge of tailspill)
and-the average of siveral equidistant widths (Reiser and Bjornn
1979). Burgei et al. (1983) ljst mean measurements for a Kenai
River tribulary stream indicat'ing that chinook salmon redds are
about 4.37 m2-in size. Mean values for mainstream Kenai River
chinook salmon redds, however, are 6.38 m2.
B. Timing of Movements and Use of Areas
Young- of the year juveni'les move downstream in the fall to
overiinter in aieas oi the stream with larger substrate (possibly
250
c.
because it prov'ides better cover) (Biornn I97I, Burger et al.
1983). 0utmigrating smolt bound for the sea depart fresh water in
the springtime. Maior and Mighell (1969), during studies on the
Yakjma River, Washington, noted that smolt outmigrations tended to
be nocturnal.
Adults return to fresh water during the period of May through
July. Studies on the Kenai River (Burger et al. 1983) indicate
that of all radio-tagged adults return'ing to the spawning grounds'
most moved between -t+OO and 2200 hours. Neave (tS+S1, during
studies of the Cowichan River, Vancouver Island, Britjsh Columbia,
found that adult chinook salmon moved upstream main'ly in the
daytime.
Migration Routes
Large rivers Serve as corridors for smolt outmigration. Barriers
to adult upstream movement include excess turbidity' high
temperatures (20.0"C or more), sustained h'igh-water velocities,
and'blockage of streams (log iams, waterfalls) (Reiser and Bjornn
1979). tlJhile in the marine environment, first-year ocean fish are
confined primarily to coastal areas and are much less abundant in
the open ocean (Maior 1978). During the second and subsequent
year of ocean 1ife, they are found widely djstributed in the North
Pacific Qcean and Bering Sea. Morrow (1980) states that chinook
salmon from Alaskan streams enter the Gulf of Alaska gyre and move
extensively across the North Pacific. In the spring, they seem to
be scattered across the northern Pacific and in the Bering Sea,
and during the summer their numbers increase in the area of the
Aleutian Islands and in the western Gulf of Alaska. Many of the
inshore fish of Southeast Alaska, however, appear to be of local
origin (Morrow 1980).
Major (tgZg) suggests that except for areas irnmediately adjacent
to the coast it is possible that chjnook salmon do not occur in
the high seas south of 40"N. The central Bering Sea is a feed'ing
ground and migration path for immature chinook salmon in Western
Alaska (defined as the area from and including Bristol Bay north-
ward to Point Hope). Tag recoveries are known to occur in the
Bering Sea as far west as 172"12'E (at 59'03'N), whereas scale-
pattern and maturity studies, combined with seasonal distribution
and Japanese mothership and research vessels information, push the
range further west, to probab'ly at least 160o to 165"E (Major
1978). These same stocks have been found as matures in the North
Pacific 0cean just south of Adak at 176"18'l.| (at 51'36'N).
Scale-pattern analysis shows tentatively that they may extend from
160o-170" E to at least 175o W; but their distribution to the
south over this range, dt least beyond 50" N, is even more
uncertain ( ibid. ).0ther North American chinook salmon (including stocks from central
Alaska [Yakutat] southward) are known to occur as 'immatures in the
North Pacific 0cean as far west as 1.76"34'W (at 59'29'l^l), but no
fish from these stocks have yet been found in the Bering Sea. For
these stocks, it is known only that chinook salmon are widely
ZJI
scattered in the Gulf of Alaska and farther south but that their
princi pa1 occurrence i s i n rel at'ive'ly I arge concentrations close
to shore ( ibid. ).
VII. FACTORS INFLUENCING POPULATIONS
A.Natura'l
Juvenile chinook salmon are preyed on by other fish (e.9. 'rainbow, cutthroat, Dolly Varden, coho salmon smolts, squawfish'
and sculpins) and birds (e.g., mergansers, king fishers, terns,
osprey, other di vi ng bi rds ) . Estuari ne and mari ne_ predators
inbtuie fish-eating birds, pelagic fishes, killer whales, seals,
sea I ions, humans, and poss'ibly the Pac'ific lamprey (Scott and
Crossman !973, Beuchamp et al. 1983).
The greatest natural mortality occurs in fresh water during the
early life stages and is greatly influenced by the environment
( Straty 1981 ) ; therefore , de1 eteri ous changes i n freshwater
qua'l'ity, quantity, or substrate are most detrimental .
Flooding ian either wash away or bury eggs. Natural sedimentation
can smother eggs.
Human-rel atedA summary of possi bl e impacts from human-re1 ated activi ties
i nc'l udes the fol l owi ng :o A]terat'ion of preferred water temperatures, pH, dissolved
oxygLln, and chemical compositiono Altiration of preferred water velocity and deptho Alteration of preferred stream morphologyo Increase in suspended organic or mineral material
" I ncrease 'i n sedi mentati on and reducti on i n permeabi 'l i ty of
substrateo Reduction in food suPPlYo Reduction in protective cover (e.9., overhanging stream
banks, vegetation, or large rocks)o Obstruction of migration routeso Shock waves in aquatic environmento Human harvest
(See the Impacts of Land and Water Use volume of this series for
additional information regarding impacts.)
B.
VIII. LEGAL STATUSA. Managerial AuthoritY
fne Alaska Department of Fish and Game manages the fresh waters of
the state and the marine waters to the 3 mi limit.
The North Pacific Fishery Management Council is composed of 15
members, 11. voting and 4 nonvoting members. The 11 are divided as
follows:5 from Alaska,3 from t.lashington,3 from state fishery
agencies (Alaska, Washington, 0regon). The four nonvoting members
iic'lude the director of-the Pacific Marine Fisheries Conrnission;
the djrector of the U.S. Fish and t,lildlife Service; the commander,
17th Coast Guard District; and a representative from the U.S.
Department of State.
252
The counci 1 prepares fi shery management p1 ans, whi ch become
federal law and apply to marine areas between the 3-m'i limit and
the 200-mi limit. l,lith regard to salmon, the only plan prepared
to date is the Salmon Power Troll F'ishery Management Plan.
The International North Pacific Fisheries Commission (INPFC), a
convention comprised of Canada, Japan, and the United States' has
been establ ished to provide for scientific stud'ies and for
coordinating the collection, exchanges, and analysis of scientific
data regarding anadromous species.y1ith regard to salmon, the INPFC has also prepared conservatjon
measures that limit the location, time, and number of fishing days
that designated high seas (beyond the 200-mi'limit) areas may be
fished by Japanese natjonals and fishing vessels.
IX. SPECIAL CONSIDERATIONS
Caution must be used when extending information from one stock of
chinook salmon to another stock. Environmental conditions for one area
must not be treated aS absolute; the stocks (races) have
acclimated/evolved over time and space to habitat conditions that can
vary greatly.
X. LIMITATIONS OF INFORMATION
Very little life h'istory and habitat information concerning Alaskan
chiirook salmon has been- collected/published. Most of the available
information has been documented from Pac'ific Northwest and Canadian
field and laboratory studies.
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at 'di fferent water ve'loci tJes . Trans. Am. Fi sh. Soc. 92(4) 2327'343.
Smith, A.K. L973. Development and app'lication of spawning velocity_and
depth criteria for 0regon salmonids. Trans. Am. Fish. Soc.
102(2): 312-316.
Straty, R.R. 1981. Trans-shelf movements of Pacific salmon. Pag_es 575-595
in D.t.l. Hood and J.A. Calder, eds. The eastern Bering Sea shelf:
6Eeanography and resources, Vol. I. USDC: NOAA, 0MPA.
Thompson, K. 1972. Determining stream f'lows for fish 'life. Pages-.31-f0 j-[' Proceed'ings, instream flow requirement workshop, Pacific Northwest
River Basin Comm. Vancouver, WA.
Vronskiy, B.B. 1972.Reproductive bio'logy of the Kamchatka River chinook
salmon (0ncorhynchus tschawytsha [l.lal baum] ) .J. of lcth.
I2(2):25e-273.
Whitmore, C.M., C.E. l'larren, and P. Doudoroff. 1960. Avoidance reactions
of the salmonid and centrarchid fishes to low oxygen concentrations.
Trans . Am. Fi sh. Soc. 89( I) zl7 -26.
256
Coho Salmon Life History and Habitat Requirements
Southwest and Southcentral Alasha
Map 1. Range of coho salmon (ADF&G 1978, Morrow .|980)
I. NAMEA. Cormon Names: Coho salmon, coho, s'ilver sa'lmon, sea troutB. Scientific Name: 0rlgllynchus- kisutch
I I. RANGEA. Worldwide
The coho salmon occurs natura'l1y in the Pac'if ic 0cean and its
tributary drainage. In North America, it is found from Monterey
Bay, California, north to Point Hope, Alaska. In Asia, it occurs
from the Anadyr River in northeastern Siberia south to Hokkaido,
Japan (Scott and Crossman 1973).B. StatewideIn Alaska, coho salmon are abundant from the Dixon Entrance
(Southeast Alaska) north to the Yukon River. Evidence suggests
ililtil
257
c.
that coho are rare north of Norton Sound (ADF&G 1977).
Regional Distribution Summary
To supplement the distribution information presented in the text,
a series of b'luelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 _scale,bui some are at 1:1,000,000 sca1e. These maps are availab'le for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition,
a set of colored 1:1,000,000-sca'le index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.
1. Southwest. In the Kodiak area, many streams have runs of
ffilion; however, the runs are 'late in the season, and
escapement f i gures are i ncomp'l ete ( i bi d. ) .
In the Bristol Bay area (for waters from Cape Newenham to
Cape Menshikof and northside A'laska Peninsula streams south
to Cape Sarichef), maior coho sa'lmon-producing drainages
include the Togiak and Nushagak systems, with smaller runs
found in the Kulukak, Naknek, Kvichak, Egegik, and Ugashik
systems ( Mi ddl eton 1983 ) . Further south on the Al as ka
Peninsula, important northside coho salmon-producing systems
are found at Nelson Lagoon, Port Heiden, and Cinder River.
Smaller fisheries also exist at Swanson Lagoon and Ilnik
(Shau1, pers. conn. ).For south-side Alaska Peninsula streams and the Aleutian
Islands, data are scarce concerning coho salmon production.
The best-known runs on the South Peninsula occur in Russel
Creek, Mortensen Lagoon, and Thin Point Cove at Cold Bay
(ADF&G I977a). A few streams on Unalaska Island and several
small drainages in the Aleutian Islands contain coho salmon,
but the size-of the run is unknown (Ho'lmes, pers. comm.). It
is known that the Ch'ignik River system produces most of the
coho sa'lmon utilized by the commercial fishery in the Chignik
area. Other streams in the Chignik area also contain coho
sa'lmon, although the size of the runs is not known (ADF&G
L977a). (For more detailed narrative information, see volume
1 of the Alaska Habjtat Management Guide for the Southwest
Regi on. )2. Southcentral . In the Upper Cook Inlet area, major coho
Falnron-+ivrn"ing and rearing drainages include the Susitna,
Kenai, and Kasilot river systems (Mclean et al . 1977a). In
the Lower Cook Inlet area' coho salmon are found in the
English Bay lakes system, Clearwater Slough, and the Douglas'
Big Kamishak, Little Kamishak, and McNeil river systems
(ADF&G .|983b). In the Prince blilliam Sound area, coho salmon
are the dominant species in the Bering River (ADF&G .|978).
They are also found in numbers in the Copper and Katalla
river drainages (ADF&G .|978, l9B3c).
(For more detailed narrative information, see volume 2 of the
Alaska Habitat Management Guide for the Southcentral Region.)
258
III. PHYSICAL HABITAT REQUIREMENTSA. Aquat'i c
1 . Water qual i ty:a. Temperature. Egg incubation and alevin development have
occuFreAlVer a wide range of temperatures. Reiser and
Bjornn (1979) list recommended incubation temperatures
for coho salmon as 4.4 to 13.3"C.
Under laboratory conditions, Brett (1952) found the
upper lethal temperature limit of_juven'i1e coho salmon
to be 25.0"C. Reiser and Biornn (1979) list preferred
temperatures for rearing iuveniles as 11.8 to 14.6"C.
Bustard and Narver (1975), during winter studies on a
small stream in Vancouver, British Columbia, found that
at 7"C or less the young coho were associated with water
velocjties of less than 15 cm/sec. They also noted that
as water temperature decreased from 9 to 2"C the coho
salmon moved closer to cover (e.9., 1ogs, uprooted tree
roots , debrj s accumul ati ons , overhangi ng banks , and
overhanging brush).
While feeding in the ocean, maturing coho salmon have
been found in areas where surface temperatures have
ranged from 4.0 to 15.2'C, with most being found in the
8 to I?"C range. Various evidence, however, indjcates
that coho may occur in even colder waters (Godfrey
1965).
Adult entry into fresh water may be triggered in part by
a rise in water temperature (Morrow 1980). Spawning
occurs over a wide range of water temperatures. Godfrey
(1965) cites Gribanov, who reported water temperatures
during spawning in Kamchatka, USSR, r'ivers as low as
0.8'C- and as fi-igh as 7.7"C. Reiser and Biornn (1979)
suggest that 4.4 to 9.4"C is a more preferred temper-
ature range for spawning.
The pH factor. There is no optimum pH v_q1ue-for fish in
general; however, jn waters where good fish fauna occur'
ttre pH usually ranges between 6.7 and 8.3 (Bell 1973).
State of Alaska water quality criteria for freshwater
growth and propagation of fish specify pH values of not
less than 6.5 or greater than 9.0, with variances of no
more than 0.5 pl-L unit from natural conditions (ADEC
1e7e ) .
Dissolved oxygen (D.0. ). The groundwater that is
awning beds is usuallY high'lY
oxygenated (Godfrey 1965).
Davis et al. (1963), during laboratory tests of
sustained swimming speeds of juvenile coho salmon, found
that the reduction of oxygen concentration from air
saturati on I evel s to 7 , 6, 5, 4, and 3 mg/l usua'l ly
resulted in reduction of the maximum sustained swimming
speed by about 5, B, 13, 20, and 30%, respectively.
b.
c.
259
2.
Adult swimming performance is also adversely affected by
reduction of D.0 concentrations below air saturationlevel. Be]l (1973) states that it is desirable that
D.0. concentrations be at or near saturation and that itis especial'ly important in spawning areas, where D.0.
levels must not be below 7 ppm at any time. State of
Alaska water quality criteria for growth and propagation
of fish state that "D.0. shall be greater than 7 ng/l in
waters used by anadromous and resident fish. Further'
in no case shall D.0. be less than 5 mg/l to a depth of
20 cm in the interstitial waters of gravel utiljzed by
anadromous or resident fish for spawning. In no
case sha'll D.0. above 17 mg/l be permitted. The
concentration of tota'l dissolved gas shall not exceed
110 percent of saturation at any point of sample
col I ecti on . "d. Turbidity. Sedimentatjon causes high mortality to eggs
and-a'IEVTn by reducing water interchange in the redd.
If 15 to 20% of the intragrave'l spaces become filled
with sedjment, sa'lmonid eggs have suffered significant
(upwards of 85%) mortality (Bell 1973). Prolonged
exposure to turbid water causes gill irritation in
juveniles, which can result in fungal and pathogenic
bacterial infection. Excess turbidity from organic
materials in the process of oxidation may reduce oxygen
below safe levels, and sedimentation may smother food
organ'isms and reduce primary productivity (ibid.). From
investigation of the Susitna River in Southcentra'l
Alaska during L982, turbid water was found to be a
strong factor that influenced iuvenile fish distribu-
t'ions. This study'indicates that rearing coho salmon
apparently avoid turbid water (ADF&G 1983a). Turbid
water will absorb more solar radiation than clear water
and may thus indirectly raise thermal barriers to adult
upstream spawning migration (Reiser and Bjornn 1979).
Water quanitity:a. Instream flow. Sufficient water velocity and depth are
neeGI--To a1 I ow proper i ntragravel water movement
(apparent velocity) so that djssolved oxygen - is
transported to eggs and alevins and in turn metabolic
wastes are removed (ibid.).
Juveniles after emerging from the grave'l stay almost
entirely in poo'ls, avoiding riffle areas (Morrow 1980).
Burger et al. (1983), during studies on the Kenai River,
Alaska, and its tributaries, found that recent'ly emerged
juven'i1es (less than 50 mm long) in the main stem of the
river were close to banks and often in reaches where the
river had flooded terrestrial areas. Most of these
juveni'les were found in zones of zero water velocity'
and almost 80% were captured in areas of less than 6.1
260
cm/sec mean water-column velocity. Larger iuvenile coho
salmon (51 to 7t mm) were typically captured in creek
mouth basins, backwater poo1s, and man-made canals.
Ninety percent of these fish were in habitat hav'ing no
measurabl e water ve1 oci ty. In contrast to these
findings, the iuveniles in Kenai River tributary streams
were found in pool-riffle habitat. Burger et al. (1983)
suggest that sooner-emerging chinook salmon iuveniles
may be displacing main stem spawned coho salmon into
tributaries, canals, and basins. He also suggests that
since the main stem age 0 coho salmon do not appear to
be attaining the same growth as similar age fish in the
Deshka or Susitna rivers, the areas to which they have
been forced 'is probab'ly not their preferred habitat and
may not supp'ly the dri f t food 'items that are a major
contributor to salmonid diets. Competition with
stickleback may also play a role in the lower coho
salmon growth rates.
Bovee (1978) suggests that an optimum water velocity for
coho salmon fry is from 15.2 to 18.3 cm/sec.
Stream water velocity is important to iuveniles because
it is the most 'important parameter in determining the
distribution of aquatic invertebrates (food sources) in
streams (Reiser and Biornn 1979).
Excess velocities and shallow water may 'impede migratingfish. Thompson (tglZ) indicates that Pacific Northwest
coho salmon require a minimum depth of 0.18 m, with
velocities less than 2.44 m/sec. for migration. No
measurements of Alaska waters for adult m'igration
criteria are available.
Ve'locity is also important in redd construction because
the water carries dislodged substrate materials from the
nesting site. Measured flow rates at 0.12 m above the
streambed include 19.2 to 69.2 cm/sec in 0regon and 7.6to 61.0 cm/sec in the Columbia River and tributaries
(Smith 1973). M'inimum water depths at these spawning
sites ranged from 0.122 to 0.153 m in Oregon and from
0.305 to 0.458 m in the Columbia River and tributaries.
Smith (1973) recommended the following spawning velocity
(as measured 0.12 m above streambed) and minimum depth
criteria for Oregon coho salmon as 21.0 to 70.0 cm/sec
and 0.15 m, respective]y. Burger et al . (19S3) 'lists
measured vel ocities for the Kenai Ri ver and one
tributary stream as 21.4 to 30.5 cm/sec pit velocity and
51.8 to 82.8 cm/sec tai'lspi'l'l velocity (measurement
taken at 0.6 total depth). The pit depths at these
redds were 54.5 to 76.3 cil, and the tai l spi 1'l depths
were 25.0 to 45.0 cm.Substrate. Egg incubation and alevin development occur in
aubsEFeiles ranging wide'ly in s'ize and composition. The ADF&G
3.
261
(tgll) states that optimum substrate composition is small-to-
rnedium grave'l . Generally, sediments less than .64 cm
diameter shou'ld comprise less than 20 to 25% of the jncuba-
tion substrate (Re'iser and Biornn 1979).
Substrate composition regulates production of invertebrates,
which are food sources for juveniles. Highest production is
from grave'l and riffle-size materials associated with riffle
areas ( ibid. ).B. Terrestrial1. Conditions providing security flof predqtols or oth9r€strial vegetation was the
Aomineffi cover type used by juvenile coho in their backwater
pool-rearing areas 'in the main stem Kenai River (Burger et
a'l . 1983).
Undercut banks and deep water poo'ls provide protection for
adul ts.2. Conditjons provjd'ln from naturql elements.
Columbia, noted that the juvenjle coho salmon were associated
with water velocities of less than 15 cm/sec when the water
temperature was 7"C or less. They also noted that as the
temperature dropped from 9 to 2"C young coho- salmon moved
clober to cover provided by such things as 'logs, uprooted
trees , debri s accumul at'i ons , overhangi ng banks , and
overhanging brush.
IV. NUTRITIONAL REQUIREMENTSA. Food Spec'ies Used
Upon hatching, young alevin remain in the gravel_for two or three
weeks until the yo'lk sack has been absorbed. Fol'low'ing emergence
from the gravel, the iuveniles begin feeding at or near the
surface (Morrow 1980). Maior food items at this time are
terrestrial insects, especially species of flies (Diptera) and
wasps and bees (Hymenoptera) a.nd perhaps also aphids and thripp(ibid.). Burger' et al'. (1983) found that midges (chironomids)
were dominant-in stomach samples of juvenile coho salmon in the
Kenai River, Alaska. The diet can also include mites, beetles,
springtails (Collembola), spiders, and small zoop'lankton. As the
young fish grow they consume larger food items and often consume
young sockeye salmon. In Chignik Lake, Alaska, young coho salmon
have been found to eat seven times as many sockeye salmon as do
Do11y Varden, and in other localities coho salmon may be equal'ly
serious predators (Morrow 1980). Scott and Crossman (1973) state
that'large numbers of chum and pink salmon are also taken by coho
;;lftentering the sea, young coho salmon - feed. on various
pianktonic crustaceans, p'ink aryd chum salmon fry, herring, sand
iance, other fishes, and squid (ibid.).
The food of marine adults is more pelagic and more varied than
that of many Pac'ific salmon. Fishes make up 70 to B0% of the coho
262
V.
salmon's food, invertebrates 20 to 30%, and include the following:
pi'lchard, herring, anchovy, coho salmon, capelin, Ianternfish,
Pacific saury, hake, whiting, rockfishes, black cod, sculpins,
sand lance, squid, barnacles, isopods, amphipods, euphasiids, crab
larvae, and jelly fish (Morrow 1980, Scott and Crossman 1973).
Herring and sand lance make up 75% of the volume (Pritchard and
Tester 1944). Some populations, however, remain on the crustacean
diet, such coho generally not growing as big as those that eat
fish (Prakash and Milne 1958).B. Types of Feeding Areas Used
Young juveniles feed in low velocity areas a'long streambanks and
in backwater pools and current eddies. Feeding is genera'l1y near
the surface, with drifting invertebrates the prey; young coho
sal mon feed i nfrequent'ly on bottom-dwe'l 1 i ng organi sms (Morrow
1980). As they grow in size, the iuvenjles may become serious
predators of other small fish, including other salmon species.
When the young coho salmon migrate to the sea, they tend to stay
fairly close to shore at first. The oceanic movements of coho in
the southern part of the range (i.e., Washington, Oregon, British
Columbia) seem to be chiefly along the coast, with some fish
apparently never venturing far from the coast. By contrast,
northern fish, particu'lar'ly those from Alaskan streams, spread out
all across the North Pacific and into the Bering Sea (ibid.).
Available evidence from commercial fisheries and research vessels
indicates that while at sea coho salmon occur most frequent'ly near
the surface. Individuals have been taken at greater depths, but
most coho salmon have been caught in the upper 10 m (Godfrey
1e65).C. Factors Limi ti ng Avai I abi 1 i ty of Food
Sedimentation is one of the major factors affecting freshwater
food availability. Excessive sedimentation may inhibit production
of aquatic plants and invertebrate fauna (Hatt and McKay 1983).
Bell (1973) states that primary food production is lowered above
levels of 25 JTU (Jackson Turbidity Unjt) and visual references
lost above levels of 30 JTU.D. Feeding Behavior
Food viries from place to place and with time (Scott and Crossman
1973). l^lhile on the high seas, schools may become involved in a
feeding frenzy and have been found to be eating blue lanternfish
and sauries (Hart 1973). Upon entering fresh water, adult salmon
no 'longer feed but I i ve off the fat they stored up whi'l e i n the
ocean (Netboy 1974).
REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat
Short coastal streams are usually preferred, but coho salmon are
known to spawn in spring-fed tributaries of the Yukon R'iver system
from the Bonasila River at least as far upstream as the Tanana
(Morrow 1980). Although spawning may occur in main channels of
263
B.
c.
D.
E.
1 arge ri vers , I ocati ons at the head of ri ffl es i n shal I sw
triSutaries or narrow side channels are preferred (ADF&G 1977).
Reproductive Seasonal itY
In'Alaska, coho salmon enter freshwater streams from mid July
through November (Russel I , pers.. conrm. ). .Actu-al spawning _oc.curs
betwe6n September and January (ADF&G L977). As a ru'le, fish in
the northei^n part of the range enter fresh water earlier jn the
season, with runs occurring progressive'ly later to the south
(Momow 1980).
Reproductive Behavior
As'with other salmon, adult coho salmon return from the sea and
move i nto thei r nata'l f reshwater streams to spawn. The fema'le
selects the spawning site and digs the redd (nest) by turning. on
her side and'thrashing her tail up and down. The current washes
loosened substrate material downstream, and a depress'ion 8 to 51
cm (average about 20 to 25 cm) deep is formed.in the rjver bottom
(Burner 1bSt, Morrow 1980). Eggs and sperm (milt) arF re'leased
iimultaneously and deposited in the redd. After egg deposition'
the female moves to the upstream margin of the redd and repeats
the digg'ing process. Dislodged substrate is washed over the
eggs. -in ttris manner, the eggs are covered and prevented from
wiining away. The process is repeated many times, and the redd
appearl to move upstream (Burner 1951). As a result of the
cbhtinued digging, the redd may grow to become -L.2 n2 to 6.6 m2,
with a general average of about 2.8 n2 for Columbia River basin
redds (ibid.). A female may dig several redds and spawn with more
than one male (McPhail and Lindsey 1970).
Age at Sexual MaturitY
The age at which coho salmon reach sexua'l maturity ranges from two
to sii years, although most usual'ly return from marine waters to
spawn ai age three oi four. The number of four-and five-year-o1d
fish usually increases northward (Scott and Crossman 1973).
Fecundi ty
The numbLr of eggs varies with the size of the fish' the stgck'
and sometimes the year. Numbers have been reported from 1 '440 to
i,llO; the average- probably lies between 2,500 and 3,000 (Morrow
fgeO). Godfrey '(1965) cites stud'ies of Kamchatkan (Russ'ian)
sa'lmon, where the average number of eggs was 4'883.
Frequency of Breed'ing
Rs with;ll Pacific salmon, the spawning cycle is terminal. Both
male and female die after spawn'ing.
Incubati on Peri odlEmergence
The amount of time required for eggs to hatch is dependent upon
many interrelated factors, including 1) dissolved. oxygen,
2) i'rater temperature, 3) apparent vel oci.ty i n gravel ' 4) bi ol ogi -
cit oxygen demand, 5),substrate size (limited by p.ercentage of
small fi-ne materlai ), '6) channe'l gradient and 7) c6nf iguratioh, 8)
water depth, 9) surface water distharge and vel ocity, 10) pgryga-
bility, '11) porosity, and 12) light-(Reiser 1979, Hart 1973).
F.
G.
264
Generally speaking, factors 4 through 12 influence/regulate the
key factors l, ?, and 3.
In Alaska, hatching usually takes place from mid winter to early
spring, the amount of time varying with the water temperature.
Scott and Crossman (1973) indicate that hatching times have ranged
from 38 days at 10.7"C to 48 days at 8.9" in California, and they
postulate that it might take 42 to 56 days farther north. Morrow
(1980) states that incubation takes six to nine weeks and may
require as long as five months. After hatching, the alevin remain
in the gravel for 2 to 3 weeks (some may take up to 10 weeks) and
emerge from the gravel sometime from April to June (ADF&G 1978
Morrow 1980, Godfrey 1965).
VI. MOVEMENTS ASSOCIATED t^lITH LIFE FUNCTIONSA. Size of Use Areas
Juvenile coho salmon after emerging from the gravel take up
residence not far from redds, especial'ly near the banks, where
they tend to congregate in schools. As they grow they disperse
and become aggressive and territorial. Laboratory experiments by
Chapman (1962) show that juveniles are aggressive and territorialor hierarchical in behavior. Hierarchies and territories were
organized on the basis of fish size, and smaller fish tended to
move downstream because of the continuous harassment by the 'larger
fish.
From studies of Columbia River tributaries, Burner (1951) suggests
that a conservative figure for the number of pairs of salmon that
can satisfactorily ut'ilize a given area of spawning gravel may be
obtained by dividing the area by four times the average size of
the redds. Redd area can be computed by measuring the total
length of the redd (upper edge of pit to lower edge of tailspill)
and the average of several equidistant widths (Reiser and Bjornn
1979). Burner (tgSt) states that Columbia River basin coho salmon
redds averaged 2.8 n2. Burger et al. (1983) measured three redds
(two in the Kenai River main stem, one in a trjbutary stream) and
listed their sizes. Main stem redds were 1.5 and 0.9 m long x 1.2
and 0.6 m wide, respectively. The tributary redd was 1.8 m long x
1.0 m wide.B. Timing of Movements and Use of Areas
The young coho salmon normally spend a year in fresh water before
going to sea, although some may go to sea at the end of theirfirst summer. Others, as in the Karluk River on Kodiak Island,
Alaska, ffidy stay two, three, or even four years in fresh water
(Morrow 1980). Middleton ( 1983) states that in Bristol Bay
streams coho juveniles stay in fresh water mainly two or more
years. The same is said for the Ch'ignik and Nelson Lagoon systems
by Shaul (pers. comm.), who postulates that most coho salmon on
the Alaska Peninsula probably spend two winters in fresh water.In the Taku River of Southeast Alaska, downstream movement of
juveniles bound for the sea is usually at n'ight (Meehan and Siniff
L962), and the trip is completed during the period mid April
265
through mid June. Studies of smolt outmigration_in the Bear Lake
system, near Seward, 'indicate that very. few smolts migrate pljgr
to stream temperatures attaining 3.9"C (Logan .|967), and for this
system the seaward movement of natural stocks commences during mid
Miy and continues through late September, with.50% of_the m]g1q-
tion passing the samp'ling weir by mid June (Logan_ .1967 , .|968'
.1969). Aurgir et al. (1983) suggest that the Kenai River seaward
migration occurs probab'ly from July to November.
Haiing spent two or three years in the ocean, mature coho salmon
first arrive in appreciable numbers in coastal waters of central
and southeastern Alaska early in Ju1y, and the runs extend jnto
August or September. A'laska Peninsula coho salmon sp_end only one
yeir in salt water (Shau1, pers. corm.). _ Few de-tails are known-r.egarding the times of arrival of coho salmon off western Alaska
streams, except that aga'in they are late in the season and fo1low
the runs of 'the sockeye and pink salmon (Morrow 1980, Godfrey
1e6s).
The beginning of intensive adult upstream migration -is associated
with tfie beginning of a rising tide and schoo]ing off the mouth of
a river, in bracliish waters, and occurs during the period of the
fa'l'ling tide (Gribanov 1948). When in the rjver' they move
upstreim mainly during dayfight hours (Neave 1943).
C. Migration Routes
Rivers and streams serve as corridors for smolt outmigration.
Barriers to adult upstream movement include excess turbidity, high
temperatures (20.0"C or more), sustained high-water velocitjes
(grbater than 2.44 m/sec), and blockage of streams (1og iams,
witerfal 'l s ) (Rei ser and Biornn 1979) .
Alaskan coho salmon enter the Alaskan gyre (a genera'l1y counter-
clockwise f1ow of water mov'ing westerly near the south side of the
Alaska Peninsula and Aleutian Islands) and travel "downstream,"
making one complete circuit per year (Morrow 1980).
Godfr6y (1965) states that the direction of movement from the high
seas oi returning North American coho salmon is not yet c1ear. It
appears, however, tfrat they enter the Gulf of Alaska in the early
sbi.i ng and summer f rom a southeasternly _di rection.- An area of
concentration bujlds up in the center of the gulf during late
June, following which the coho sa'lmon apparent'ly disperse toward
the coasts 'in many directions.
VII. FACTORS INFLUENCING POPULATIONSA. Natural
Scott and Crossman (1973) state that "coho juveniles especially
when aggregated and abundant, are preyed on by a variet_y_ of fishes
(e. g. ,
- coho smol ts , cutthroat and rai nbow trout, Do'l 'ly Varden ,
squawfi sh and scul pi ns ) , mergansers , I oons , ki ngfi shers , other
birds, and some small mammals. The adults during their spawning
run are taken by bears, other mammals, and large b'irds. In the
ocean, man, lampreys, and aquatic mammals (e.9., seals and killer
whales) are the chief predators."
266
The greatest natural mortaf ity occurs in fresh water duri.ng the
earlj life stages and is great'ly influenced by environment (Straty
1981); therefore, deleterious changes in the freshwater qualjty,
quantity, or substrate are most detrimental.B. Human-rel atedA summary of possible impacts from human-related activities
i ncl udes the fol 'l owi ng:o Alteration of preferred water temperature, PH'
oxygen, and chemical composjtion
" Alteration of preferred water volocity and deptho Alteration of preferred stream morphologyo Increase in suspended organic or mineral materialo Increase in sedimentation and reduction in permeabi'lity of
substrateo Reduction in food supplYo Reduction in protective cover (e.9., overhanging stream
banks or vegetation)o Shock waves 'in aquatic environmento Human harvest
(See the Impacts of Land and Water Use volume of this series for
additional information regarding impacts. )
VIII. LEGAL STATUSA. Managerial Authority
The Alaska Department of Fish and Game manages the fresh waters of
the state and marine waters to the 3'mi limit.
The North Pacific Fishery Management Council is composed of 15
members, ll voting and 4 nonvoting members. The 11 are div'ided as
follows: 5 from Alaska, 3 from Washington, and 3 from state
fishery agencies (Alaska, Washington, 0regon). The four nonvoting
members include the director of the Pacific Marine Fisheries
Commission, the director of the U.S. Fish and Wildlife Service,
the commander of the 175th Coast Guard Di stri ct ' and a
representat'ive from the U.S. Department of State. The council
prepares fishery management p1ans, which become law and apply to
marine areas between the 3-mi limit and the 200-mi 'limit. l,Jith
regard to salmon, the only plan prepared to date is the Salmon
Power Troll Fishery Management Plan.
The International-North Pacific Fisheries Commission (INPFC), a
convention comprised of Canada, Japan, and the United States, has
been establ i shed to provi de for sci enti fi c studi es and for
coordinating the collection, exchange, and analysis of scientific
data regarding anadromous species.
t,{ith regard to salmon, the INPFC has also prepared conservation
measures that limit the location, time, and number of fishing days
that designated high seas (beyond the 200-mi limit) areas may be
fished by Japanese nationals and fishing vessels.
di ssol ved
267
IX. LIMITATIOT{S OF INFORf,IATION
Very little life history and habitat information concerning Alaskan
cohb salmon has been co'llected/published. Most of the available
information has been documented from Pacific Northwest and Canadian
field and laboratory studies.
X. SPECIAL CONSIDERATIONS
Caution must be used when extending information from one stock of coho
salmon to another stock. Environmental cond'itions for one area must
not be treated as absolute; the stocks (races) have acclimated/evolved
over time and space to hab'itat conditions that can vary great'ly.
REFERENCES
ADEC. 1979. Water quality standards. Juneau. 34 pp.
ADF&G, comp. 1977. A comPilation offor the State of Alaska. Vol.
606 pp.
. L977a, A fish and wildlife resource inventory of the Alaska-Tn'insu'la, Aleutian Islands, and Bristol Bay areas. Vol . 2: Fisheries.
lJuneau. ] 557 pp.
Ig77b. A fish and wildl'ife inventory of the Cook Inlet-Kodiak
Vol. 2: Fjsheries. lJuneau.] 443 pp.
1978. A fish and wildlife inventory of the Prince trlilliam Sound
Vol. 2: Fisheries. [Juneau.] 24I pp.
ADF&G. 1983a. Susitna Hydro Aquatic Studies Phase
the 1982 aquatic studies and analysis of fish
ships-appendices. Anchorage. 355 pp.
. .|983b. Annual finfish management report
-fiTet.
Di v. Commer. Fi sh . , Homer. 96 pp.
fish and wildlife resource information3: Conrmercial fisheries. IJuneau.]
II report; synopsis of
and habitat relation-
- 1982 - Lower Cook
areas.
area.
I 983c . Prj nce Wi I I i am Sound area annual fi ni fsh management
report-1 983.Div. Commer. Fish., Cordova. 135 pp.
Bell, M.C. 1973. Fisheries handbook of engi-neering requirements and
biological criteria. Fisheries-Engineering Research Program Corps. of
Engineers, N. Pac. Div., Portland, 0R. Approx. 500 pp.
Bovee, K.D. 1978. Probability-of-use criteria for the family salmonidae.
instream Flow Information Paper No. 4. FWS/0BS-78/07, Ft. Colljns, C0.
Cited in Burger et al. 1983.
Brett, J.R. 1952. Temperature tolerance in. young Pacific salmon, genus
6ncorhynchus. J. Fish. Res. Bd. Can. 9(6):265'322.
268
Burger, C.8., D.B. Wangaard, R.L. l'lilmot, and A.N. Palmisano. 1983. Salmon- investigations 'in tne Kenai River, Alaska, 1979-1981. USFl^lS, Natl.
Fish. Res. Cen., Seattle; Alaska Field Station, Anchorage. 178 pp.
Burner, C.J. 1951. Characteristics of spawning nests of Columbia River
salmon. USFl.lS Fish. Bull. 61(52):97-110.
Bustard, D.R., and D.l,l. Narver. 1975. Aspects of the winter ecolog_y-of
juvenile coho salmon (0ncorhynchus kis-uqch) and steelhead trout (Sa'lmo
iairdneri). J. Fish. RAs. BAlffi Til-il-:667-680.
Chapman, D.W. 1962. Aggressive behavjor in juvenile coho salmon as a cause
of emigration. ,1.-fish. Res. Bd. Can. 19(6). Cited in Godfrey 1965.
Davis, G.E., J. Foster, D.E. Wamen, and P. Doudoroff. 1963. The influence
of oxygen concentration on the swimming performance of juvenile Pacific
salmon-at various temperatures. Trans. Rm. Fish. Soc. 92(2):L1'L-I24.
Godfrey, H. 1965. Coho salmon in offshore waters. Pages 1-40 in Salmon of
the North Pacific Ocean, Part 9. INPFC. Vancouver, Can.
Gribanov, V.I. 1948. Coho (0ncorhynchus k'isulch Walb.) (General _Biology).Izvestia TINRQ, Vo'l . 28. Transl . |r|.E. Ricker, Fish. Res. Bd. Can.,
Transl. Ser. 370. Cited in Godfrey 1965.
Ha11, J.E., and D.0. McKay. 1983. The effects of sedimentation on-salmonids and macro invertebrates: l'iterature review. ADF&G, Div.
Habitat, Anchorage. Unpubl. rept. 31 pp.
Hart, J.L. 1973. Pacific fishes of Canada. Fish Res. Bd. Can. Bull. 180.
Ottawa, Can. 739 pp.
studies in the Resurrection Bay area.
of progress 1966-1967. ADF&G, Fed. Aid
F-5-R-8, Job 7-B-1, Sport Fish Invest.
. .|968. Silver salmon studies in the Resurrect'ion Bay area. Pages
-T[-Z-tf+
in Annual report of progress .|967-.|968. ADF&G, Fed. Aid in
Fish Resil Vol. 9. Proi. F-5-R-9, Job 7-B-I, Sport Fish Invest. of
Al aska. Juneau.
. .|969. Silver salmon studies in the Resurrection Bay area. Pages
-JJT-t+g
in Annual report of progress 1978-.|969. ADF&G, Fed. Aid in
Fish Resil Vol. 10. Proi. F-9-1, Job 7-B-L, Sport Fish Invest. of
Alaska. Juneau. 383 pp.
McPhail, J.D., and C.C. Lindsey. 1970. Freshwater fishes of northwestern
Canada and Alaska. Fish. Res. Bd. Can. Bull. 173. 0ntario, Can.
381 PP.
Logan, S.M. 1967. Silver salmon
Pages 83-102 in Annual rePort
in-Fish Rest.-Vol . 8. Proi.
of Alaska. Juneau.
269
Meehan, W.R., and D.B. Siniff. 1962. A study of the downstream migrations
oi anadiomous fishes in the Taku River, Alaska. Trans. Am. Fish. Soc.
91(4):399-407.
Middleton, K.R. 1983. Bristol Bay salmon and herring fisheries status
repoit through 1982, Informational Leaflet No.zLI. ADF&G, Div.
Commer. Fish. 81 PP.
Morrow, J.E. 1980. The freshwater fishes of A'laska. Anchorage, AK: Alaska
Northwest Publishing Company. 248 pp.
Neave, F. 1943. Diurnal fluctuation in the u.ps.tream mjgration of coho and
ipring salmon. J. Fish. Res. Bd. Can. 6(2):158-163.
Netboy, A. I974. The salmon: their fight for survival. Boston: Houghton
Mifflin Company. 613 PP.
prakash, A., and D.J. Milne. 1958. Food as a factor affecting the.growth
of-coho salmon off the east and west coast of Vancouver Island, B.C.
Fish. Res. Bd. Can., prog. rept. Pacjfic Coast Sta. Lt2z7-9. Cited in
Morrow 1980.
Prjtchard, A.1., and A.L. Tester. 1944. Food of spring and coho salmon in
British Coiumbia. Fish. Res. Bd. Can. Bull. 65. 23 pp. Cited in
Scott and Crossman 1973.
Reiser, D.W., and T.C. Bjornn. Influence of forest and rangeland management
on anadromous fish habitat in western North America: habitat require-
ments of anadromous salmonids. USDA For. Serv. Gen. Tech. Rept. PNW-6'
Pacific Northwest and Range Experiment Station, Portland, 0R. 54 pp.
Russell, R.B. 1984. Personal communication. Egegik-Ugashik Area Fisheries
Mgt. Biologist, ADF&G, Div. Commer. Fish., King Sa'lmon.
Scott, W.8., and E.J. Crossman. 1973. Freshwater fishes of Canada. Fish.
Res. Bd. Can. Bull. 184. 0ttawa, Can. 966 pp.
Shaul, A. 1984. Personal communjcation. Alaska Peninsu'la-Aleutjan Islands
Area Fi sheri es Mgt. Bi o1 og'i st , ADF&G, Kod j ak.
Smith, A.K. 1973. Development and appfication of spawning velocity and
depth crjteria for '0regon salmonids. Trans. Am. Fish. Soc.
1,02(2) : 312-316.
Straty, R.R. 1981. Trans-shelf movements of Pacific salmon. Pag:s 575-595
i; D.hl. Hood and J.A. Calder, eds. The eastern Bering Sea shelf:
-oceanography and resources. Vol. 1. USDC: 0MPA' N0AA.
270
Thompson, K. 1972. Determining stream flows for fish l ife. P_ages..31-90 j-L' Proieedings, instream flow requirement workshop. Pacific Northwest
River Basin Comm., Vancouver, WA.
27r
Chum Salmon Life History and Habitat Requirements
Souttrwest and Southcentral Alasha
Map 1. Range of chum salmon (ADF&G .|978, Morrow ]980)
I.NAMEA. Common Names: Chum salmon, dog salmon, keta salmon
ketaB. Scientific Name: 0ncorhynchus
I I. RANGEA. t'lorl dwi de
Chum salmon have the widest distribution of any of the Pacific
salmon. In North America, the chum salmon ranges from the
Sacramento River in Ca]ifornia (and as far south as Del Mar, about
50 km north of the Mexican border) north to the Arctic and east at
least as far as the ltlackenzie and Anderson rivers in northern
Canada. In Asia, they range from the Lena River on the arctic
coast of Siberia east and south a'long the coast to near Pusan,
Korea, and Honshu Island, Japan. They are also found in the
273
B.
c.
Aleutian, Commander, and Kurilei islands (Morrow 1980, McPhail and
Lindsey 1970, Hart 1973).
Statewi de
Chum salmon general'ly occur throughout Alaska except for certain
streams in the Copper River drainage upstream of Miles Lake
(Roberson, pers. comm.) and in the eastern Brooks Range (Hale
1981). Relatively few streams north of the Kotzebue Sound
drainage support runs of chum salmon (ibid.).
Regional Distribution Surrnary
To supplement the distribution information presented in the text'
a seri es of b'l uel i ned reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale'
but some are at 1:1,000,000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition'
a set of colored 1:1.,000r000-sca'le index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.
1. Southwest. In the Kodi ak area , very 'l i ttl e escapement
Tnltr-mation for chum salmon is available. They utilize many
of the same streams as pink salmon for spawning (ADF&G
t977b).In the Bristol Bay area (for waters from Cape Newenham to
Cape Menshikof and north-side Alaska Peninsula streams south
to Cape Sarichef), the Nushagak, Togiak, and Naknek-Kvichak
districts are the maior producers of chum salmon (Middleton
1983). Other important runs are also found in the Egegik and
Ugashik systems (Russell, pers. comm.) and at Izembek-Moffet
llgoons, -Bechevin Bay, the Sapsuk River (Nelson Lagoon),
Herendeen Bay, Moller Bay, Frank's Lagoon, Port Heiden, and
Cinder River (Shaul, pers. corm.).
In south-side Alaska Peninsula streams, chum salmon are found
at Canoe Bay and in every other major bay east of False Pass
(ADF&G 1977a). Unga Island in South Peninsula waters is a
moderate chum salmon producer (Shaul, pers. comm.). In the
Chignik area, the Chignik Lagoon, Amber Bay, Ivanof Buy'
Kuikukta Bay, Ivan River, Kuiul ik Bay, Chiginagak Bay,
Agripina Bay, Aniakchak River, Hook Bay, and Nakali'lok River
support runs averaging several thousand fish each (Shaul 'pers. comm.). Small runs of chum salmon occur sporadically
throughout the Aleutian Islands chain, but few of these would
ever -be expected to be of commercial importance (Holmes
1984). (For more detailed narrative information, see volume
1 of the Alaska Habitat Management Guide for the Southwest
Regi on. )2. Southcentral . In the Upper Cook Inlet (UCI ) area, chum
saTlnon strrvey and escapement data are Iimited. Production
areas for chum have been identified as Chinitna Bay,
west-shore river systems of UCI, and the Susitna River (ADF&G
1982). In Lower Cook Inlet (fCt1, chum salmon production
274
areas include Port Graham, Tutka Bay, Dogfish (Koyuktolik)
Bay, Island Creek ('in Port Dick), Tonsina and C'lear creeks in
Resurrection Bay, and Port Chatham (ADF&G 198la). In
addition, all streams in the Kamishak Bay District are chum
salmon producers. They include the NcNeil, Douglas, Big
Kamishak, Little Kamishak, Bruin, and Iuiskin rivers and
Cottonwood, Sunday, and Ursus Lagoon creeks (Schroeder' pers.
comm. ).In the Prince Will'iam Sound area, chum salmon stocks exhibit
an early, middle, and late run pattern linked to geographic
distribution related to stream temperature regimes. Early
run (early and mid July) stocks spawn in maior, non-lake-fed
mainland streams of all districts. Middle-run (1ate July-
mid August) stocks spawn in lake-fed streams of the mainland
and most chum salmon streams of the outer is'land complex.
Included is these stocks are the Coghill and Duck River (in
Galena Bay) runs, which are the two largest stocks of the
middle run. fne late-run (mid August-late September) stocks
spawn almost exclusively in small spring-fed creeks at the
upper ends of Port Fidalgo and Valdez Arm (ADF&G 1978)
(For more detailed narrative information, see volume 2 of the
Alaska Habitat Managment Gu'ide for the Southcentral Region.)
III. PHYSICAL HABITAT REQUIREMENTSA. Aquatic
1 . Water qual i ty:a. Temperature. Egg hatching and alevin development have
occuffifi Alaska at temperatures ranging from 0.2 to
6.7"C during the winter months (Ha1e 1981). Optima'l
incubation temperatures, however, appear to range
between 4.4 and 13.3"C (Bell 1973).
Emergence from the gravel and downstream migration to
the sea have occurred at temperatures between 3.0 and
5.5"C; peak movements, however, occur at warmer
temperatures (i.e., 5.0 to 15"C) (Hale 1981). During
labbratory experiments, Brett (1952) found the upper
lethal temperature limit of chum salmon juveniles to be
23.8"C. Brett and Alderdice (1958) in later experiments
showed the ul timate I ower I ethal temperatures of
juveniles to be 0.1"C.
In Alaska, adult chum salmon have migrated upstream in
temperatures ranging from 4.4 to 19.4'C (Ha'le 1981) 'with peaks of migration occurring between 8.9 to 14.4"C.
Bell '(1973) sudgests water te-mperature criteria for
successful upstream migration of 8.3 to 15.6'C, with an
optimum of 10'C.
Spawn'ing has occurred in A1askan waters at temperatures
from 6.9 to 12.8'C, with preferred temperature ranges of
7.2 to 12.8'C (Hale 1981).
275
b.The pH factor. There is no optimum pH value for fish in
c.
genereT-n waters where good fish fauna occur, however,
ine pH usually ranges between 6.7 and 8.3 (Bell 1973).
State of Alaska water quality criteria for freshwater
growth and propagation of fish call for pH values of not
less than 6.5 or greater than 9.0, with variances of no
more than 0.5 pH unit from natural conditions (ADEC
1e7e).
Dissolved oxygen (D.0. ). Laboratory experiments show
ffiolved oxygen to eggs and alevinsis of critical importance because a low (less than 1
ppm) supply leads to increased mortality or delay in
hatching and/or decreased fitness (Alderdice et al.
1958). These same tests tend to indicate a slow but
steady increase in the incipient low oxygen lethal level
through development. Early stages exh'ibit a plasticity
in which development may decelerate virtual'ly to zero
under extreme hypoxial conditions. In later stages,
this plasticity is lost, and oxygen levels that would
produce no more than a cessatjon of development at
earl ier stages become rapidly lethal. The rate of
supply to the embryos and alevins is influenced
primarily by the D.0. concentration of the source water
and the rate of flow through the grave'l substrate.
Dissolved oxygen levels as low as about 2 mg/1 can meet
the oxygen requirements of eggs and alevins if the rate
of flow-of intragrave'l water is sufficient (Kogl 1965,
Levanidov 1954). Intragravel D.0. concentrations in the
Chena River during incubation of chum salmon eggs ranged
from 0.6 to 6.5 mg/l and resulted in low survival rates
at the lower concentrations and high survival rates at
the higher concentrations (Kogl 1965).
Studies concerning juvenile chum salmon dissolved oxygen
requirements summarjzed by Hale (1981) indicate lower
thresholds of 1.5 mg/l at water temperatures of 10oC.
Dissolved oxygen levels of 8 to 9 mg/1 at 8 to 10oC seem
most favorable.
Adult swinming performance can be reduced by levels of
D.0. below aii saturation (Rieser and Biornn 1979).
State of A'laska water qua'lity criteria for the growth
and propagation of fish state that "D.0. shal I be
greatbr than 7 ng/1 in waters used by anadromous and
iesident fish. Further, 'in no case shall D.0. be less
than 5 mg/l to a depth of 20 cm in the interstitial
waters of grave'l utilized by anadromous or resident fish
for spawning. In no case shall 0.0. above -17 ng/l
be permitted. The concentration of total disso'lved gas
shall not exceed lL}% of saturation at any point of
sampl e col'lectjon" (ADEc 1979) .
276
2.
d. Turbidity. Sedimentation causes high mortaf ity to eggs
;rn-d'-Eln by reducing water interchange in the redd.If 15 to 20% of the intragrave'l spaces become filled
with sediment, salmonid eggs have suffered significant
(upwards of 85%) mortality (Bell 1973). Prolonged
exposure to turbi d water causes gi 1 1 i rri tation i n
juveni 1 es that can resul t i n fungal and pathogenic
bacterial infection. Hi gh suspended sediment I oads
could be inhibiting to adults attempting an upstream
migration (Hale 1981). Exposure can lead to tail rot
and reduction of gas exchange across gi1'ls by phys'ical
damage, coating, or accumulation of mucous (Smith 1978).
Turbid water will absorb more solar radiation than clear
water and may thus indirectly raise thermal barriers to
adult upstream spawning migration (Reiser and Biorrn
1e7e).
Water quantity:a. Instream flow. Hale (1981) states, "The flow of water
InTn'e sTream channel is important to incubating embryosin promoting an adequate intragravel flow and in pro-
tecting the substrate from freezing temperatures. Heavy
mortality of embryos can occur during periods when thereis a relatively high or a relatively small discharge.
Fl oodi ng can cause h'igh morta'l 'ity by erodi ng eggs from
the redds or by depositing fine sediments on the surface
of the redds which can reduce permeability or entrap
emerging fry. Low discharge periods can lead to des-
sication of €ggS,1ow oxygen'leve1s, high temperatures,
or, during cold weather, freezing."
During laboratory tests, iuveniles when presented with a
choi ce between two channel s wi th "'lam'inar" f I ows
preferred 350, 500, 600, and 700 m'l/min flows to a flow
of 200 ml/min, and the greatest response was toward the
500 ml/min flow (Mackinnon and Hoar 1953). In another
experiment with "turbulent" water f'low, they found thatfry seemed to prefer flows of about 5'000 to 12,000
ml/min over either lesser or greater flows. Levanidov
(tSS+1 stated that optimum stream velocities to support
the feeding of fry in the Amur River, USSR' are less
than 20 cm/sec.
There is little information available on the maximum
sustained swimming ve'locity of which adult chum salmon
are capable. Chum salmon have less abifity than other
salmon to surmount obstacles (Scott and Crossman 1973)
and in general show less tendency to migrate upstream
beyond rapids and waterfalls (Neave 1966).
During spawning, chum salmon make redds in water depths
ranging from I to 120 cm (Kogel 1965). Water velocityat spawning sites has ranged from 0 to 118.9 cm/sec
(Ha1e 1981). The ADF&G (I977 ) states that optimum
277
stream flow is 10 to 100 cm/sec (presumably for spawning
and incubation).3. Substrate. Egg incubation and a'levin development occur in
su-bFtrates ranging widely in size and composition. Hale
(1981) sunmarizes redd sites by stating that, "in general,
chum salmon excavate redds in gravel beds with a particle
size of 2 to 4 cm diameter, but they will also construct
redds in substrates with partic'les of a greater size and will
even use bedrock covered with small boulders (Morrow 1980,
Scott and Crossman 1973) . General ly, substrates wi th a
percentage of fine particles (1ess than 0.833 nm in diameter)
greater than 13% are of poor quality because of reduced
permeabil ity (Thorsteinson 1965). Chum salmon, however,
often spawn in areas of upwelling ground water and may
therefore be able to to'lerate higher percentages of fines
than would seem desirable if some of the fines are kept in
suspension by the upwel 1 ing water. " The ADF&G (L977)
observed that spawning usually occurs in riffle areas and
that chum salmon generally avoid areas where there is poor
circulation of water through the stream bed.B. Terrestrial1. Condit'ions providin rt
FEreanrslch-um salmon juveniles m'igrate mainly at night and
seek cover in the substrate during the daytime if the journey
is not completed in one night (Neave 1955). Hoar (tSSO1
found that chum salmon f"y, after schoo'ling has occurred
during downstream migration, use the protection of schools
during day'l ight and no longer seek protection in the
substrate.2. Condi!ions providing Jrotectjon from natural elements. Ag ionsof alevins reared at lz"C and water velocities of 100cm/hr
(Emadi 1973). Alev'ins reared on a smooth substrate with
identical temperature and water velocities were susceptible
to yolk sac malformation. Since alevins prefer to maintain
an upright pos'ition, which is difficult on a flat surface,
the swimming activity to right themselves results in
continual rubbing on the flat surface, wh'ich is thought to
i njure the yo] k and cause mal formati on ( i b j d. ) .
IV. NUTRITIONAL REQUIREMENTSA. Food Species Used
Upon hatching, young alevin remain in the gravel for.30 to 50 daysuntil their yolk sacs are absorbed (Bakka'la 1970). Most chum
salmon juveniles begin their downstream migration to the sea soon
after emergence. Young chum salmon with on'ly a short distance to
travel probably do not feed until they reach the ocean (Morrow
1980). Those that must spend several days to weeks on their
journey, however, feed actively on chironomid larvae, cladoceans
278
V.
(water fleas), copepods, nematodes, and a variety of mature and
immature insects (Norrow 1980, Scott and Crossman 1973).
During their early sea life they feed on a wide variety of
organisms, such is diatoms, many small crustaceans (e.9.,
chaetognaths, ostracods, cirripedsn mysids, cumaceans''isopods,
amphipods, decapods), dipterous insects, and fish Iarvae.
Copepods, tunicates, and euphasiids . dominate the djet at sea
(Morrow 1980, Scott and Crossman 1973). 0ther items eaten at sea
include other fishes, pteropods, squid, and mullusks.
B. Types of Feeding Areas Used
Bbtause chum salmon spend such a Short time in natal water fol-
lowing emergence from the gravel, no data are availab1e on fresh-
water feeding locations. At sea, the fish are found from close to
the surface town to at least 61 m. There is some indication of
vertical movement accord'ing to the t'ime of day, with the fjsh
tending to go toward the surface at night and deeper during thq
day (Manzer 1964). This is probably a response to movements of
food organisms (Morrow 1980).C. Factors Limiting Availability of Food
Chum salmon juv-eniles that feed while in fresh water eat benthic
organisms. Excessive sed'imentation mqy inhibit product'ion of
aqiatic plants and invertebrate fauna (Hall and McKay 1983) and
thereby decrease available food.D. Feeding Behavior
Juvenile daily food intake while in fresh water increases as water
temperatures increase. Levanidov (1955), using aquaria, found
that at 4 to 10"C the weight of food eaten da'ily was 5 to 10% of
the body weight; at LZ to 20"C it was 10 to 19% of the body
weight. Juveniles appear to be benthic feeders, rely'ing on
aquitic insects to supply the bulk of the'ir food (Bakkala 1970).
Adult feeding seems to be opportunistic and is based on availa-
bility of, rither than preference for, certain kinds of food (Le
Brass-eur 1966). Upon returning to fresh water to spawn, adults
cease feeding and obtain energy from body fat and protein (Morrow
1980, Bakkala 1980).
REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat
Chum salmon spawn jn waters ranging from short coastal streams,
where the adults may spawn within the tjdal zone, to large river
systems, such aS the Yukon River, where they are known to migrate
upstream over 2,500 km. Most, however, spawn above the reaches of
salt water and within 200 km of the sea (gakkata 1970). Spawning
grounds must provide suitable substrate as well as suitable stream
ionditions. Many stocks of chum salmon (part'icularly fall chum)
select areas with springwater or ground water emergence. These
areas tend to maintain water flows and temperatures warm enough to
keep from freezing during the winter months (Morrow 1980' Hale
1e81 ) .
279
B.
c.
Reproducti ve Seasonal i ty
The chum salmon is typical'ly a fall spawner. In Alaska, they
ascend the rivers from June to September, the peak spawning for
northern popu'lations occuring from July to early September and for
southern populations in 0ctober or November (Morrow 1980, Ha'le
1981). 0n the Alaska Peninsula, spawning occurs from August to
early September (Shaul, pers. comm.).
Reproductive Behavior
As with other salmon, adult chum salmon return from the sea and
move into their natal freshwater streams to spawn. The female
selects the spawning site and digs the redd (nest) by turning on
her side and thrashing her tail up and down. The current washes'loose redd substrate materjal downstream, and a depression 8 to 43
cm deep is formed in the river bottom (Burner 1951, Bakkala 1970).
Eggs and sperm (milt) are released simultaneously and deposited in
the redd. After egg deposition, the female moves to the upstream
margin of the redd and repeats the digging process. Dislodged
substrate is washed over the eggs. In this manner, the eggs are
covered and prevented from washing away. The process is repeated,
and the redd appears to move upstream (Burner 1951). As a result
of the continued digging, the redd may grow to become 1.6 to 3.2n
'f ong and 1.1 to 2.I m wide (Bakkala 1970). A female may spawn
with several males, and a male may mate with more than one female
(Morrow 1980).
Age at Sexual Maturity
The age at which chum salmon mature sexua'l'ly ranges from two to
seven years, although most mature in their third to fifth year.
In general, fish from the southern part of the range return to
streams during their third and fourth years, whereas those from
the Yukon (and probably other far north rivers) return mostly intheir fourth and fifth years (Bakkala 1970, Morrow 1980). In
A'laska Peninsula waters, fourth-year chum salmon are normally
predominant, fol lowed by significant numbers of third and
fifth-year fish (Shau1, pers. comm.). Fish in their fourth year
are usually most common in Southeast Alaska. Fifth-year fish
predominate from Prince l,'Jjlliam Sound northward, with fourth and
sixth-year fish being next in abundance. Seventh and eighth-yearfish are rare (Hale 1981).
Fecundi ty
Fecund'ity varies by stock and the size
from 1,000 to 8,000 eggs. In Alaska,
common (ibid.).
of the female and ranges
2,000 to 3,000 are most
Frequency of Breeding
As with all Pacific salmon, the spawning cycle for chum salmon is
terminal. Both male and female die after spawning.
Incubati on Peri odlEmergence
The time required for eggs to hatch is dependent upon many
interrelated factors, including 1) di ssolved oxygen , 2) water
temperature, 3) apparent velocity in grave'l , 4) bio'logical oxygen
demand, 5) substrate size (limited by percentage of small fine
material), 6) channel gradient and 7) configuration, 8) water
D.
E.
F.
G.
280
depth, 9) surface water discharge and velocity, 10) permeability,
11) porosity, and 12) light (Reiser and Bjornn 1979, Hale 1981).
General'ly speaking, factors 4 through 12 influence/regulate the
key factors 1, 2, and 3.
The time from fertilization to hatching can range from 1.5 to 4.5
months, depending primarily on water temperature. In Alaska,
hatching of eggs occurs from December to February in the southerly
parts of the range. The time of hatching in interior and northern
Alaska is not definitely known. The alevins remain in the gravel
until the yolk sac is absorbed, 60 to 90 days after hatching, then
make their way through the gravel and begin migration to the sea
(Morrow 1980). Although rare, chum salmon that have spent at
least a year in freshwater lakes and grown to lengths of 160 to
I70 mm have been captured at Lake A'l eknagi k 'in the Wood Ri ver
system of Bristol Bay (Roberson, pers. comm.).
VI. MOVEMENTS ASSOCIATED l,lITH LIFE FUNCTIONSA. Sizes of Use Areas
From studies of Columbia River tributaries, Burner (1951) suggests
that a conservative figure for the number of pairs of salmon that
can satisfactorily utilize a given area of spawning gravel may be
obtained by dividing the area by four times the average size of
the redds. Redd area can be computed by measuring the total'length of the redd (upper edge of pit to lower edge of tailspill)
and the average of several equidistant widths (Reiser and Bjorrn
197e).
The average size of the redd area has been reported to range from
1.0 m2 to 4.5 m2 (Ha'le 1981). The ADF&G (1977) states that the
optimum size is considered to be 3 m2.B. Timing of Movements and Use of Areas
Soon after emerging from the gravel, juvenile chum salmon begin
moving to the sea. Downstream migration is usually at night near
the surface of the water and in the center of the stream, where
the currents are strongest. When the migrations cannot be made in
one night, the young fish hide in the gravel by day (Bakkala 1970,
Scott and Crossman 1973, Hunter 1959).
In their first year at sea, chum salmon migrate to offshore waters
of the North Pacific 0cean and Bering Sea.
Adults return to fresh water during the period from June through
September. Rates of movement during upstream migration varygreat'ly. Bakal I a (1970) gi ves the fo'l l owi ng exampl es : "Yukon
River chum salmon migrated at 80 km per day for the first 1.,300 km
and 56 km per day for the next 1,100 km. In the Amur River, USSR,
the average rate of migration was 115 km per day. In some rivers
of Japan where spawning grounds are much closer to the sea, the
average rate of travel was 1.9 to 4.2 km per day."C. Migration Routes
Rivers serve as corridors for smolt outmigration. Adult upstream
migration may be hindered or prevented by excess turbidity, high
temperatures (20.0'C or more), sustained high water velocities
28r
(greater than 2.44mlsec), and blockage.of streams (e.9., 1og jams
and waterfalls) (Reiser and Bjornn 1979).
Qnce in the sea, the young chum salmon remain c'lose to shore
(within 37 to 55 km of the shoreline) during Ju1y,. August, and
September before dispersing into the open ocean_ (Morrow 1980,
Neive et al. 1976). During this time, stocks found along the
northern coast of the Gulf of Alaska and south of the Alaska
Peninsula probably migrate westward. Stocks found north of the
A'laska Pen'insula - prob-ab1y move to the southwest (Neave et al.
1e76).
From tagging studies, Neave et al. (1976) summarize maturing-
Alaskan -cnum salmon movements as follows: "Maturing chums of
western Alaskan origin occupy the entire Gulf of Alaska'in spring
and were found westward along the Aleut'ians to I79"E. There was
no tagging evidence of the presence of Alaskan chums in the Bering
Sea before June. The recovery in the Yukon River of a maturing
fish tagged in July at 60oN, 174"E, not far from the U.S.S.R.
coast, constitutes the westernmost record of a north American chum
salmon, as revealed by tagging. Other chums, tagged in the Gulf
of Alaska, were found to travel as far north as the Arctjc Ocean.
The direction of movement in the Gulf of Alaska is westward in
April-June. In the latter month most of the fish pass through the
eastern part of the Aleutian Chain and mjgrate rapid'ly northward
in the Bering Sea. No significant penetrat'ion of the Bering Sea
by immature fish was disclosed.
Maturi ng chum salmon ori gi nati ng i n central and southeastern
Alaska occupy a large part of the Gulf of Alaska in spring but
were rare'ly found west of 155't^l. From May to July the f ish tend
to shift northward into waters from which western Alaska chums
have large'ly withdrawn. Some immature fish move westward along
the A1 euti ans to at I east 177"W. No s'i gn'i f i cant penetrati on of
the Bering Sea by immature or maturing fish was indicated."
VII. FACTORS INFLUENCING POPULATIONSA. Natural
The period the eggs and alevin spend in the gravel is a time of
heavy mortality. The survival rate from eggs to fry in natural
streams averages less than I0% (Hale 1981).
Scott and Crossman (1973) state that "young chum sa'lmon on the
spawning grounds and during downstream m'igrat'ion are _preyed upon
by cutthroat and rajnbow trout, Do11y Varden, coho salmon smolts,
squawf i sh, and scul pi ns. Kingfi sher, merganser, other
predaceous birds, and marnmals are also responsible for a smallloss. Even stonefly larvae and possibly other predaceous insects
may prey on eggs and al evi ns . Water temperature, fl oods 'droughts, other fluctuations in water level, spawning competion,
and poor returns of adults, control number of young to a far
greater extent." At sea, chum salmon are preyed upon by_man'
marine manmals, lampreys, and, in the early sea life, possibly by
large fishes. Upon returning to fresh water to spawn, adults fall
282
prey to bears, eagles, osprey, and other manrnal s (Scott and
Crossman 1973).B. Human-rel atedA summary of possible impacts from human-related activities
i nc'ludes the fol l owi ng:o Alteration of preferred water temperatures, pH, dissolved
oxygen, and chemical composition
" Alteration of preferred water velocity and deptho Alteration of preferred stream morphology
" Increase in suspended organic or mineral materialo Increase in sedimentat'ion and reduction in permeability of
substrateo Reduction in food suPPlYo Reduction in protective cover (e.9., overhanging stream banks
or vegetation)" Shock waves in aquatic environment
" Human harvest
(For additional impacts information see the Impacts of Land and
Water Use volume of this series.)
VIII. LEGAL STATUSA. Managerial Authority
The Alaska Department of Fish and Game manages fresh waters of the
state and marine waters to the 3-mi limit.
The North Pacific F'ishery Management Council is composed of 15
members, 11 voting and 4 nonvoting members. The 11 are divided as
follows: 5 from Alaska, 3 from Washington, and 3 from state
fishery agencies (A1aska, t^lashington, 0regon). The four nonvoting
members include the director of the Pacific Marine Fisheries
Commission, the director of the U.S. Fjsh and hlildlife Serv'ice,
the commander of the 17th Coast Guard Di strict ' and a
representative from the U.S. Department of State. The council
prepares fishery managment plans that become federal law and apply
to marine areas between the 3-mi limit and the 200-mi limit. With
regard to salmon, the only plan prepared to date is the Salmon
Power Troll Fishery Management Plan.
The International North Pacific Fisheries Conrnission is a
convention comprised of Canada, Japan, and the United States
established to provide for scientific studies and for coordinating
the col lection, exchange, and analysis of scientific data
regarding anadromous species.
With regard to salmon, the INPFC has also prepared conservat'ion
measures that limit the location, time, and number of fishing days
that designated high seas (beyond the 200-mi limit) areas may be
fished by Japanese nationals and fishing vessels.
IX. LIMITATIONS OF INFORMATION
Limited life history and habitat informat'ion concerning Alaskan chum
salmon has been co1 'lected/publ i shed. Most of the avai I abl e i nformation
283
has been documented from Pacific Northwest and Canadian field and
laboratory studies.
X. SPECIAL CONSIDERATIONS
Caution must be used when extending information from one stock of chum
salmon to another stock. Environmenta'l conditions from one area must
not be treated as absolute; the stocks (races) have acclimated/evolved
over time and space to habitat condjtions that can vary great'ly.
The distribution and abundance narrative for the salmon species 'presented by ADF&G commercial fisheries management areas, fo1'lows the
aggregated salmon life histories.
RE FERENCES
ADEC. 1979. Water quality standards. Juneau. 34 pp.
ADF&G, comp. 1.977. A compilation of fish and wildlife resource informationior ftre State of Al'aska. Vol . 3: Commercial fisheries. IJuneau.]
606 PP.
. 1977a. A fish and wildlife resource inventory of the Alaska
Tninsula, Aleutian Islands, and Bristol Bay areas. Vol . 2: Fisheries.
lJuneau.] 557 pp.
areas.
1977b. A f i sh and wi l dl 'i fe 'i nventory of the Cook Inl et-Kodi ak
Vol. 2z Fisheries. [Juneau.] 443 pp.
. 1978. A fish and wildlife resource inventory of the Prince
-ln'laim Sound area. Vol . 2: Fisheries. [Juneau.] 24I pp,
ADF&G. 1981. Lower Cook Inlet annual management report: salmon. ADF&G'
Div. Conrmer. Fish., Homer. 97 PP.
. 1982. Stock separation feasibi'l ity report. Phase 1: Final--Tratt. ADF&G, Su-Hydro Adult Anadromous Fisheries Project, Anchorage.
74 pp.
Alderdice, D.F., t,l.P. Wickett, and J.R. Brett. 1958. Some effects of
temporary exposure to low dissolved oxygen levels on Pacific salmon
eggs. J. Fjsh. Res. Bd. Can. 15(2):229-259.
Bakkala, R.G. 1970. Synopsis of biologica'l data on the chum salmon,
0ncorhynchus keta (Walbaum)-1792. FAO Species Sy_n-opsis No. 41. USFI,JS,
ffih., circular 315. Wash., DC. 89 pp.
Bell, M.C. 1973. Fisheries handbook of engineering requirements and
bio'logica'l criteria. Fisherjes-Engineering Research Program, Corps of
Engineers, North Pacific Division. Portland, 0R. Approx. 500 pp.
284
Brett, J.R. 1952. Temperature tolerance in young Pacific salmon, genus
Oncorhynchus. J. Fish. Res. Bd. Can. 9(6)z?65-322.
Brett, J.R., and D.F. Alderice. 1958. The resistance of cultured ltou!9
chum and sockeye salmon to temperatures below zero degrees C. J. Fish.
Res. Bd. Can. 15(5):805-813. Cited in Hale 1981.
Burner, C.J. 1951. Characterjstics of spawning nests of Columbia River
salmon. USFl'lS Fish. Bull. 61(52):97-110.
Emadi, H. 1973. Yolk-sac malformat'ion in Pacific salmon in relation to
substrate, temperature, and water velocity. J. Fish. Res. Bd. Can.
30(B) :I,249-I,250.
Hale, S.S. 1981. Freshwater
hynchus keta). ADF&G,
Anchorage. 81 pp.
habitat relationships: chum salmon
Di v. Habi tat, Resource Assessment
(0ncor-
Branch,
Hal1, J.E., and D.0. McKay. 1983. The effects of sedimentation on
salmonids and macro invertebrates: I iterature review. ADF&G, Div.
Habitat, Anchorage. Unpubl. rept. 31 pp.
Hart, J.L. 1973. Pacific fishes of Canada. Fish. Res. Bd. Can. Bull. 180.
0ttawa, Can. 739 pp.
Hoar, W.S. 1956. The behavjor of migrating pink and chum salmon fry.
J. Fish. Res. Bd. Can. 13(3):309-325.
Hunter, J.G. 1959. Survival and production of pink and chum salmon in a
coastal stream. J. Fish. Res. Bd. Can. 16(6):835-886. Cited in Hale
1981.
Kogl , D.R. 1965. Springs and ground-water as factors affecting surv'iva'l of- chum salmon spawn in a sub-arctic stream. M.S. Thesis, Univ. Alaska'
Fairbanks. 59 pp. Cjted in Hale 1981.
LeBrasseur, R.J. 1966. Stomach contents of salmon and steelhead trout in
the northeastern Pacific 0cean. J. Fish. Res. Bd. Can. 23:85-100.
Cited in Bakkala 1970.
Levanidov, V.Y. 1954. Ways of increasing the reproduction of Amur chum
salmon. (Transl. from
I khti o'l ogi cheskaya Komi ssya ,
Prog. Sci. Transl. Cat. No.
12 pp. Cited in Hale 1981.
Russian. ) Akademiya. Nauk USSR,
Trudy Soveschanii, No. 42120-128. Israel8. Office of Tech. Serv., USDC, Wash., DC.
. 1955. Food and growth of young chum salmon in fresh water.----ooT. 7h. 34:37L-379 Transl. Fjsh. Res. Bd. Can. Biol . Sta., Nanaimo,
Brit. Col. Transl. Ser. 77. Cited in Bakkala 1970.
285
Levanidov, V.Y., and I.M. Levanidova. 1951. The food
salmon in fresh water. (Transl. from Russian).
I ss'l ed. I nst. Ryb. Khoz . Okeanog. 35: 41-46.
Transl. Ser. I02. Cited in Hale 1981.
of young Amur chumIzv. Tikh. Nauch. -
Fish. Res. Bd. Can.
MacKinnon, D., and l'l.S. Hoar. 1953. Responses of coho and chum salmon fry
to current. J. Fish. Res. Bd. Can. 10(8):523-538. Cited in Hale 1981.
Manzer, J.l. 1964. Pre'liminary observations on the vertical distribution
of Pacific salmon (Genus 0ncorhynchus) in the Gulf of Alaska. J. Fish.
Res. Bd. Can. 21(5):891-90I--ffiin Morrow 1980.
Middleton, K.R. 1983. Bristol Bay salmon and herring fisheries status
report through 1982. Informational Leaflet No.zLI. ADF&G, Div.
Cormer. Fish., Homer. 81 pp.
McPhail, J.D., and C.C. Lindsey. 1970. Freshwater fishes of northwestern
Canada and Alaska. Fish Res. Bd. Can. Bull. I73. 0ntario, Can. 381
pp.
Morrow, J.E. 1980. The freshwater fishes of Alaska. Anchorage, AK: A1aska
Northwest Publishing Company. 248 pp.
Neave, F. 1955. Notes on the seaward migration of pink and chum salmon
fry. J. Fish. Res. Bd. Can. 12(3):369-374. Cited in Hale 1981.
. 1966. Salmon of the North Pacific 0cean: Part 3. INPFC Bull.18.
Tcouver, B.C. Can.
Neave, F., T. Yonemori, and R.G. Bakkala. 1976. Distribution and origin of
chum salmon in offshore waters of the North Pacific Ocean. INPFC Bull.
35. Vancouver, Can. 79 pp.
Reiser, D.W., and T.C. Bjornn . 7979. Influence of forest and rangeland
management on anadromous fi sh habi tat i n western North America:
habjtat requirements of anadromous salmonids. USDA Forest Service Gen.
Tech. Rept. PNW-6. Pacific Northwest Forest and Range Experiment
Station, Portland, 0R. 54 PP.
Roberson, K. .|985. Personal communication. Research Project Leader,
ADF&G, Glennallen.
Schroeder, T. 1985. Personal corrnunication. LCI Area Mgt. Biologist,
ADF&G, Div. Commer. Fish., Homer.
Scott, t'l.B., and E.J. Crossman. 7973. Freshwater fishes of Canada. Fish.
Res. Bd. Can. Bull. 184. Ottawa, Can. 966 pp.
Shaul, A. 1984. Persona'l communication. Alaska Peninsula-Aleutian Island
Area Fisheries Mgt. Biologist, Div. Cormer. Fish., ADF&G, Kodiak.
286
Smith, D.W. L978. Tolerance of juvenile chum salmon (0ncorhynchus keta) to
iuspended sediments. M.S. Thesis, Univ. Wash.reaiile. W pp.
Cited in Hale 1981.
Straty, R.R. 1981. Trans-shelf movements of Pacific sa'lmon. Pages 575-595
in W.D. Head and J.A. Calder, eds. The eastern Bering Sea shelf:
6Eeanography and resources. Vol. I. USDC: NOAA, 0MPA.
Thorsteinson, F.V. 1965. Effects of the Alaska earthquake on pink and chum
salmon runs in Prince William Sound. Pages 267-280 in G. Dah'lgren, €d.
Science in Alaska, 1964. Proceedings of the 15th Alaska science
conference. AAAS, College, AK. Cited in Hale 1981.
287
Pinh Salmon Life History and Habitat Requirements
Souttrrest and Southcentral Alasha
Map 1. Range of pink salmon (ADF&G 1978, Morrow 1980)
I. NAMEA. Corrnon Names: Pink salmon, pinks, humpback sa1mon, humpyB. Scientific Name: Oncorhynchus gorbuscha
I I. RANGEA. Wor'ldwi de
Pink salmon are the most abundant of the Pacific salmon (Krueger
1981). In North America, pink salmon range from the Russian
River, California, north through the Bering Strait, and east tothe Mackenzie River in the Northwest Territories, Canada. In
Asia, pink salmon occur from the Tumen and North Nandai rivers of
North Korea and the island of Hokkaido, Japan, north to the Lena
River, Siberia. They also occur in the Kurile, Cormander, and
Aleutian is'lands (Neave 1967).
289
B.Statewi de
Pink sa'lmon are wide'ly distributed along coastal A'laska, with on'ly
a few in the Copper River delta and none in the upper Copper River
drai nage (ADF&G. 1978; Roberson, pers. comm. ) . _ They typical 1y
ascend- streams on'ly short d'istances (65 km or I ess ) , an.d sgme
spawn in the interijdal areas of short coasta'l streams (Bailey
1969, Scott and Crossman 1973). In larger river systems s.uch as
the Kuskokwim and Yukon some may go as much as 160 km (Morrow
1980). They are known to move great distances in the Nushagak
River drainlge. Measuring from Picnic Point at the Wood River
confl uence wi ttr the Nushagak Rj ver, pi nk salmon have been
documented about 230 km upstream in the Nuyakuk River and
approximately 410 km upstream'in the Mulchatna River (APF&G 1984).
Rblent studies on the Susitna River in Southcentral Alaska have
found spawning pink salmon at least 223 km upstream (ADF&G 1981).
Regional Distribution SunrnarY
To-supplement the djstributjon information presented jn the text'
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale,
bul some are at 1:1,000,000 scale. These maps are avai'lable for
review in ADF&G offices of the region or may be purchased from the
contract Vendor responsible for their reproduction. In addition'
a set of colored 1:1,000,000-scale index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.
1. Southwest. In the -Kodiak area, there are approximately 300
ieanrs Itrat produce pink salmon, although 60 to 85'/" of the
total escapement is usually contained in 35 major river
systems during odd-numbered years and in 47 of the maior
river systems -during even-numbered years (Prokopowich, pers.
conrm.). These systems comprise the Kodiak arears index
streams.In the Bristol Bay area (for waters from cape Newenham to
Cape Menshikof and north-side Alaska Peninsula streams south
to Cape Sarichef), the Nushagak District is the -major pink
salmon producer. Within the district, pink sa'lmon spawn
almost entire]y in the Nuyakuk River, with smal ler
populations also found in the Wood, Igushik, Nushagak, and
Muichatna rivers. 0ccasiona'11y, strong runs occur in the
Kvichak, Alagnak (Branch), ana Naknek rivers (Middleton
1983). Bechevin Bay streams occasionally produce strong pink
salmon runs during even-numbered years (Shaul' pers. cgmn.).
In south-side Alaska Peninsula streams and the Aleutian
Islands, pink salmon are abundant and are found in many
drainages.' In the Chignik area, there are approximate-1y 75
salmon- streams. In the south peninsula area, Mino Creek,
Settlement Point, and Southern Creek on Deer Is'land
occasionally produce one-half the total pink salmon run to
the area. fwb other streams (Apollo Creek and Midd'le Creek)
have the combined potentia'l of producing another 500'000 to
c.
290
2 million pink salmon in a good year, if waterfalls on these
streams coul d be bypassed wi th fi sh-passage structures(iUiA.1. (For more detailed narrative informatjon' see
vo'lume 1 of the Alaska Habjtat Management Guide for the
Southwest Reg'ion. )?.. Southcentral. In the Northern and Central districts of the
nppE7-TiFtn'let area the maiority of the_ pink salmon are
prbduced in the Lake Creek, Deshka, Talachulitna, Kenai, and
Kasilof river drainages (ADF&G I977b). In the Southern,
0uter, and Kamishak districts of the Lower Cook Inlet area,
the majority of the pink salmon are produced in the fo'llowing
locations: Humpy Creek, Tutka Lagoon, Seldovia Creek, Port
Graham River, Wjndy Left River, Windy Right River' Rocky
River, Port Dick Creek, Bruin Bay River, Big Kamishak River,
Little Kamishak River, Amekedori Creek, Sunday Creek, and
Brown's Peak Creek (ADF&G 1981a).In Prince William Sound (PWS), the genetica'l1y unrelated
odd-year and even-year pi nk salmon stocks have adapted
diffbrent'ly to the use of the same spawning streams. The
odd-year stocks use primarily upstream spawning sites' with
43 to 65% (average of 25.6%) selecting spawning sites above
the high tide line, while even-year stocks are more oriented
toward intertidal spawning areas, with only 23 to 28%
(average of 25.6%) selecting spawning sites above h'igh tide.
hlith regard to spawning areas, PhlS pink salmon may be
generally catagorized as early, middle, and late spawning
stocks, which are distributed by geographic zones associatedwith different temperature regimes. Ear'ly runs (about
July 20 to August 5) are found i n re'lati ve'ly few streams ,
primarily in the major fjords of the northern main land, Port
Wel'ls, Valdez Arm, Port Fidalgo, Port Gravina, and Sheep Bay.
Middle runs (about August 6 to August 20) utilized most of
the larger, cold, clear streams of the mainland districts and
a few cbld mountain streams of Knight and LaTouche islands.
Late runs (about August 2I to September 10)occupy the
majorjty of the streams used and include near'ly all the
i sl and streams , mai nl and 'l ake-fed streams , and mai nl and
streams in wh'ich on'ly intertidal zones are accessible to
migrants (ADF&G 1978).
(For more detailed narrative information, see volume 2 of the
Alaska Habitat Management Guide for the Southcentral Region.)
III. PHYSICAL HABITAT REQUIREMENTSA. Aquatic
1 . Water qual i ty:a. Temperature. Pink salmon in Southeast Alaska have been
o5serveilE spawn 'in water temperatures ranging from 7.4
to 18.3"C (Sheridan 1962). The preferred range appears
to be 7.2 to 12.8"C (Krueger 1981).
29t
b.
c.
Egg hatching rates are influenced by w_ater temperature;
abnormal'ly warm or co'ld water can accelerate or depress
developmental rates and cause premature or delayed fry
emergence. Laboratory tests have shown that e99s
require at least 4.5oC water temperatures from the time
thd egg is deposited in the redd through the ga!!I!]a
stage of d6ve'lopment (Bailey and Evans 1971).
Thereafter, the embryos can tolerate water temperatures
to 0'C if the water does not freeze. The upper lethal
temperature limit for pink salmon. juveniles.was experi-
menlally determined to be 23.9"C (Brett 1952), but ]ower
lethal - limits were not determined. Brett found'
however, that iuveniles preferred 12 to 14"C
temperatures.
The'pH factor. There is no optimum pH value for fish in
@ffiTf-h6tEver, in waters where good fish fauna occur'
ltre pH usua'l1y ranges between 6.7- and 8.3 (8e11 1973) .
State of Alaska water quality criteria for freshwater
growth and propagation of fish ca1'l for pH values of not
less than 6.5 or greater than 9.0, with variances of no
more than 0.5 pti unit from natural conditions (ADEC
197e ) .
Dissolved oxygen (D.0.). From laboratory experiments'
recornmend that for successful
development of pink salmon eggs and alevins the D.0.
level should exceed 6.0 mg/.|. Dissolved oxygen levels
below 6.0 ng/1 apparent'ly cause premature emergence'
decreased siie, and low survival (ib'id.).
State of Alaska water quality criteria for growth and
propagation of fish state that "D.0. shalI be greater
ttrah 7 mg/l in waters used by anadromous and resident
fjsh. Further, in no case shall D.0. be less than 5
mg/l to a depth of 20 cm in the interstitial waters of
giavel utilized by anadromous or resident fish for
ipawning In no case shall D.0. above 17 ng/1 be
permi ttAd. The concentrati on of tota'l di ssol ved gas-
lfratt not exceed Il0% of saturation at any point of
samp'le collection" (ibid. ).Turbidity. Sedimentation causes h'igh mortality to eggs
anilaTeiin by reducing water interchange in the redd.
If 15 to ?O% of the intragravel spaces become filled
with sediment, salmonojd eggs have suffered significant
(upwards of 85%) mortal ity (get t 1973). Prolonged
exilosure to turbid water causes 9i11 irritation in
juveniles, which can resu'lt in fungal and pathogenic
bacterial infection. Excess turbidity from organic
materials in the process of oxidation may reduce oxygen
below safe levels, and sedimentat'ion may smother food
organisms and reduce primary productivity (ibid. ).
tuiUid water will absorb more solar radiation than clear
d.
292
2.
water and may thus indirect'ly raise thermal barriers to
the adul t' s upstream spawni ng mi grati on ( Rei ser and
Bjornn 1979).
Water quantity:
a. Instream flow. Sufficjent water velocity and depth are
neffilT- al I ow proper i ntragrave'l water movement
(apparent velocity) so that dissolved oxygen js trans-
ported to eggs and alevin, and in turn metaboljc wastes
are removed ( ibid. ).
Adults returning to spawning grounds may be blocked if
current velocities exceed 2.1 m/sec (Krueger 1981). Low
flows and shallow water depths can also block upstream
migration. Thompson (1972) suggests that adult. p'ink
saTmon need a minjmum of about 0.18 m water depth for
upstream passage. These values will vary with the size
aha condi'tion -of adult pink salmon and the length of
stream reach with shallow water (Krueger 1981). Pink
salmon have been observed passing over shallow riffles
less than 0.09 m deep in the Kizhuyak and Terror rivers
on Kodiak Island (galdridge, pers. comm. cited in
Krueger 1981).
tJatei velocity at spawning locations has ranged from 0.1
to I.32 m/sel, and the preferred range appears to be
about 0.35 to 0.75 m/sec (Krueger 1981). Depth at redds
has ranged from 0.1 to 1.32 m, with preferred depths
ranging-from 0.39 to 0.70 m (ibid.). Use of waters
outside the preferred ranges may in large part be due to
crowding on the spawning grounds.
Substrate. Pink salmon spawn over a variety of substrates
ranglng widely in size and composition. Adults generally
sel6ct-areas -with a relatively low gradient combined with
beds of small-to-medjum-size giavel (i.3 to 10 cm diameter)
(Neave 1966, Scott and Crossman 1979, Krueger 1981).
Egg and alevin development is jnfluenced b.y_ substrate
composition because increased amounts of smal I material
(fihes) can reduce intragravel water flow. McNeil and Ahnell
(1964), from studies in Southeast Alaska, concluded that
producti ve pi nk salmon streams genera'l 1y conta'ined f i nes
iO.gSS mm diameter) contributing less than 5% of the volume
of the substrate. They also found that'less productive
streams were characterized by 15% or more fines in the
substrate.
Terrestri al1. Conditions providinq security from other predalqrs or
AiE[FFance caused by ice and floods. It also protects the
eggs from sun'light and predation by other fish and aquatic
i nsects.2. Conditions providinq protection from natural elements.t
3.
B.
293
time after emergence from the substrate, lto data are
available concerning protection from natural elements for
free-swimmi ng juveni I es.
IV. NUTRITIONAL REQUIREMENTSA. Food Species Used
Upon hatching, young alevin remain in the grave'l f_or several weeks
until the yolk sac has been absorbed. Immediately upon emerging
from the giavel, juveniles begin migrating downstream (Scott and
Crossman 1973). Migrating juveniles generally do not feed; if the
distance to the sea is great, however, they may feed on nymphal
and larval insects (ibid.). Studies in Lake Aleknagik and Tikchik
Lake jn the Bristol Bay area, however, indicate differences in the
early life history of pink salmon that spawn in a lake systery frq[
those that spawn in coastal rivers. Rogers and Burgner (1967)
state that "in coastal rivers, the fry m'igrate to salt water upon
emergence from the gravel. They area then about 30 rnm 1ong. Thq
young fry obtain little food from the freshwater environment and
subsist largely on the yo'lk. In the Wood River lakes and Tikchik
Lake, the fry must travel some distance to reach the outlet rivers
(96 km in itre case of Agulukpak River fry); and it is quite
apparent that they feed actively during the- course of their
ti^avel." In addjtion, jt was found that some of the juvenile pink
salmon remained in Lake A'leknagik long after emergence, were
caught in tow net samples as late as September 10, and had grown
to mean lengths of 89 mm (ibid.). An examination of stomach
contents taken from Lake Aleknagik fry during July 1-8' 1967'
revealed that zooplankton (i.e., Bosmina, Daphnia, t!.olopedium.'
Cyc'lopoida, and Caianojda) made up tTe 6uTk ofTh-e foodTibitF
In nearshore salt water, the juveniles consume small crustaceans(e.g., copepods, euphasiids, amphipods, ostracods), larvae of
decipoas,'cirripedes' and tunicates, and dipterous insects (Neave
1966). As they grow, the diet consists of larger items until,
during their final summer in the high seas, the diet consists of
many organisms, the most important being euphasjids, amphipods,
fish, squid, copepods, and pteropods (ibid. ).B. Types of Feeding Areas Used
BLcause pink salmon spend such a short time in natal waters
following emergence from the gravel, little data are available on
freshwater feeding locatjons. Samples of pink salmon fry in Lake
Al eknagi k i nd j cat-e that al though they were caught i n the 'lake
I ittoril zone (inshore), their stomach contents indicated that
they had foraged mainly in the pelagic zone of the lake (Rogers
and- Burgner 1967). Juvenile p'ink salmon school in estuarine
waters Jnd frequent the water's edge along mainland and inland
shores (Neave 1966). They remain in nearshore areas for about a
month, and when they have attained a length of 6 to 8 cm they
begin a gradual, irregular movement to offshore waters. 0n the
high seas, pink salmon vertical distribution has been found to
294
V.
range from 10 to 23 n (Takagi et al. .1981), a_'lthough a few have
beei caught at depths fr:on 2[ to 36 m (Neave 1966).
C. Factors Limiting Availability of Food
Because pink saimon feed very little if at all in fresh water, the
major factors f im'iting food- avai'labil ity would be those found in
tha estuarine environhent. Variations in weather patterns and
ocean currents, which affect dispersal of planktonic organ'isms'
could influence food sources for iuveni'le pink salmon.
D. Feeding Behavior
Pink ialmon select the'ir food by sight and swallow it whole
(Bailey 1969). In offshore mapine waters, pink salmon appear to
have a vertical feeding pattern, w'ith light intensity the major
factor. Studies by Shimazaki and M'ishjma (1969) show that feeding
indices of pink salmon near surface waters began to increase
before sunsei, attained a maximum two to three hours after sunset'
and thereafter decreased to a minimum before sunrjse. The feeding
indices again became large in daytime. Whereas the dominant
organisms bf the stomach contents before sunset were large prey
animals such as squids and fjsh larvae' the percentage of amphi-
pods (whose numbers increased in surface waters with darkness), as
ilell as feeding indices, increased after sunset, when amphipods
became the mai-n item of diet. Shimazaki and Mishjma (ibid.)
concluded that darkness prevented pink salmon from seeing and
feeding on amphipods.
REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat
Pihk salmon spawning takes p'lace in a variety of loc-ations. Neave
(1966) states: "In some instances spawning takes place in stream
mouth areas where water levels change with the tides and where
varying degrees of salinity are experienced. In small coastal
str6ami tha upstream 1 jmi i i s usua'l 1y def_i ned by a waterfal I
situated within a few miles of the sea. In larger rivers without
major obstructions, the end-point may be less definite. The
grounds that are intensjvely occupied by pink salmon tend to have
a rel ati vely 'low gradi ent. "B. Reproductive Seasonal ity
In'Alaska, pink salmon ascend freshwater streams from June to late
September, bepending largely on location. Spawn'ing takes_p1ace in
mid July in the lower Yukon but general'ly not until late August to
October in areas to the south (Morrow 1980).C. Reproductive Behavior
As'with other salmon, adult pink salmon return from the sea and
move into their natal freshwater streams to spawn. There is,
however, a degree of wandering. Adults have been taken in
spawning streams as much as 643 km from their origina'l stream.
the femile selects the spawning site and digs the redd (nest) by
turning on her side and thrashing her tail up and down. The
current washes 'l oosened substrate material downstream, and a
depression up to 45.7 cm deep is formed in the river bottom
295
(ibid.). Eggs and sperm (milt) are released simultaneously and
deposited in the redd. After egg deposition, the female moves to
the upstream margin of the redd and repeats the digging process.
Dislodged substrate is washed over the eggs. In this manner the
eggs are covered and prevented from washjng away. The process is
repeated many times, and the redd appears to move upstream (Burner
1951). As a result of the continued digging, the redd may grow to
become 0.9 m in 'length (Morrow 1980). A female may dig severa'l
redds and spawn with more than one male (McPhail and Lindsey
1970). Males may also spawn with several females (Neave 1966).D. Age at Sexual Maturity
Unlike the other Pacific salmon, the pink salmon matures in two
years. Though rare three-year-old fish have been found, it is
probable that they are sterile (Morrow 1980).E. Fecundity
The number of eggs carried by pink salmon entering the spawning
area varies with the size of the female, the area, and the year
(Scott and Crossman 1973). Each female may produce as few as 800
or as many as 2,000 eggs (Morrow 1980), with the average estimatedat 1,500 to 1,900 (Scott and Crossman 1973). In general, larger
fish have more eggs, but fish from small runs are said to be more
fecund than those of the same size from large populations
(Niko'lskii 1952).F. Frequency of Breeding
As w'ith all Pacific salmon, the spawning cyc'le is terminal. Both
male and female die after spawning.G. Incubation Period/Emergence
The amount of time required for eggs to hatch is dependent upon
many interrelated factors, including 1) dissolved oxygen, 2) water
temperature, 3) apparent velocity in gravel, 4) bio'logical oxygen
demand, 5) substrate size (limited by percentage of small fine
material), 6) channel gradient, 7) channel configuration, 8) water
depth, 9) surface water discharge and velocity, 10) permeability,
11) porosity, and 12) light (Reiser and Biornn 1979, Hart 1973).
Generally speaking, factors 4 through L2 influence/regulate the
key factors 1, 2, and 3.
Egb development requires from 61 to about 130 days, depending
laigely on temperature (Morrow 1980). The young hatch from late
December through February and remain in the gravel unti'l April or
May.
VI. MOVEMENTS ASSOCIATED tdlTH LIFE FUNCTIONSA. Size of Use Areas
From studies of Columbia River tributaries, Burner (1951) suggests
that a conservative figure for the number of pairs of salmon that
can satisfactorj'ly utilize a given area of spawning gravel may be
obtained by dividing the area by four times the average size of
the redds. The redd area can be computed by measuring the total
length of the redd (upper edge of pit to lower edge of tailspill)
and the average of several equidistant widths (Reiser and Biornn
296
B.
1979). No documented information on the average size of pink
salmon redds in Alaska waS found in the preparation of this
report.
Timing of Movements and Use of Areas
Pink salmon fry emerge from the gravel at night and begin _their
downstream migiation to the sea (Bajley 1969). During Ju'ly of
!967, small schools of pink salmon fry were observed migrating
upstream along shore through the narrows between Tikchjk Lake and
Nuyakuk Lake in company with larger sockeye. fry and yearlings.
This behavior is unusual for pink salmon (Rogers and Burgner
L967). When the distance to the sea is short, they reac-h the
estuary of the stream before dawn (Ba'i1ey 1969). 0n longer
journeys that cannot be made in one night, the fry hjde in the
grave'l during the day and resume their downstream movement the
next night (Neave 1955). Fry that must migrate for several_days
sometimes become daylight-adapted, in which case they school and
no 'longer hide during the day (Hoar 1956).
After entering the estuary, the iuveniles begin feeding and move
with surface currents (Bailey 1969). After about a month, the
young fish attain a length of 4 cm, then follow the salinity
gnadient within the estuary, generally staying fairly c'lose to the
shore. When they reach a length of 6 to 8 cm they move to
offshore waters (Morrow 1980). After about 18 months at sea, the
adult pink salmon return to fresh water to spawn (Scott and
Crossman 1973).
Migration Routes
Freshwater streams and rivers Serve aS downstream migration
corridors for ocean-bound iuveniles and as upStream migration
pathways for spawning adults.
c.
Fo'llowing is a summary of ocean migration patterns taken from
Takagi et al. (1981). From marine distribution data, it is
evident that pink salmon are present across the entire North
Pacific Ocean from As'ia to North America, north of about 42oN.
Tagging studies have shown that each stock has a characteristic
distribution that is similar in odd-and even-year cycles. When
combined, these studies have shown that the mass of maturing pink
salmon in the North Pacifjc is composed of a number of stocks,
each of which has a rather well-defined distribution that may
overlap with one or more distrjbutions of adiacent stocks.1. Southeastern, Southcentra'|, and Southwestern (south-side of
aska Peninsula) stocks.e oceanic migrations of stocl(s
ing in Southeast, Southcentral, and
Southwest Alaska (south-side Alaska Peninsula) are similar
enough to be treated as one. Genera'l 1y speaki ng ' these
stocks are found in the North Pacific and Gulf of Alaska in
an area bounded on the west by about longititude 165oW, on
the south by'latitude 42'N, and on the east and north by the
North American continent. Juveniles from Southeast A'laska in
their first marine sulnmer and fall move generally northwest-
ward but 'likely do not move far offshore. Juveniles from
297
Southcentral and Southwest Alaska (south of the Alaska
Peninsula) in their first marine sumner and fa'll move south-
westward a'long the Alaska Peninsula. Some iuveniles from
Southeast Alaska may move west and ioin the Southcentra'l and
Southwestern stocks in this area.
Juvenile p'ink salmon are distributed farther offshore in the
north Gul'f of Alaska than they are off Southeast Alaska'
which may indicate that offshore dispersion begins in the
north-ceritral Gulf of Alaska. No adequate measurements of
offshore dispersion have been made south of the Alaska
Peni nsul a .
Assumed migrations during the late fa'll and winter of their
first yeaf at sea indicate that the young pink salmon are
furthei offshore and have begun a general southeastward
movement that probably occurs on a broad front within the
spring-summer distribution. During their second spring anq
summei, the maturing fish begin a general 1y northward
movement from the high seas enroute to their natal streams.
2. Southwestern (north-iide Alaska Peninsu'lqI. Very I ittlenk salmon marine
migrations from stocks in Western and Southwestern A'laska
(n6rth of the Alaska Peninsula). No data are available on
seaward migrations of the juveniles during their first
sunmer. Fr6m small numbers of tag returns of maturing adults
it is supposed that these stocks are found in an area bounded
on the wirst by 180'in the Bering Sea. They mqy also be
found south of the eastern and central Aleutian Islands south
to about latitude 50'N and thence southeasterly to about
'longi tude 140"w at I ati tude 48'N. They probab'ly do not
extend beyond 54'N in the North Pacific.
VII. FACTORS INFLUENCiNG POPULATIONSA. Natural
The greatest natural morta'l i.ty of p'ink salmon occurs duri ng _ the
earl/ I ite stages. Bai'ley (1969) states that, in streams, 'less
than- 25% of the eggs survive from the time of spawning to the time
of emergence f rom
- the gravel ; he I i sts the pri nci p'l.e causes of
death oi the eggs as lJ diggjng in the redds by other females,
Z) low oxygen sufply because bt-low stream flows or impairment of
water cirlilation wittrin the streambed, 3) dislodgement of eggs by
floods,4) freezing of eggs during periods of severe and prolonged
co'ld, and 5) predation by other fish.
Juveniles are'preyed upon Uy a variety of fishes (-e.g., cutthroat
and rainbow troui, Dol'ly Varden, coho salmon smolts, squawfish'
and sculpins), kingfjsher, mergansers, and other predaceous birds
and mammals. Morrow (1980) states that morta'lity during early sea
I ife (first 40 days) is fairly h'igh at 2 to 4% per duy, where
predation by birdi, fishes, and various invertebrates may be an
important fhctor jn mortality at-this time. Adults at sea are
prbyed upon by man, marine mammals, Pacific and arctic lamprey,
298
B.
and to a lesser extent by large fish (Scott and Crossman 1973).
Sea survival rates are highly variable and have been computed at
about 2 to 22% and probably average 5% (Morrow 1980).
Human-rel atedA summary of possible impacts from human-related activities
includes the following:o Alteration of preferred water temperature, pH, dissolved
oxygen , and chemi cal compos i t'ion
" Alteration of preferred water velocjty and deptho Alteration of preferred stream morphologyo Increase in suspended organic or mineral material
" Increase in sedimentation and reduction in permeability of
substrateo Reduction in food supPlYo Reduction in protective cover (e.g., overhanging stream banks
or vegetation)o Shock waves in aquatic environmento Human harvest
(For additional impacts
Water Use volume of this
VI I I. LEGAL STATUSA. Managerial Authority
i nformat'ion , see the Impacts of Land and
seri es . )
The A'laska Department of Fish and Game manages
state and marine waters to the 3-mi limit.
fresh waters of the
The North Pacific Fishery Management Council is composed of 15
members, lL voting and 4 nonvoting members. The 11 are divided as
follows: 5 from Alaska, 3 from Washington, and 3 from state
fishery agenc'ies (A1aska, Washington, 0regon). The four nonvoting
memberi include the director of the Pacific Marine Fisheries
Commission, the director of the U.S. Fish and Wi'ldlife Service'
the commander of the 17th Coast Guard Dj strict ' and a
representative from the U.S. Department of State.
The council prepares fishery management p1ans, which become
federal law and apply to marine areas between the 3-mi limit and
the 200-mi limit. tllith regard to salmon, the only plan prepared
to date is the Salmon Power Troll Fishery Management Plan.
The International North Pacific Fisheries Conmission (INPFC) a
convention comprised of Canada, Japan, and the United States' has
been establ ished to provide for scientific studies and for
coordinating the collection, exchange, and analysis of scientific
data regarding anadromous species.
lrlith regard to salmon, the INPFC has also prepared conservation
measures that limit the location, time, and number of fishing days
that designated high seas areas (beyond the 200-mi limit) may be
fished by Japanese nationals and fishing vessels.
299
IX.
x.
LIMITATIONS OF INFORMATION
Limited life history and habitat information concerning Alaskan pink
salmon has been collected/published. Most of the available information
has been documented from Pacific Northwest and Canadian field'laboratory studi es .
SPECIAL CONSIDERATIONS
Neave (1966) states: "schools of adult pink salmon often frequent bays
and estuaries for days and even weeks before entering the streams.
Fish tagged at this stage still show movements away from, as well as
towards, - tne nearest spawni ng grounds. It appears, therefore, that
spawning populations are not necessarily well segregated until actual
entrance into the spawning streams."
Because of the two-year life cycle, returns of spawning adults are
predictable by highly segregated even-numbered year and odd-numbered
year runs. Both types of runs, or races, may use the same stream, or
ilne or the other -may predominate in a particular river (Scott and
Crossman i973). Some streams with a dominant run of one type have a
very much smaller off-year run of the other race; they often utilize
difierent tributaries as spawning grounds. There may be a significant
difference in the date of return and in the length and weight of
indivjduals of the two races or of the same race in different spawning
rivers ( ibid. ).In addition, caution must be used when extending information from one
stock of pink salmon to another stock. Environmental conditions for
one area must not be treated as absolute; the stocks (races) have
acclimated/evolved over time and space to habitat conditions that can
vary greatly.
The di stri but'i on and abundance narrati ve for the salmon speci es ,
presented by ADF&G commercia1 fisheries management areas, follows the
aggregated salmon life histories.
REFERENCES
ADEC. 1979. Water qual'ity standards. Juneau. 34 pp.
ADF&G, comp. I977a. A fish and wildlife resource inventory o_f the Alaska
Peninsula, Aleutian Islands, and Brjstol Bay areas. Vol. 2: Fisheries.
[Juneau.] 557 pp.
areas.
1977b. A fish and wildlife inventory of the Cook Inlet-Kodiak
Vol. 2: Fisheries. [Juneau.] 443 pp.
. 1978. A fish and wildlife resource inventory of the Prince
-fim
am sound area. vol . 2: Fi sheri es . [Juneau. ] 24r pp.
ADF&G. 1981. Juvenile anadromous fish study on the lower Susitna River.
ADF&G Susitna Hydro Aquatic Studies. Phase 1: Final draft rept.
Anchorage, AK.
300
. 1981a. Lower Cook Inlet annual management report. Div. Cormer.
-Ti-sn.
99 pp.
. 1984. An atlas to the catalog of waters important for spawning'
rearing, and migration of anandromous fishes, Southwestern Resource
Div. Habitat, Anchorage. 5 pp. + maps.Management Region III.
Bai'ley, J.E. 1969. Alaska's fishery resources - the pink salmon. USFWS,
Bureau Cornmer. Fish., Fishery Leaflet No. 619. 8 pp.
Bai'ley, J.E., and D.R. Evans. I97I. The low temperature th-resho'ld for pink
iitmon eggs in relation to a proposed hydroelectric instal'lation.
USFWS, Fish. Bull. 69(3):487-593. Cited in Krueger 1981.
Bailey, J.E., S. Rice, J. Pella, and S. Taylor. 1980. Effects of seeding
densi ty of pi nk salmon, Oncorhynchus gorbyscha ' eggs on water
chemisiry, fry characteristics ant-ffiuriTGT-Tn gravel incubators.
USFWS, Fish. Bull. 78:649-658. Cited in Krueger 1981.
Bell, M.C. 1973. Fjsheries handbook of engineering requirements and
biological criteria. Fisheries Engineering Research Program, Corps of
Engineers, North Pacific Div., Portland, 0R. Approx. 500 pp.
Brett, J.R. 1952, Temperature tolerance in young Pacific salmon, genus
Oncorhynchus. J. Fish. Res. Bd. Can.9(A):ZAS'SZZ.
Burner, C.J. 1951. Characteristics of spawning nests of Columbia River
salmon. USFI^IS, Fish. Bull. 61(52):97-110.
Hart, J.L. 1973. Pacific fishes of Canada. Fish. Res. Bd. Can.
Bull. 180. Ottawa, Can. 739 PP.
Hoar, W.S. 1956. The behavior of migrating pink and chum salmon fry.
J. Fish. Res. Bd. Can. 13(3):309-325. Cited jn Morrow 1980.
Krueger, S.t'l. 1981. Freshwater habitat relationships pink salmon- (0ncorhynchus qorbuscha). ADF&G, Div. Habitat, Resource Assessmentr+Branch. Anchorage. 45 pp.
McPhail, J.D., and C.C. Lindsey. 1970. Freshwater fishes of northwestern
Canada and Alaska. Fish. Res. Bd. Can. Bull. I73, 0ntario, Can.
381 PP.
Middleton, K.R. 1983. Bristol Bay sa'lmon and herring fisheries status report
through L982. Informational Leaflet No. 2II. ADF&G, Div. Cornmer. Fish.
81 pp.
Morrow, J.E. 1980. The freshwater fishes of Alaska. Anchorage, AK: Alaska
Northwest Publishing Company. 248 pp.
301
Neave, F. 1955. Notes on the seaward migration of pink and chum salmonfry.
J. Fish. Res. Bd. Can. 12(3):369-374. Cited in Morrow 1980.
. 1966. Chum salmon in British Columbia. INPFC Bu'11. 18.
Tcouver, Can. 86 pp.
Nikolskii, G.V. 1952. 0 tipe dinauriki stada i kharaktere neresta gorbushi
o.g. (wa]b.): keti o.k. (walb) v Amure. Doklady Adad.-Nauk ussR 86(4).
Ts-raei Prog. Sci. TFansl. 538 pp. Cited in Morrow 1980.
Prokopowich, D. 1983. Personal communication. Kodiak Area Asst. Fisheries
Mgt. Biologist, ADF&G.
Reiser, D.W., and T.C. Bjornn. L979. Influence of forest and rangeland
management on anadromous fish habitat in western North America
habilat requirements of anadromous sa'lmonids. USDA, Forest Service
Gen. Tech. Rept. PNW-6, Pac'ific Northwest Forest and Range Experiment
Station. Portland, 0R. 54 PP.
Rogers, D.E., and R.L. Burgner. 1967. Nushagak district sa'lmon studies.- Pages I2-L4 in J.R. Matches and F.B. Taub, eds. Research in fisheries
- - 1967. Contribution No. 280. College of Fisheries' Fisheries
Research Institute, Univ. Wash., Seattle, WA. 82 pp.
Scott, t^l.B., and E.J. Crossman. 1973. Freshwater fishes of Canada. Fish.
Res. Bd. Can. Bull. 184. 0ttawa, Can. 966 pp.
Shaul, A. 1984. Personal communication. Alaska Peninsula-Aleutian Island
Area Fisheries Mgt. Biolog'ist, ADF&G, Kodiak.
Sheridan, l,l.L, 1962. Relation of stream temperatures to timing of Pi!k
salmon escapements in Southeast Alaska. Pages 87-L02 jn N.J.
l,li'limovsky, ed. H.R. MacMilljan lectures in fisheries: lymposiqm_onpink salmon . 1962. Institute of Fisheries, Univ. Brit. Co'l . ,
Vancouver. 226 pp.
Shimazaki, K., and S. Mishima. 1969. 0n the diurnal change of the feedilS
activity of sockeye salmon in the 0khotsk Sea. Hokkaido Univ., Facul.
Fish., Bul'l . 20(2):82-93. (In Japanese, English summary.) Cited in
Takagi et al. 1981.
Takag'i , K. , K.V. Aro, A.C. Hartt, and M.B. Del I . 1981. Distribution and-origin of pink salmon (0ncorhynchus gorbuscha) in offshore waters of
the North iacific 0cean. --TNFFd;-EuTl .TOlancouver, Can. 195 pp.
Thompson, K. 1972. Determining stream flows for fish life. Pagel 31-50 '!n'Proceedings, instream flow requirement workshop. Pac. Nhl River Basin
Connn. Vancouver, WA.
302
Socheye Salmon Life History and Habitat Requirements
Souttnrest and Southcentral Alasha
Map 1. Range of sockeye salmon (ADF&G .|978, Morrow .|980)
I.
II.
NAMEA. Common names: Sockeye salmon,B. Scientific name: 0ncorhynchus
RANGEA. Wor'l dwi de
red salmon, blueback salmon
nerka
In North America, the sockeye salmon ranges from the
River, Cal ifornia, north to Point Hope, Alaska. In Asia'
salmon are found from northern Hokkaido' Japan' to the
River in northeastern Siberia (Scott and Crossman 1973).
Kl amath
sockeye
Anadyr
B. Statewide
The sockeye salmon is found in stream and river drainages from
Southeast- Alaska to Point Hope, Alaska. Spawning rivers are
usually those with lakes in their systems (Hart 1973).
303
c.Regi ona'l Di stri buti on Summary
To supp'lement the distribution information presented in the text,
a series of blue1ined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale,
but some are at 1:1,000,000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition'
a set of colored 1:1,000,000-scale index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.1. Southwest. In the Kodiak area, major sockeye salmon spawning
ffi-reari ng waters i ncl ude the Karl uk, Red (or Ayakul i k)
River, and Upper Station systems. The Fraser Lake and
Akalura Lake systems are growing in productivity (ADF&G
re77b).In the Bristol Bay area (for waters from Cape Newenham to
Cape Menshikof and north-side Alaska Peninsula systems south
to Cape Sharichef), maior sockeye salmon-producing waters
include the Togiak, Igushik, Snake, Wood, Nushagak, Kvichak,
Alagnak (or Branch), Naknek, Egegik, Ugashik' and Bear river
systems. 0ther important runs are located at Ne1son Lagoon,
Sandy River, Ilnik, and Urilla Bay (ADF&G L977a).
In the waters draining the south side of the A'laska Peninsula
and the Aleutian Islands are found numerous small runs of
sockeye salmon. 0n the south peninsula, Thin Point and
0rzinski lakes are important producers of sockeye salmon
(Shaul, pers. comm.). The most significant Aleutian Island
run is at Kashega on Unalaska Is'land. In the Chignik area,
almost all are found in the Chignik River system (ADF&G
I977a), although there are several other mjnor systems in the
area (Shaul , pers. cornm. ). (For more detailed narrative
information, see volume I of the Alaska Habitat Management
Guide for the Southwest Region.)2. Southcentral. In the Northern and Central districts of Cook
lntFifitmajority of the sockeye salmon are produced in the
Kasilof, Kenai, Susitna, and Crescent rivers and Fish Creek
(Big Lake) systems (ADF&G 1982). In Lower Cook Inlet,
systems producing smaller runs of sockeye salmon are the
English Bay Lakes, Leisure Lake, Amakdedori, and Mikfik
creeks, and Ajalik, Delight, and Desire lakes (ADF&G 1981;
Shroeder, pers. comm.). In the Prince William Sound area,
the Copper River drainage is the maior producer of sockeye,
with runs also found in the Bering, Eshamy, and Coghi'll
systems (ADF&G 1978).
(For more detailed narrative information, see volume 2 of the
Alaska Habitat Guide for the Southcentral Region.)
304
III. PHYSICAL HABITAT REQUIREMENTSA. Aquatic1. Water qual ity:a. Temperature. Egg hatching under experimental conditionsIas occurred across a wjde range of temperatures,
inc'luding 4"C, 15oC, and at descending habitat
temperatures of 13.0 to 5.1"C. The amount of time to
100% hatching in these tests was 140 days,48 days,.and
70 to 82 dayi, respectively (Scott and Crossman 1973).
For iuvenile sockeye salmon the upper lethal temperaturelimit is 24.4"C (Brett 1952), and preferred temperatures
range from 12o to 14'C (ibid.). Smo'lt outmigration fnom
freshwater nursery lakes takes p'lace between 4" to 7"C
(Hart 1973).
Adult spawning has occumed in temperatures ranging from
3" to 10"C (McLean et al. 1977, Scott and Crossman
1973.) Water temperatures of 20oC and more have caused
death i n upstream-mi grati ng adul t sockeye ( Foerster
1e68).
b.Tle p!=faf!of. There is no optimum pH value for fish in
generafi--h-owever, in waters where good fish fauna occur,
lne pH usually ranges between 6.7 and 8.3 (Bell 1973).
State of Alaska water quality criteria for freshwater
growth and propagation of fish call for pH va'lues of not
less than 6.5 or greater than 9.0, with variances of no
more than 0.5 pH unit from natural conditions (ADEC
1e7e ) .
Dissolved oxygen (D.0.). Foerster (1968) cites studies
from the USST indicating that adult spawning has
occurred in lakeshore areas, streams, and spring areas
where the mean D.0. level was 77.47 ng/1 at 3.82'C and
86.13% saturatjon (range of 10.22 to 12.50 ng/1, 3.05 to
4.44"C, and 77.05 to 92.I4%, respective'ly).
State of Alaska water quality criteria for growth and
propagation of fish state that "D.0. shall be greater
than 7 mg/1 in waters used by anadromous and residentfish. Further, in no case shall D.0. be less than 5
mg/l to a depth of 20 cm in the interstitial waters of
grave'l uti I ized by anadromous or resident fish forspawning. . In no case shall D.0. above 17 mg/1 be
permitted. The concentration of total dissolved gas
shall not exceed 110 percent of saturation at any point
of sample colIection."Turbidity. Sed'imentation causes high mortality to eggs
anil-T1 wl n by reduci ng water i nterchange i n the redd.If 15 to 20% of the intragravel spaces become filled
with sediment, salmonoid eggs have suffered significant
(upwards of B5"I) mortal ity (Bel I 1973). Prolonged
exposure to turbid water causes gi'11 irritation injuveniles, which can result in fungal and pathogenic
c.
d.
305
B.
bacterial infection. Excess turbidity from organic
materials in the process of oxidation may reduce oxygen
below safe levels, and sedimentation may smother food
organi sms and reduce primary producti vi ty ( i bi d. ) .
ruiutd water wi'll absorb more solar radiation than c'lear
water and may thus indirectly rajse thermal barriers to
migration (Reiser and Biornn 1979).
2. Water quantity:
a. Instrean flow. Sufficjent water velocity ("flow," in
ffi rivers and streams; and "springs" or
seepage, in the case of lake spawning) and depth -areneeded to allow proper intragravel water movement. This
flow is required to provide oxygen to the developing
eggs and alevjns and to carry away metabo'lic waste
pi6Oucts (Reiser and Bjornn 1979, Foerster 1968).
iJpon emergence from the grave'l , the juveniles must have
sirfticieni water available to be able to move to their
nursery lake.
Excessive velocities may impede upstream migrating
adults. Experiments in Canada discussed by Foerster
( 1968) concl uded that none of the 406 mature sockeye
salmon tested could withstand a current of 2.86 m/s for
two minutes, and 50% could not maintain pos'ition for 65
seconds. Reiser and Biornn (1979) suggest that 2.I3
m/sec is the maximum velocity that sockeye salmon can
successful'ly negotiate during their spawning runs. They
also suggest that optimal ve'locity at spawning sites
ranges from .2I to 1.01 m/sec and that depth of water is
usuilly .15 m or less. No information for adult sockeye
salmon migration or spawning criteria in Alaska were
found during the literature review.
3. Substrate. Egg incubation and development occur in substrate
ranglng widely-in size and composition. Morrou (1980) states
thal spawning nests are usual'ly constructed where the bottom
is finb grav-e1 but that they may be over large pebbles- of 5
to 10 cn in diameter or even over 'large rocks. Preferred
sites have less than 10% of the gravel larger than 7.5 cm in
diameter, about 50% of the gravel between 2.5 and 7.5 cm in
diameter, and the remaining gravel smaller than 2.5 cm in
di ameter ( i bi d. ) .
Terrestri al1. Conditions provjdinq security from predators or other dis-
T2. eondlTi-ons prov'idinq protection from natural elements.
surface
ice and sunlight.
306
IV. NUTRITIONAL REQUIREMENTSA. Food Species Used
Upon hatching, young alevin remain in the gravel for several weeks
until the yolk sac is absorbed. After emerging from the grave'|,
they usua'l1y swim to a lake to begin feeding. Juveniles' during
their first few weeks in the nursery lake, feed'largely on
ostracods, cladocerans (water fleas), insects, and insect larvae
(Morrow 1980, Hart 7973, Foerster 1968). After moving to deeper
water, the young sockeye salmon become pelagic and feed on
plankton in the upper 20 m or so. The maior summer food items are
copepods (Morrow 1980).
While in salt water, young sockeye salmon near shore eat insects,
small crustaceans or zooplanktons (e.g., copepods, amphipods'
decapods, barnacle larvae, ostracods, and euphausiids), and such
young fishes and larvae as sand lance, bigeye whiting, rockfishes,
bulaihon, starry flounder, herring, prickle backs, and hake (Hart
1e73).
0n the high seas, the grow'ing fish consume ever larger pr€J, which
includes such crustaceans as euphausiids, amphipods, and copepods
and also includes squ'ids and young fishes (ibid.).
B. Types of Feeding Areas Used
When they first enter the nursery 1ake, sockeye salmon juveniles
feed along the shore for a few weeks but soon move out over the
deeper water in the body of the lake, where they are concentrated
in the top 1.0 or 20 m but may be found as deep as 40 m or more(ibid.). In the Wood River system, Bristol Bay area, Alaska,
Burgner (1958) reports that "while the fry do leave the rivers
between lakes soon after emergence, downstream migration of fry in
most of the tributary creeks is not comp'leted for some time after
breakup of the lake ice. In many creeks a portion of the fry
population remains to feed and sometimes the fry acquire
considerable growth before entering the lake. Sockeye fry jn the
Wood River lakes are observed in abundance a'long the lake shores
for at least a month after breakup of the lake ice. l^lhen the'lake
level js high ear'ly'in the season they are to be found in droves
in flooded grass a'long protected areas of the lake shore."
After migrating to salt water, the young sockeye salmon at first
stay fairly c]ose to shore (within 50 km) (Morrow 1980, Hart 1973,
French et al. I976), although they are not seen regularly near
shore for several weeks during the summer as young pink salmon and
chum salmon are (Ricker 1966).
As the young sockeye salmon get bigger and stronger, they head out
to sea. Vertical distribution studies discussed by French et al.
(1976) show that sockeye salmon occupy depths to at least 61 m and
may go deeper; most catches (90%), however, were within 15 m of
the surface. These studies also suggest that the thermocline may
ljmit the depth to which sockeye salmon descend.
Morrow (1980) states that the anea bounded on the north by the
Aleutians, on the south by 50'north latitude, on the west by 165
to 170o east longitude, and on the east by 160'west longitude is
307
V.
an important late spring, summer, and autumn feeding area. By
late winter the sockeye ia'lmon have left this area and are found
in a broad band across the north Pacific south of 50oN.
C. Factors Limiting Availability of Food
The well-being ind growth of-young sockeye sa'lmon {epe.nd primarily
on 1) the abu-ndance of the food organisms on whi.ch they subsist'
2) the numbers of young sockeye present, and 3) the numbers of
oiher species of filh in the iake that compete "i!f, sockeye for
food (Foerster 1968). Further, temperature conditions ' water
transparency, and chemical condjtions (particularly the amounts of
nitrates, nitrites, phosphates, and silicates) all have a direct
jnfluence on the productfon of plankton populations, which are the
main food of the Young fish (ibid.)
D. Feedi ng Behav'ior
JuveniTes in nursery lakes feed in schools (Hartman 1971).
Maturing sockeye salmon stop feeding as _they ne-ar fre.sh water, and
the spa-wni ng ii str deri ve nouri shment from o.i I s and prote'i ns of
thej r 'fl esh ,- skel etal structures , and scal es ( i bi d. ) .
REPRODUCTIVE CHARACTERISTI CS
A. Reproductive Habitat
Sphwning occurs primarily in streams that connect with lakes
(i',lorrow- '1980) , al though some popul at j ons spay!_ al ong_. l ake shore
beaches and iitana beiches in'likes (Morrow .|960, McPhail 1966)'
and other populations spawn in streams with slow-moving reaches
but no lakes'in the system (Morrow .|980; Roberson' pers. corrn.).
Factors determining the selection of spawning sites are varjable
and include stream grad'ient, water depth.and velocity, and the
size of the streambed materials (substrate). Spawn'ing sites are
usually selected where there is a good. waterflow througtt !h.
grave'l- (ADF&G 1977). These areas may be 1) jn the streams f'lowing
into thd lake,2) in the upper secti-ons of the outlet river, qf 3)
alonq the shores'of the lake where "Springs" or seepage outflows
occui (Foerster 1968).
In sumrnarizing Alaslian spawning waters, Foerster (1968) states:
". a reviiw of ava'ilable evjdence indicates that in general,
while stream spawn'ing is still the most important, lake-beach
spawning increases jn extent and s'ignificance (when compared to
Cinadiai waters). At Karluk Lake on Kodiak Island, jt is reported
that about 75 percent of the spawning occurs jn the streams, the
remaining 25 percent on the lake beaches. For Bristol Bay and its
highly p-roAuitive sockeye salmon areas there appears to be a
trinsiti'on in importance-of specific types of spawning ground. In
the eastern part, stream spawning ranks as the most important.
The Naknek anb Kvichak Riven systems each have a number of smaller
lakes auxiliary to the main lake. Salmon spawn in streams
tributary to thlse lakes as well as in streams connecting-them to
the main'tate. .the spawning in both systems'is confined to
stream bed areas rather ttran beaches. Further west, however, in
the Nushagak River system which comprises 10 major lakes, the
308
B.
sockeye spawn principally in the rivers between lakes and along
lake shore beaches, although there are also a few important
tributary streams."
During .|965, a study of Iliamna Lake revealed that island beaches
used for spawning showed no evidence of upwel 1 ing water;
apparently the eggs are washed by means of wind-caused lake
currents (McPhail .|966).
Reproductive Seasonal ity
In Alaska, adult sockeye salmon ascend their natal streams from
early May to October, dependjng on the geograph'ic location (Morrow
1980; ADF&G 1977; Roberson, pers. cornn.). Region-specific run
t'iming and spawning time informatjon is presented in the Salmon
Distribution and Abundance narratives prepared for each of the
regions addressed in this series of pub'lications.
In-general, fish breeding in lakes and their outlet streams spawn
later than those spawning in streams (ADF&G 1977). _This breeding
characteristic, however,-js by no means universal (Morrow '1980).
Roberson (pers. comm. ) notes that several factors affect the
periods that have evolved to become the spawning times of
different populations of sockeye sa1mon. Among these factors are
the average water temperatures during egg incubation and alevin
development, the feeding potentia'l upon emergence from the gravel'
and water temperature and velocity during adult migrat'ion.
A few exceptions to the general spawning time characteristics
mentioned above are found in Upper Mendeltna Creek (outlet stream
of 0ld Man Lake), where spawning occurs early and spawners are
dead by June 30; in Dickey Lake (at the headwaters of the Middle
Fork of the Gul kana R'i ver) , where spawni ng occurs early and
spawners are dead by July 30; and in the Gulkana River Springs'
where Spawning occurs late and spawners are dead by'late November
(iUiO.1. Likewise, the general t'iming characteristics do not hold
true for Bear Lake on the north side of the A]aska Peninsula or
for Chignik Lake on the south side of the Alaska Peninsula (Shaul'
pers. comm. ) .
Reproducti ve Behav'i or
As with other salmon, adult sockeye return from the sea and move
into their natal freshwater Streams or lakes to spawn. The female
selects the spawning site and digs the redd (nest) by turning on
her side and thrashjng her tail up and down. The current washes
loosened substrate material downstream, and a depression 35 to 41
cm deep is formed in the river bottom (Hartman 1971, Morrow 1980).
Eggs and sperm (milt) are released simultaneous'ly and deposited in
the redd. After egg deposition, the fema'le moves to the upstream
margin of the redd- and repeats the digging process. Dislodged
substrate is washed over the eggs. In this manner, the eggs are
covered and prevented from washing away. The process. is repeated
several times, and the redd appears to move upstream (Burner 1951,
Morrow 1980). As a result of the continued digging, the redd may
grow to become 1.0 to 7.0 m2, depending on the concentration of
iistr in the area, although under "normal" conditions a size of 1.6
c.
309
m2 to 2.9 s2 is more like'ly (Foerster 1968). The ADF&G (1977)
states that the redds of I ake spawners are usua'l 1y 'larger than
L.75 sz and are more irregular in shape than redds of stream
spawners. A female may dig several redds and spawn with more than
one male. Ma'les may- also spawn with several females (Morrow
1e80).D. Age at Sexual Maturity
Morrow (tSeO1 states: "Most sockeye salmon from British Columbia,
Canada, spend one year in fresh water and two in the sea 'returning to spawn in their fourth year. Farther north, however'
two years in fresh water and two or three in the sea are common.
Therefore many Alaskan sockeye return in their fifth or sixth
years. "E. Fecundity
The number of eggs produced by ind'ividual females varies with the
stock, posit'ive'[y with the size of the fish and with the ear]ier
migrat'ion history of the individual fish,. shorter saltwater life
being associated with h'igher egg counts (Hart 1973). The female
usually produces 2,500 to 4,300 eggs (Morrow 1980).
F. Frequency of Breeding
As with all salmon, the spawning cyc'le is termina'l . Both male and
female die after sPawning.G. Incubation Period/Emergence
The amount of time requ'ired for eggs to hatch is dependent upon
many interrelated factors, including l) dissolved oxygen, 2) water
temperature, 3) apparent velocity in gravel, 4) biological oxygen
demand,5) substrate size ('limited by percentage of sma'll fine
material), 6) channel gradient and 7) configuration, 8) water
depth, 9) surface water-discharge and velocity, 10) permabi'l ity,
11) porosity, and 12) light (Reiser and Biornn L979, Foerster
1968) . Genera'l 1y speaki ng, factors 4 through L2
influence/regulate the key factors 1, 2, and 3.
Development of eggs takes six to nine weeks in most areas bu_t may
requi re as l ong as f i ve months , the time dependi ng 'large'ly 9lwater temperature (Hart 1973). Hatching usual'ly occurs from mid
winter to' early spring, and the alevins emerge from the gravel
from April to June (Morrow 1980).
VI. MOVEMENTS ASSOCIATED h|ITH LIFE FUNCTIONSA. Size of Use Areas
From studies of Columbia River tributaries, Burner (1951) suggests
that a conservative figure for the number of pairs of salmon that
can satisfactori'ly utilize a given area of spawning gravel may be
obtained by divid'ing the area by four times the average size of
the redds. Redd area can be computed by measuring the total
length of the redd (upper edge of p'it to lower edge of tailspi'!1)
and-the average of several equidistant widths (Reiser and Bjornn
1979). Information obtained by Mathisen (cited in Foerster 1968)
from observations in Pick Creek, Wood River system, Bristol Bay
area, Alaska, shows that under compet'itive conditions for space
310
B.
each female usual 1y manages to average 3.7 s2 as spawning
territory. lrlhen competition for space is eliminated each female
occupies an average area of 6.97 n2. The ADF&G (1977) states that
a rebd (presumably in Alaska) generally averages 1.75 n2 in stream
spawning'areas. No specific data on redd size in Alaskan
lake-spawning areas was found during literature review.
Timing of Movements and Use of Areas
In Aliska, alevins emerge from the grave'l during the period April
to June (Morrow 1980) and are light-sensitive, tending to hide in
the stones and gravel of the stream bottom by day and coming out
at night. In a few populations, the fry go to sea during their
first summer, but thA vast maiority spend one or two years (in
rare cases three or four years) in a lake ( ibid.). After the
juveniles emerge from the gravel in lake tributaries, those_in
inlet streams go downstream to the lake, and those in outlet
streams swim upstream to the lake. They migrate singly at night
and thus minimize the dangers of predation (Hartman 1971,). 0nce
in the lake the juveni'les move about in schools and stay close to
shore for the first few weeks before moving to deeper water. In
over 30 Streams of the Copper River dra'inage' young sockeye salmon
stay in the stream and move to slow-moving. sections of the river
beciuse no lake is available in the system-(Roberson' pers. conun.)
After a year in the lake, often two ye.ars and sometimes three
years ii many Bristol Bay areas (Bucher' pers. comm. ) ,
imoltification occurs (the young fish lose their parr marks and
turn si'lvery), and they migrate downstream. Most of the_migrants
move at night (Morrow 1980), the migration apparent'ly- being
triggered when the nursery lake's temperature approaches 4oC. The
peak of the Bristol Bay outmigration occurs during June.
Following is a summary of ocean chronolog'ica1 distribution as
stated by French et al. (tgZ6):
After entering the open ocean in the late spring or early summer
the young fish (age .0) genera'l1y are found a'long the coastl jnes
within about 50 km of shore but tagging has shown that many of
them migrate hundreds of kilometers within this coastal belt. The
timing and locations of their offshore migrations are unknown. In
the winter as age 0.1 fish they appear to be distributed broadly
across the North Pacjfic Qcean and Bering Sea. The greatest
abundance occurred between 50oN and 45oN. By spring the young age
0.1 fish have reached their southernmost limit of migration which
in May is about 44"N in western and central North Pacific waters
and somewhat north of this latitude in the northeastern Pacific.
June finds the age 0.1 fish moving northward, a migrat'ion that
continues until August. During the summer the sockeye extend-in a
continuous band acioss the North Pacific Ocean from near 140'W to
160"E and general'ly between 50"N and 53"N; their movement is pro-
nouncedly westward as they approach the Aleutian Islands from the
south and east. The fish are also found in abundance in the
central and western Bering Sea, from 175'W to 165'E from the
Aleutian Islands to near 61"N.
311
Little is known of the distribution of the age 0.1 sockeye salmon
in fall other than that migration must be southward for the fish
to atta'in their winter distribution. The winter distribution of
the now age 0.2 fish is generally similar to that which they had
as age 0.1 immatures, although they stay 2" or 3o north of their
former range. In winter the center of concentration is general'ly
north of 49"N in the northeastern Pacific Ocean, east of 165oW,
and may extend somewhat farther south in the central and western
North Pacific. The fish in winter extend across the North Pacific
from near 140'W to about 165'E. In spring they commence their
inshore spawning migrations and have essential'ly left the high
seas by the end of Ju1y.
Sockeye salmon that remain in salt water for an additiona'l season
(age 0.3 fish) winter in areas somewhat north of their age 0.2
range.
Both age 0.2 and age 0.3 groups occur in the Bering Sea in winter
(the age 0.3 fish apparently in greater abundance than the age 0.2
f i sh ) . The di stri buti on and mi grat'ion of these stocks unti'l they
leave for the spawning grounds is not known. It is known, how-
ever, that they are not found in abundance over the continenta'l
shelf areas of the eastern Bering Sea except during migration to
and from spawning streams but remain in deep water parts of the
ocean in the central and western Bering Sea (French et al. 1976).
C. Migration Routes
Freshwater I akes, streams, and rivers serve as corridors for
downstream migration of ocean-bound iuvenile sockeye salmon and
upstream migration of spawning adults. The fo'l'lowing ocean
migration routes are taken from French et al. (1976).
t,lhile in the ocean, juvenile (age 0.0) sockeye salmon from western
A'laska (primarily from streams that are tributary to Bristol Bay)
move southwest a'long the north side of the Alaska Peninsula, then
southwestward a'long the Aleutian Is'lands, and then south through
various passes (most like1y east of 175"E) into the North Pacific
Ocean. By January 1 of their first year at sea' the now age .1
sockeye salmon have moved south of the Alaskan Stream and Ridge
Area to areas primari 1y south of 50oN in Western Subarctic
Intrusion or Transition Area waters. By Apri1, the fish have
reached their southern limit from 45'N to 50oN. In June, the
sockeye begin a northward movement and by July are found north of
50oN in the Alaska Stream and Ridge Areas, with a broad east to
west distribution from about 170'E to about 150't^l. There is a
pronounced westerly migration during the summer, particu'la11y
close to the south side of the Aleutian Islands. Some e'lements of
the population move northwestward into the centra'l and western
Bering Sea in summer and are found to at least 60oN and to 166oE.
The circuit is general 1y repeated again with a few minor
variations as the stocks separate jnto mature and immature stages.
Suffice it to say that maturing fish tend to stay a bit (2'-3')
north of their first year's southern limit. In June, the spawning
3t2
migration toward Bristol Bay occurs over a broad front from about
166'E to near 140'W.
Sockeye salmon stocks from the Alaska Peninsula (south-side
streams), Southcentral, and Southeast Alaska generally mix during
their reiidence in the northeastern Pacific 0cean. Depending on
orig'in, they move northward, westward, or southward in a_general
countei-cloikwise pattern along the coast as age .0 iuveniles. By
January, the age .1 fish have moved generally west and south into
feedi n-g
- groundi we1 I offshore. In the spri ng (June ) , a norther'ly
movement'begins, and by July they are widely spread-throughout the
northeasteri Pacific Otean.- By late summer, migration is westward
and southwestward until their-distribution lies probab'ly west of
145"W and north of 49"N (some may go as far west as L77"E during
their second summer at sea). tn tne fal1, the fish turn southward
and eastward and by mid winter occupy an area from near 140oW to
165'W. There is iome separation of age groups of fish at th'is
time: the maturing fish age .2, the ones that will spa$,n the next
season, tend to be in more northern areas of the winter range_.in
the noitheastern Pacific 0cean. In the spring, the maturing fish
migrate northerly, easterly, and westerly. from an afqa generally
eait of 160'W ani north of 46"N towards their respective spawning
streams. The circuit is repeated for those sockeye that remain in
the marine environment for three and, rarely, four years.
VII. FACTORS INFLUENCING POPULATIONSA. Natural
Deposition of silt in the redd, reduc'i.ng water f1_0.w, may res_ult in
heivy mortality of eggs and alevins (Morrow 1980). Juveni'les in
theii nursery lakes must compete for food with other species and
are preyed upon by Do11y Varden, char, squaw_f-ish, rainbow trout'
coho' silmon, and prick-'ly sculpin (Hart 1973). Adults may _bepieyed on bi Paciiic ha-rbor seals
.
(Phoc.a vilulina richa,rds j),
bears, sea gu1ls, and man (Foerster 1968). An increase in the
abundance of-predatory marine fishes may also be a very big factor
(Shaul, pers. comm. ).B. Human-relatedA summary of possible impacts from human-related activities
includes the following:o Alteration of preferred water temperatures, pH, djsso'lved
oxygen, and chemical comPosition
' Allaration of preferred water velocity and deptho Alteration of preferred stream morphology
" Increase in suspended organic or mineral materialo Increase in sedimentation and reduction in permeability of
substrateo Reduction in food suPPlYo Reduction in protective cover (e.9., overhanging stream banks
or vegetation)o Shock waves in aquatic environmento Human harvest
313
I
A. Managerial AuthoritY
The Alaska Department of Fish and Game manages the fresh waters of
the state and marine waters to the 3-mi limit.
The North Pacific Fishery Management Council is composed of 15
members, ll voting and 4 nonvoting members. The 11 are divided as
follows: 5 from Alaska, 3 from Washington, 3 from state fishery
agencies (A1aska, Washington, 0regon). The four nonvoting members
iiclude the director of the Pacific Marine Fisheries Cormissjon,
the director of the U.S. Fish and t.lildlife Service, the corrnander
of the 17th Coast Guard District, and a representative from the
U.S. Department of State. The council prepares fishery management
p1ans, which become federal 'law and apply.to marine areas between
the g-m'i I jmit and the 200-mi 'limit. t,'tith regard to salmon, the
only pl an prepared to date 'is the Salmon Power Trol 'l F'ishery
Management Plan.
The Internatjonal North Pacific Fisheries Commission (INPFC), a
convention comprised of Canada, Japan, and the United States, has
been establ jshed to provide for scientific studies and for
coordinating the collection, exchange, and ana'lysjs of scjentific
data regard'ing anadromous species.
14jth re-gard to salmon, the INPFC has also prepared_ conservation
measu.ei that limit the location, time, and number of fishing days
that desjgnated high seas (beyond the 200-mi lim'it) areas may be
fished by Japanese nationals and fishing vessels.
IX. LIMITATIONS OF INFORMATION
The physical habitat requirements for sockeye salmon are less well
docuniented than other aspects (timtng and movement patterns, e.9.,) of
this spec'ies' freshwater residency in Alaska.
X. SPECIAL CONSIDERATIONS
A freshwater form of this species exists and is known as the kokanee.
The kokanee is genera'l1y very simjlar to the anadromous sockeye salmon
except that it is smaller in ultimate 'length
_and wejght and spends its
entii^e life in fresh water. It, too, dies after spawning.
In addition, cautjon must be used when extending information from one
stock of soikeye salmon to another stock. Environmental conditions for
one area musf not be treated as abso'lute; the stocks (races) have
icclimated/evolved over time and space to habitat conditions that can
vary greatly.
(for additjonal imPacts
Water Use volume of this
VIII. LEGAL STATUS
information see the Impacts of Land and
seri es . )
314
REFERENCES
ADEC. 1979. Water quality standards. Juneau. 34 pp.
ADF&G, comp. L977. A compilation of fish and wildlife resource information
for the State of Al'aska. Vol. 3: Commercial fisheries. [Juneau.]
606 pp.
. 1977a. A fish and wildlife resource inventory
---PE-ninsula, Aleutian Islands, and Bristol Bay area. Vol'
[Juneau. ] 557 PP.
1977b. A fjsh and wildlife inventory of the Cook Inlet-Kodjak
Vol. 2: Fisheries. fJuneau.] 443 pp.
. 1978. A fish and wjldljfe resource inventory of the Prince
-TTI-Iiam
Sound area. Vol . 2: Fisheries. [Juneau.] 24I pp.
ADF&G. 1981. Lower Cook Inlet annual management report. Div. Conrner.
Fish. 97 pp.
. I1BZ. Stock separation feasibility report. Phase I: Final draft.
--TD-rAG, Susitna Hydro Adult Anadromous Fish Proj. 75 pp.
Bell, M.C. Lg73. Fisheries handbook of engineering. lequirements and
biological criteria. Fisheries-Engineering Research Prog. Corps. of
Engin6ers, N. Pac. Div., Portland, 0R. Approx. 500 pp.
Brett, J.R. L952. Temperature tolerance in. youlng _Pacific salmon' genus
0ncorhynchus. J. Fish. Res. Bd. Can. 9(6):265'3?2.
Bucher, W.A. 1984. Personal communication. ADF&G, Asst. {rea Fisheries
Biologist for west-side Bristol Bay, Div. Commer. Fish., Dillingham.
Burgner, R.L. 1958. A study of the fluctuatjons in abundance, growth, and" suivival in the early iife stages of red salmon (0frcorhyndrus nerka,
W;ib.ilj of the Wood Rjver lakei, Bristo'l Bay, Alaffi-Ftl. TIET|S,
univ. washington, Seattle. 200 pp. cited in Forester 1968.
Burner, C.J. 1951. Characteristics of spawning nests of Columbia River
salmon. USFt,lS Fish. Bull. 61(52):97-110.
Foerster, R.E. 1968. The sockeye salmon, 0ncorhynchus nerka. Fish. Res.
Bd. Can. Bull. 162, 0ttawa, Can. 422 pp.
French, R., H. Bilton, M. Osako, and A. Hartt. 1976. Distributjon and- oilgin of sockeye salmon (Oncorhynchus nerka) in offshore waters of the
t',tor[h Pacific 0lean. INPFBuTT--34. IETc-ouver, Can.
Hart, J.L. t973. Pacific fishes of Canada. Fish. Res. Bd. Can. Bull. 180.
0ttawa, Can. 739 PP.
of the Alaska2: Fisheries.
areas .
31s
Hartman, 14.L. 1971. Alaska's fishery resources the sockeye salmon. N0AA'
NMFS, Fishery Leaflet No. 636. Seattle, WA. 8 pp.
McPhail, J.D., ed. .|966. Studies of sa'lmon in fresh water in
Aliska-Kvichak sockeye. Pages 9-11 in Research in fisheries-I965.
Contribution No. 2i2. College of -Fisheries, Fisheries Research
Institute, Univ. Wash., Seattle. 40 pp.
Morrow, J.E. 1980. The freshwater fishes of Alaska.
A1 aska Northwest Publ ishing Company. 248 pp.
Anchorage, AK:
Reiser, D.W., and T.C. Biornn. 1079. Influence of forest and rangeland
minagement on anadromous fish habitat in Western North America
habiiat requirements of anadromous salmonids. USDA Forest Serv. Genl.
Tech. Rept. PNW-6, Pacific Northwest Forest and Range Experiment
Station. Portland, 0R. 54 PP.
Ricker, W.E. 1966. Salmon of the North Pacific Ocean. Part III: A review
oi the life history of the North Pacific salmon. INPFC Bull. 18.
Vancouver, Can.
Roberson, K. '1985. Personal cornmunication. Research Project Leader'
ADF&G, Div. Commer. Fish., Glennallen.
Schroeder, T. .l985. Personal communication.
ADF&G, Div. Commer. Fish., Homer.
LCI Anea Mgt. Biologist,
Scott, }r|.8., and E.J. Crossman. 1973. Freshwater fishes of Canada.
Fi sh . Res . Bd. Can. Bul 'l . 184. Ottawa , Can. 966 pp.
Shaul, A. 1984. Personal comnunication. ADF&G, Alaska Peninsula-Aleutian
is'land Area Fjsheries Mgt. Biologist, Kodiak, AK.
316
Marine Fish
Pacific Cod Life History and Habitat Requirements
Soutlrwest and Southcentral Alasha
t40 tcoE tlo lcolv 140
Map 1. Range of Pacific cod (Sa'lverson and Dunn 1976)
I.NAMEA. Common Name: Pacific codB. Scientific Name: Gadul macrocephalus (Tilesius)
I I. RANGEA. Worldwide
Pacific cod are found from Santa Monica Bay, California, around
the North Pacific rim to the northern part of the Yellow Sea.
They are also found in the Bering Sea (Salveson and Dunn 1976).B. Regional Distribution Surrnary
To supplement the distribution information presented in the text,
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 _scale,but some are at 1:1,000,000 scale. These maps are available for
319
r
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addjtion,
a set of colored l.:1,000,000-scale index maps of selected fish and
wi'ldlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.
1. Southwest. In the Gulf of Alaska, cod are most abundant in
Tfi'6=JEGrn (Kodiak and Alaska Peninsula) regions (Reeves
1972, Hughes L974, Ronhol t et al. L977). Traw'l sulveys.
conducted- in the Gulf of Alaska from 1973 through 1976 found
hiqhest cod CPUE in the Kodiak and Sanak regions (Ronholt et
all Ig77). In the Bering Sea the most productive fishing
areas for cod are in the- outer shelf, northwest of Unimak
Island (Jewett L977, Low 1974). (For mfore detailed
narrative information, see vo1ume 1 of the Alaska Habitat
Management Guide for the Southwest Region.)
2. Southcentral. Cod are distributed throughout the Southcen-
ffin. Trawl surveys conducted in the Gulf of Alaska
from 1973 through I976 found the h'ighest cod catch.per unit
effort (CPUE) in Southcentral to be in the Kenai (south of
the Kenai Peninsula) area (37,7 kg/hr) (Ronho'lt et al. L977).
(For more detailed narrative information, see volume 2 of the
Alaska Habitat Management Guide for the Southcentral Region.)
III. PHYSICAL HABITAT REQUIREMENTSA. Water Depth
Pacific'cod are mostly benth'ic and are found at depths ranging
from 15 to 550 m (Mo'iseev 1953). Research vessel surveys carried
out in the Gulf of Alaska from summer 1980 to late winter 198?
found that the highest Pacific cod density was in the 51 to 100 m
depth interval (Zenger and Cummings 1982). Their depth distribu-
tibn varies, howevei, with the location of the stock and the time
of year.B. Water Temperature
Water temperature is very important to the hatching success and
survival of cod eggs and may in that way determine the lim'its of
Pacific cod distribution -(Alderdice and Forrester l97L). In'laboratory experiments, Alderdice and Forrester (1971) found that
temperatures of 3.5 through 4.0oC were optimal for egg development
and that 50% or greater survival could be expected in a tempera-
ture range from 2.5 to 8.5oC. Survival drops off more rapidly in
temperatures below optimum than in temperature-s _above optimum.
Yamamoto and Nishjoka (tgSZ) found that optimal larval survival
was at 7 to BoC.C. Water Chem'i stry
Eggs are tolerant of a wide range of oxygen and salinity.levels.
Ii- temperatures are wi thi n the optimum range, €9_9S- to1erate
di ssol v'ed oxygen I evel s f rom satur4tion down to 2-3 ppm and
salinities from at least 12.71 to 23"/00 (Alderdice and Forrester
1971 ) .
320
IV. NUTRITIONAL REQUIREMENTSA. Food Species Used
Studie! from the southeastern and Kodiak areas of the Gulf of
Alaska found that fish, crabs, and shrimp were the maior foods of
adult cod in those aieas (Jewett 1978, Clausen 1981). In the
Kodiak area, the fish most frequent'ly found in cod stomachs was
wa'l 1 eye poil ock (Theragr,a cha'lc.ogramTa ) . . Fl atf i shes (P'leuro-
necti-dae)' and PacjiTilaiFtance TAinmoAfies hexlpterus) -were al so
commonly found (Jewett 1978). In the southeastern gulf' Pacific
herring- (clupea hargngus pallasi) and .wall.eye po1'l.ock.wqre..Fut9!
V.
most often. In EoTfi--rcafiE-nner crab (Chionoecetes bgirdi) was
itre most commonly consumed crab. Clausen'lI96ITT6-fEd ffit cod in
outside waters ate a larger volume of crabs than those in inside
waters and, conversely, that cod in jnside waters ate a higher
volume of shrimp (eipecial ly pandal id shrimp) and more fish
(especially Pacific herring) than cod in outside waters.
in'the Bei'ing Sea, a 1980 Northwest and Alaska Fisheries Center
(NhlAFC) study reported that pollock, shrimp, other invertebrates'
ind Tinner -cra6 were most frequently found in cod stomachs
(Bakkala 1981). Some variation in food habitat by regjon was also
noted. In Bristol Bay, the principal food jtem was Tanner crab;
i n the central Beri ng sea , pol 1 ock , Tanner crab , and other
invertebrates; and in ihe northern Bering Sea, shrimp and pollock
(ibid.).
iorng-ioa teea on copepods and similar organisms (Morrow 1980).
B. Types of Feeding Areas Used
Noiseev (1953) ieported that in the western Bering Sea and the Sea
of 0khotsk cod niigrate to shallow waters in search of food in
early spring. Cod in other areas also follow short seasonal
migrltory palterns, spawning in relatively deep water and moving
to more-shallow water while feeding in the spring (Jewett 1978,
Forrester 1969, Ketchen 1961).C. Factors Limiting Availability of Food
No information -is available concerning limitations of cod food
supply.D. Feeding Behavior
Pacifii cod do not feed during spawning (Moiseev 1953). They are
apparent'ly somewhat opportuni stic feeders; the abundance of
preferred prey items in their stomachs varies with the abundance
of those piey-items in the environment (Clausen 19Bl).
REPRODUCTIVE CHARACTERISTI CSA. Reproductive Habitat
Cob generally migrate to re'lative'ly deep water (80 to 290 m) to
spawn (Ketchen 1961, Mojseev 1953). An exception to this is in
the southern part of their Asian range, where the cod move inshore
to spawn in waters 15 to 50 m deep (ibid.). Location of spawning
is probably more closely corre'lated to water temperature than to
Aepifr (see the discussion of egg survival under section III.)
(Aiderdice and Forrester 1971).
32r
Spawning is probably inhibited at temperatures above 9oC or below
o"c (ibid. ).
Spawning usually occurs in the western Bering Sea at depths of 100
to 250 m and at temperatures of 0 to 3"C (Musienko 1970).B. Reproductive Seasonal ity
Spawning takes place during the winter months. In Canadian
coastal waters, spawning takes place from January to March
(Ketchen 1961). In the eastern Bering Sea, spawning probably
takes place from January to April (Bakkala 1981).C. Reproductive Behavior
No information is available on Pacific cod breeding behavior.D. Age at Sexual Maturityln gritish Columbia waters, male cod mature at age two (49 cm in
length). At age three (55 cm)r 50% of female cod are mature
(Forrester 1969). Teshima (1983) stated that female Pacific cod
in the eastern Bering Sea apparently reach maturity at a length
greater than 65 cm.E. Frequency of Breeding
Cod breed annual 1y.F. Fecundity
Fecundity increases with the size of the fish. A 55 cm female off
British Columbia wil'l produce about 860,000 €g9s, whereas an 80 cm
female will produce about 3,350,000 eggs (Thompson 1,962, Forrester
1e6e).
Thompson OgAZ) found that the l ength-fecundi ty . re'lati onshi p for
cod jn Asian waters (Sakhalin and West Kamchatka) was the same as
that for cod in British Columbia waters.G. Incubation Period
Pacific cod eggs are demersal (develop on the ocean floor). The
rate of development is affected by temperature (Forrester and
Alderdice 1966). Hatching takes place in 11.5 days at 8oC, blt
about 28 days are needed for hatching at 2"C (Forrester 1969).
Larvae are found in coastal areas at depths of 25 to 150 m' wjth
the majority occurring between 75 to 100 m (Mukhacheva and
Zvyagina 1960). Larvae (8.8 to 11.6 nrn in'length) have been found
in- Biring Sea plankton in June and July (Musienko 1963) and in
Cook Inlet (5.3 to 9.0 mm in 'length) in May and Ju1y. Larvae of
unspecified lengths were found in Kodiak Bays in April and May
(Rogers et al. 1979) and in March-Apri1 and June-July on the
Kodiak shelf (Kendall et al. 1980).
VI. MOVEMENTS ASSOCIATED WITH LIFE FUNCTIONS
In the Bering Sea, age 0 (1ess than one year) cod are found in coastal
waters. As the fish grow they move to progressively deeper, less
coastal water, with age one fish found in inner continental shelf
waters, d9€ two and three on the central shelf, and age four and older
on the outer shelf (Bakkala 1981).
Paci fi c cod fol I ow short ( 300 to 500 km) seasona'l mi grati ons.
Generally they move into deeper (110 to 128 m) waters to spawn in late
winter (January to April). After spawning, the movement is generally
322
jnto more shallow (ll to 55 m) areas. The extent and direction of
these migrations are probably control led more by temperature and
location bf food than by depth (Alderdice and Forrester I97I, Ketchen
1e61 ) .
VII. FACTORS INFLUENCING POPULATIONSA. NaturalLittle information is available on predators of Pacific cod;
however. hal i but ( Hi ppoql ossus stenol epi s ) , fur seal s (lq]lotljru!
ursinusi, u.tukha'wEiieflD4pn@), and sperm rJh'a'ies
lPhysedi macrocephalus) rrffi to feed on gadoids
(@n1e76).
Qcean currents and weather patterns that carry I arvae i nto
productive areas and that result in a concentration of plankton
are probably important for survival of cod larvae (Cooney et al.
1e79).B. Human-relatedA summary of poss'ib1e impacts from human-re'lated activities
includes the fol lowing:
" Alteration of preferred water
oxygen, and chemical composition
temperatures, pH, dissolved
" Introduction of water soluble substanceso Increase in suspended organic or mineral materia'lo Reduction in food suPPlYo Human harvest
" Seismic shock waves
(See the Impacts of Land and Water Use volume of this series for
additional information regarding 'impacts. )
VIII. LEGAL STATUS
Pacific cod within the 200 mi limit are managed by the North Pacific
Fishery Management Council (NPFMC) through their groundfish fishery
management p1ans. More details of management status can be found in
the pollock Human Use section of this document.
IX. LIMITATIONS OF INFORMATION
Population dynamics of the Pacific cod are not thoroughly understood
because of the few years for which good biological assessment data are
available (Bakkala 1981). Such information is important for improved
management and protection of the resource.
REFERENCES
Alderdice, D.F., and C.R. Forrester. 1971. Effects of salin'ity, tempera-
ture, and dissolved oxygen on early development of the Pacific cod
(Gadus macrocephalus). J. Fish. Res. Bd. Can.28:883-902.
Bakkala, R. 1981. Pacific cod of the eastern Bering Sea.
NOAA, Seattle, l.lA. 49 pp.
323
NWAFC, NMFS,
C'lausen, D.M. 1981. Summer food of Pacific cod, Gadus macrocephalus, in
coastal waters of Southeastern Alaska. Fish. Bull. 78:968-973.
Cooney, R.T., C.P. McRoy, T. Nishiyama, and H.J. Niebauer. 1979. An
example of possible weather influence on marine ecos_y_s_tem processes.
page! 697-707 in B.R. Melteff, ed. Alaska fisheries: 200 years and 200
mi'les of change. Proceedings of the 29th Alaska science conference,
Aug. 15-17, 1978, Fairbanks, Ak. Alaska Sea Grant Rept. 79'6.
Forrester, C.R. 1969. Life history information on some groundfish species.
Fish. Res. Bd. Can. Tech. Rept. No. 105. 13 pp.
Forrester, C.R. , and D. F. Alderdice. 1966. Effects of sal inity and
temperature on embryonic development of the Pacific cod (gadrJs
macrocephalus). J. Fish. Res. Bd. Can. 23:319-340. Cited in
filGnlice and Forrester I97I.
Hughes, S.E. L974. Groundfish and crab resources in the Gulf of Alaska- based on International Pacific Ha'libut Commission trawl surveys' May
1961 - March 1963. USDC: N0AA, NMFS, Seattle, l.lA. Data Rept. 96.
Jewett, S.C. 1977. Alaska's latent fishery - Pacific cod. Ak. Seas and
Coasts 5:6-8.
. 1978. Summer food of the Pac'ific cod, Gadus macrocephalus' near-Tliiak Island, Alaska. Fish. Bull. U.s. 76:700-706.
Kendall, A.lrl., Jr., J.R. Dunn, R.J. Wolotira, JF., J.H. Bowerman, Jr.r DrB.
Dey, A.C. Matarese, and J.E. Munk. 1980. Zooplankton, inclug!!g
ichthyoplankton and decapod larvae, of the Kodiak shelf. USDC: N0AA'
NMFS,- NWAFC. Ann. rept. RU-551. Cited in Rogers et a]. 1980.
Ketchen, K.S. 1961. Observations on the ecology of the Pacific cod (Gg9us
macrocepha'lus) in Canadian waters. J. Fish. Res. Bd. Can. 18:513-558.
Low, L.L. 1974. A study of four major groundfish fisheries of the Bering
Sea. Ph.D. Dissert., Univ. Washington. July L974. 240 pp.
Moiseev, P.A. 1953. Cod and flounders of far-eastern seas. Izvestiya
tttlRO qO: L-287. (Transl . from Russian by F'ish. Res. Bd. Can. Transl.
Ser. No. 119). Cited in Alderdice and Forrester l97I and in Sa'lveson
and Dunn L976.
Morrow, J.E. 1980. The freshwater fishes of Alaska. Anchorage' AK:
A'laska Northwest Publ ishing Co. 248 pp.
Mukhachevd, V.A., and 0.A. Zvyagina. 1960. Development of the Pacific cod,
Gadus morhua macrocephalus. Til. Acad. Nauk. USSR Tr. Inst. 0keanol.
3TT4s:I65. fTrj h. Res. Bd. Can., Nanaimo, B.c. ) Cjted in
Salveson and Dunn L976.
324
Musienko, L.N. 1963. Ichthyoplanton of the Bering Sea (data of the Bering-- -Sea expedition 1958-195-9)'. Pages 25I-286 _in P.A. Moiseev, ed. Sov'iet
fisheries investigations in the northeasterri-Pacific, Part I. (Transl.
Israel Prog. Sci.- Transl., Jerusalem, 1968). Cjted in Rogers et al.
1980.
. 1970. Reproduction and development of Bering Sea- fishes. Pages
--l|6-;t-ZZq in p.A. Moiseev, €d. Sov'iet fisheries investigations in the
noitneasiern Pacific, Pirt V. (Transl. Israel Prog. Sci. Transl ',
Jerusalem, 1968). Cited in Salveson and Dunn L976.
Reeves, J.E. 1972. Groundfish of the Gulf of Alaska. Page.s- 411-445 in
D. Rosenberg, ed. A review of the oceanoglaphy and renewable resources
of the norifrern Gulf of Alaska. Univ. Alaska, Inst. Mar. Sci. Rept.
R72-23, A'laska Sea Grant Rept. 73-3.
Rogers, B.J., M.E. Wangerin, K.J. Garrison, and D.E. Rogers. 1980.-"- ipipelagic meroplankion, juvenile fish, and forage fish:^..djstribution
airO'retitive abundance in coastal waters near Yakutat. RU-603_. Paggs
1-106 in Environmental assessment of the Alaskan continental shelf.
Flnaf fEports of principal investigators. Vol . L7: Biological studies.
USDC: N0AA.
Rogers, D.E., D.J. Rabin, B.J. Rogers, _K.J.. Garrjson, and M.E. Wangerin.'tglg. Seasonal composition and food web re'lationsh_ips of marine
organisms in the nearshore zone of Kodjak Island - includlng ichthyo-
plinkton, merop'lankton (shellfish), zooplankton, and fish. Univ.
i,lashington, Fish. Res. Inst. Ann. rept. RU-553. 29L pp. Cited 'in
Rogers et al. 1980.
Ronholt, 1.1., H.H. Sh'ippen, and E.S. Brown. L977. Demersal fish and
strettfish resources'ot tne Gulf of Alaska from Cape Spencer to Unimak
Pass 1948-1976. A hjstorical review. Vol. 3. Pages 624-955 i1
Environmental assessment of the Alaskan continental - shelf. FinaT
reports of principa'l investigators. Vol . 2: Bio'logical studies. USDC:
NOAA, ERL, OCSEAP.
Salveson, S.J., and J.R. Dunn. I976. Pacific cod (fami'ly Gad'idae). Pages
393-405 in tl|.T. Pereyra, J.E. Reeves, and R.G. Bakkala.(principal
i nvesti gafirs ) , Demersal f ish and shel I f i sh resources of the eastern
Bering "Sea in-the Baseline year 1975. USDC: N0AA, NMFS' Northwest
Fisheries Center processed rept. 619 pp.
Teshima, K. 1983. Relationships between catch per hour trawled of Pacific
cod and water temperature'in winter season in the eastern Bering Sea.
paper No. C-2. 'Presented at the 1983 INPFC Groundfish Symposium'
Anchorage, AK, 26'28 lct. 1983. 7 pp. + figures.
325
)-
Thompson, J.A. 1962. 0n the fecundity of Pacific cod (G_adus macrogqphalus)'from Hecate Strait, British Columbia. J. fiih. neilEfeEn'.
19(3):497-500. Cited in Sa]veson and Dunn 1976.
Yamamoto, G., and C. Nishioka. 1952. The development and rearing of
hatiheO larvae of North Pacific cod (Gadus macrocephalus Tilesius).
Pages 301-308 in Jap. Sea Re.g. Fish. .Tgs. L;5;5ec. Publ. on 3rd
Anniversary ofTts founding. (Transl. from Japanese by Fish. Res. Bd.
Can. Transl. Ser. No. 402). Cited in Alderdice and Forrester 1971.
Zenger, H.H., and N.J. Cummings. 1982. Pacific cod. Pages 88-110 in-.1. gatsi-ger, ed. Condition of groundfish resources of the Gulf oT
A'laska in 1982. Unpubl. rept. USDC: NWAFC, NMFS, N0AA, Seatt'le, t,lA.
198 pp.
326
Pacific Halibut Life History and Habitat Requirements
Southwest and Southcentral Alasha
1. Range of Pacific halibut (IPHC 1978, Best 1981, Bel'l and
Pierre 1970)
NAMEA. Connon Name: Pacific halibutB. Scientific Name: Hippoglossus stenolepis
RANGEA. Worldwide
Pacific halibut are distributed on the continental shelf of the
North Pacific 0cean from Santa Barbara, California, to Nome,
Alaska. They are also found along the Asiatic Coast from the Gulf
of Anadyr to Hokkaido, Japan (IPHC 1978).B. Regional Distribution Sunmary
To supplement the distribution information presented in the text,a series of bluelined reference maps has been prepared for each
r20I'lO
Map
st.
I.
II.
327
region. Most of the maps in this series are at 1:250,000 sca1e,
but some are at 1:1,0001000 scale. These maps are availab'le for
review in ADF&G offices of the reg'ion or may be purchased from the
contract vendor responsible for their reproduction. In addition,
a set of colored 1:1,000,000-scale index maps of selected fish and
wi'ldlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.
1. Southwest. The largest concentrations of halibut are in the
6lT-0Tll aska, wi th a smal I er popul ati on i n the Beri ng Sea
(Best 1981). In the Gu'lf of Alaska, halibut abundance is
highest in the Kodiak Island area (Ronholt et al. 1977,
Webber and Alton I976). (For more detailed narrative
information, see volume 1 of the Alaska Habitat Management
Guide for the Southwest Region. )2. Southcentra'1. Pacific halibut stocks are located throughout
me ffiIfiGntral region. More detailed information is
presented in the halibut Distribut'ion and Abundance narrative
found in volume 2 of this publication. (For more detailed
narrat'ive informat'ion, see volume 2 of the Alaska Habitat
Management Guide for the Southcentra'l Region.)
III. PHYSICAL HABITAT REQUIREMENTS
Hal ibut are concentrated in areas with bottom water temperatures
ranging from 3 to 8oC (IPHC 1978). Best and Hardman (1982) note that
catches i n juveni I e hal i but surveys were usua'l 1y 'larger when bottom
water temperatures were near 4oC. The bathymetric range for adult
halibut is between 27 and 1,100 m (Rogers et al. 1980, IPHC 1978).
IV. NUTRITIONAL REQUIREMENTSA. Food Species Used
Hal ibut are opportunistic feeders, using whatever food is
available (Best and Hardman 1982). Ha]ibut less than 10 cm in
length feed primari'ly on small crustaceans, mainly shrimp and
small crabs (Smith et al. 1978). As the size of the halibut
increases, the frequency and size of fish in the diet also
increases. Best and Hardman (1982) found, in a survey of stomach
contents of young halibut main'ly between 10 and 80 cm in 'length,
that species important in the diet were Tanner crab (!hionoecetes
bairdi ), hermit crab (Paguridae) , sandf ish (TrichodonTlch
B.
Uqllul/t llgrllltL vlqv \lqyql lvus/t JqrrvrrJrr \rr r!
Gnd--Tiirce (Ammodytes
.
hexapterus ) , and wa'l I eye-fficn-lfn", .qg.g
chal cogramma fTrgerlaTT6ut 'Feed on shrimps , crabs , and f i shchalcogramma). Larger halibut feed on shrimps, crabs, and fish
lETfeTT-aT[sand lances) (Smith et al . 1978), Ir the Gulf of
Ala!ka, halibut feed 'largely on Tanner crab (Chionoecetes spp.)
octopui , Paci f i c cod (Egrt macrocephal us ) , aTd arrowFooth
f louhder (Atheresthes stomTaT)-(BesT, pers. comm. ).
Type of FeeTr nlAreas Imf-
Adult halibut feed both on benthic and pelagic organisms as they
move on and off the continental shelf (Gusey 1978).
328
V.
C. Factors Limiting Availability of Food
Growth rate information indicates that food may be a limiting
factor when halibut abundance is high (Schmitt and Skud 1978).
Apparent'ly, large numbers of halibut can cause a significant
reduction of their food supply.D. Feeding Behavior
Halibut feed year-round, but large halibut feed less in winter
than in summer (WeUber and Alton 1976).
REPRODUCTIVE CHARACTERISTI CSA. Reproductive Habitat
Spawning individuals concentrate along the continental shelf at
depths fron 228 to 456 m. Some spawning also occurs at many other
locations (Bell 1981). Major spawning sites in the Southcentral
Region include areas along the continental shelf east and west of
Middleton Island, south of Cape Cleare, and in Amatuli Trough (St.
Pieme, in press).B. Reproductive Seasonal ity
In the Gulf of Alaska, breeding takes p'lace from November to March
(IPHC 1978). In the Bering Sea, Novikov (tg6+) reported spawning
from 0ctober to March.C. Age at Sexual MaturityIn the Gulf of Alaska, most males are mature by age 8; average
maturity for females is age LZ (IPHC 1978). Best (tget) reported
age at 50% maturity for females in the Bering Sea to be 13.8 yr,
at a length of I22 cm. Males in the Bering Sea averaged 7.5 yr
and 72 cm at 50% maturity.D. Frequency of Breeding
The long (approx'imately L?-yr) immaturity of fema'le hal ibut has
apparently caused some confusion over the frequency of spawning.
Vernidub (1936), and Novikov (1964) both reported that females
spawned at most once every two years. Bell (1981), however,
stated that spawni ng occurs annua'l 'ly. Be'l I specul ated that
Vernidub and Novikov's reports $rere based on immature females with
devel opi ng ova that were caught i n trawl surveys after the
spawning period and mjstaken for nonspawning adults.E. Fecundity
The number of eggs produced per female is related to size. A
23 kg female produces about 500,000 e99s, whereas a 113 kg fema'le
may produce 4 million eggs (IPHC 1978).F. Incubation Period
Eggs hatch after about 15 days (Thompson and VanCleve 1936,
VanCleve and Seymour 1953); however, this rate of development is
related to temperature. In laboratory experjments, Forrester and
Alderdice (1973) found that at 5'C 50% of eggs hatch in 20 days,
but at 8"C 50% hatch in 12.5 days. At 2,4,10, and 12'C the eggs
did not survive to hatching.
329
1
VI. MOVEMENTS ASSOCIATED t^JITH LIFE FUNCTIONSA. Eggs and larvae of halibut are heavier than surface sea water anddrift passively in deep ocean currents, general'ly at depths of 90to 180 m, but down to 686 m. In the Gulf of Alaska, eggs and
larvae are transported great d'istances by westward ocean currents
(IPHC I978, Gusey 1978). As the larvae grow, their specific
gravity decreases. Thompson and Van Cleave (1936) reported that by
the age of three to five months all larvae were in the upper 100m. Larvae are moved by prevai'ling winds to the shallow (about 12
m) sections of the shelf (Gusey 1978, Thompson and Van Cleave
1936). Juveniles settle to the bottom at about six months old and
remain in nearshore waters for one to three years (IPHC 1978, Best
and Hardman 1982).
Halibut move from deep water (up to 1,097 m) along the edge of the
continental shelf to shallower (27 to 274 m) banks and coastal
waters to feed during the summer (IPHC 1978). The halibut returnto deep water in the winter to spawn. These movements and
coastwide migrations, which may encompass hundreds of miles, have
been documented by extensjve IPHC tagging studies. A high
proportion of adults tagged jn the Bering Sea were recovered in
the Gulf of Alaska, but no recoveries of adults released in the
Gulf of Alaska have been made in the Bering Sea (Bell 1981).
VII. FACTORS INFLUENCING POPULATIONSA. NaturalLittle is known about predation on halibut. Sea lions often prey
upon ha'libut hooked on'longline gear, but it is un'likely that they
are any threat to free-swimming halibut (Bell 1981).
Eggs, larvae, and juvenile halibut probab'ly fa'I1 prey to many fish
species, but older halibut, because of their size, must be safe
from predation by most animals, except possibly large marine
manmals (Webber and Alton 1976).B. Human-rel atedA summary of possib'l e impacts from human-rel ated acti vi ties
i ncl udes the fol 'lowi ng:o Alteration of preferred water temperatures, pH, djsso'lved
oxygen, and chemical composition" Introduction of water soluble substanceso Increase in suspended organic or mineral material
" Alteration of preferred substrateo Reduction in food supply" Human harvesto Seismic shock waves
(See the Impacts of Land and Water Use volume of this series for
additional impacts information. )
VI I I. LEGAL STATUS
The International Pacific Halibut Commission (IPHC) manages the Pacifjc
halibut fishery. The commiss'ion monitors catch and effort, restricts
gear and size of fish landed, and defines fishing areas. The North
330
Pacjfjc Fishery Management Council includes Pacific halibut in their
list of unallolated ipec'ies that must be avoided by groundfish fleets
and includes in their Gulf of Alaska Groundfish Management Plan
time-area closures designed to minimize incidental catch of halibut.
Further details of management status are included in the halibut Human
Use section of this document.
IX. LIMITATIONS OF INFORMATION
Best ( 1981) suggested that more information is needed concerning
juveniie halibuCmovements and the similarities and differences between
the Bering Sea and Gulf of Alaska stocks.
REFERENCES
Bell, F.H. 1981. The Pacific halibut the resource and the fishery.
Anchorage, AK: Alaska Northwest Publishing Company. 267 pp.
Best, E.A. 1984. Personal communication. Senior Biologist, IPHC, Seattle'
t^,lA.
. 1981. Halibut ecology. Pages 495-508 in D.h|. Hood and J.A.-Talder, eds. The eastern Beri ng Sea shel-f, oceanography and
resources. Vol. 1. USDC: N0AA, 0MPA. 1981.
Best, E.A., and W.H. Hardman. 1982. Juvenile halibut surveys, 1973-1980.
IPHC Tech. Rept. No. 20. 38 PP.
Forrester, C.R. and D.F. Alderdice. 1973. Laboratory observations on early
development of the Pacific halibut. IPHC Tech. Rept. 9. 13 pp.
Gusey, W.F. 1978. The fish and wildlife resources of the Gulf of Alaska.
Shell 0il Company, Environmental Affairs. 580 pp.
Hoag, S.H., R.J. Myhre, G. St.-Pierre, and D.A. McCa-ughran. 1983. The- Pacific hal ibut resource and fishery in regulatory area 2. I.
Management and b.iology. Pages 5-54 in IPHC Sci. Rept. No. 67. 89 pp.
IPHC. i978. The Pacific halibut: bio'logy, fishery and management. IPHC
Tech. Rept. No. 16 (revision of No. 6). 57 pp.
Novikov, N.P. 1964. Basic elements of the bio'logy.of the.Pacifjc halibut
(Hioooqlossus hippoqlossus stenolepis Schmidt) in the Bering Sea.
iAil-Tmig i n
*F.E-ilidteevll e<I.-Tov i et f i s heri es i nves t i gat i ons _ i n
the northeast Ec'ific, Part II. (Transl. Israel Prog. Sci. Transl. 'Jerusalem, 1968).
Rogers, B.J. , M. Wangeri n, K. J. Garri son, and D. E-.- . Rogers. 1980.- Epipelagic merop'lankton, juvenile fish, and forage fish:_. distribution
aha'relative abundance in coastal waters near Yakutat. RU-603. Pages
331
1-106 in Environmental assessment of the Alaskan continental shelf.
Vol . IT2 Bi o'l ogi cal studi es. USDC: NOAA.
Ronholt 1.1., H.H. Shippen, and E.S. Brown. t977. Demersal fish and
shellfish resources'.of the Gulf of Alaska from Cape Spencer to Unimak
Pass 1948-1976, a historical review. Vol. 3. RU-174. Pages 624-955
in Environmental assessment of the A'laskan continental shelf. Final
Eports of principal investigators. Vol . 2: Bio'logical studies.
USDC: N0AA, ERL, 0CSEAP.
Schmitt, C.C., and B.E. Skud. 1.978. Re'lation of fecundity to long-term
chinges in growth, abundance, and recruitment. IPHC Sci. Rept. No. 66.
Smith, R.1., A.C. Paulson, J.R. Rose. 1978. Food and feedi_ng relationships
in the benthic and demersal fishes of the Gulf of Alaska and Bering
Sea. RU-284. Pages 33-107 in Environmental assessment of the Alaskan
continental shelf. Final rei!6rts of principa'l investigators. Vol. 1:
Biological studies. USDC: N0AA, ERL.
St. Pierre, G. In press. Locations and times of spawning for Pacific
ha1 i but. I PHC Sci . RePt.
Thompson, W.F., and R. VanCleve. 1936. Life history of the Pacific halibut'(2) distribution and early life history. Inter. Fish. Comm. Rept. 9.
Cited in Best 1981 and 'in Hoag et al . 1983.
Vancleve, R., and A.H. Seymour. 1953. The production of halibut e$_gs on
the-Cape St. James spawning bank off the coast of Britjsh Columbia
1935-1946. IPHC RePt. 19. 44 PP.
Vernidub, M.F. 1936. Data concerning the Pacific white halibut. Proc.
Len'ingrad Soc. Nat. 65:143-182. Cited in Bell 1981.
Webber, R.A., and M.S. Alton. L976. Pacific halibut (familV _P]gufo-nectidae). Pages 511-521 in W.T. Pereyra, J.E. Reeves, R.G. Bakkala,
eds. Demersal fish and shelT-fish resources of the eastern Bering Sea in
the baseline year 1975. USDC: NOAA, NMFS' Seattle, t,|A.
332
Pacific Hening Life History and Habitat Requirements
Souttrrest and Southcentral Alasha
ililIil
I.
II.
Map 1. Range of Pacific herring (ADF&G L978; Malloy, pers. comm.)
NAMEA. Comrnon Name: Pacific herringB. Scientific Name: Clupea harengus pallasi
RANGEA. Wor'l dwi deIn North &nerica, herring are found from San Diego Bay' Califor-
nia, to Cape Bathurst in the Beaufort Sea (Hart 1973). In Asia,
they range'from Taksi Bay to the Yellow Sea (Andriyashev 1954).B. StatewideIn Alaska, herring are in a continuous distribution from Dixon
Entrance in Southeistern Alaska to Point Barrow (ADF&G 1978).
," o d
333
C. Regi ona'l Di stri buti on Sunrnary
To-supplement the distribution information presented in the text,
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 -scale'bul some are at 1:1,000,000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition'
a set of colored 1:i,000,000-scale index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.
1. Southwest. Major concentrations exist in the Kodiak area'
alonq'-Th-e Alaska Peninsula and Aleutian Islands, and in
Brislol Bay. (For more detailed narrative information, see
volume 1 6f the Alaska Habitat Management Guide for the
Southwest Reg'ion. )Z. Southcentral. Major concentrations exist in Prince William
Sund and-frwer Cook In]et. (For more detailed information,
see volume 2 of the Alaska Habitat Management Guide for the
Southcentral Region. )
III. PHYSICAL HABITAT REQUIREMENTSA. Water Qual itY
In the Bering Sea, temperature may have the greatest influence on
the seasonal-distribution of herrlng (Wespestad and Barton 1981).
Dense schools of overwintering adult herring have been found at
temperatures of from 2 to 3.E"C in the Bering S.g (Dudnik. and
Usoitsev 1964). Herring moving from the overwjntering grounds in
the Bering Sea to spawning grounds have passed thrqugh qater at
subzero iemperatures (Weipestad and Barton 1981). Immature
herring may occupy less saiine waters than adults (faylor 1964).
Juveniles,- howevei, are found in a wide range of salinities in
British Columb'ia, with most concentrat'ions located at 25 parts
pers thousand (o/oo) (Hourston 1959). HerriJlg eggs.and fry were
?ound in Imuruk Basin near Port Clarence, Alaska' in water of 4
o/oo salinity (Barton 1978). Immature fish in the _Bering _Seaexhibit greater tolerance or preference for colder, 'less saline
areas onlheir overwintering grounds on the cont'inental shelf than
do adult fjsh (westpestad and Barton 1981). The t'imin9 -of
spawning in the western Beritg Sea is related to winter and spring
water temperatures, with early maturation occurring in warm years
and de1 ayed devel opment i n lol der years ( Prokhorov 1968) . _
In
Bristol guy and Port Heiden, herring appeared on the- lP9!nlng
grounds whdn temperatures reached 6"C. A temperature of 10'C has
5een documented in Bristol Bay during the spawning season (Warner
and Shafford I977). Water temperatures on Bering Sea spawning
grounds between Norton Sound and Bristol Bay have ranged between
5.6" and I 1 . 7'C ( Barton L979). Optimum temperature for egg
development in the laboratory is from 5o to 9"C. Below 5"C, eggS
Oie (Alderd'ice and Velsen 1971).
334
B. Water Quantity
Adults were found to overwinter at depths of from 107 to 137 m in
the Bering Sea (Dudnik and Usoltsev 1964). Alaskan herring move
inshore tb spawn in both subtidal and intertidal areas in the
spring. Herring remain in shallower coastal waters after spring
s'pawning in the-Bering Sea (Pereyra et al. 1976, Bakkala and Smith
1e78).C. Substrate
See Reproductive Habitat, V. A., this report.
IV. NUTRITIONAL REQUIREMENTSA. Preferred Foods1. Larvae and postlarvae. Herri.ng 'larvae and_postlarvae feed on
offipods and nauplii, small fish larvae, and
diatoms (Hart 1973). The first food eaten by 'larval herring
may be I imi ted to re1 ati vely smal I , mi croscopi c pl ankton
organisms that the larvae must nearly run into to notice and
capture. Early food items may be comprised of more than 50%
microscopic eggs (Wespestad and Barton 1979).2. Juveniles. Juveniles consume mostly crustaceans such as
copepols, amphipods, cladocerans, decapods, barnacle larvae,
and euphasi i ds. Consumpti on of some smal I fi sh ' mari ne
worms, and larval clams has also been documented (Hart 1973).
In the western Bering Sea and Kamchatka area in November and
December, the diet of juveniles has consisted of medium forms
of zooplankton (Chaetognaths, mysids, copepods, and
tunicates) (Kachina and Akinova 197?),3. Adults. In the eastern Bering Sea, August diets of adults
wElilompr"ised of 84% euphausiids, 8% fish fry, 6% calanoid
copepods, 2% gammarid amphipods; fish fry, in order of
imboitance, weie walleye pollock, sand'lance' capelin, and
smelt. During spring months, food items were mainly Themisto
(amphipoda) and Sagitta (chaetognath). After spawn'ing
(eaitern Bering SeaJ, adults preferred euphaus'i.ids, copepods
(Calanus spp.); and arrow worms (Sagitta spp.) (Dudnik qnq
USTtsev 1964). In demersal areas,EfrETh contents included
polychaete worms, bivalve mol'luscs, amphipods, copepods'juvinile fish, and detritus (Kachina and Akjnova L972).
Barton (tgZg) found cladocerans, flatworms (Platyhe'lminthes),
copepods, and cirripeds jn herring captured during spring
months. Rather than exhibiting a preference for certain food
items, adu'lt heming feed opportunistically on any large
organisms predominating among the plankton in a given area
( Kaganovski i 1955).B. Feeding Locations
Feeding occurs primarily offshore in coastal waters of the inner
continental shelf. In British Columbia, large aggregations of
herring may be scattered along 100 mi of coastline off the mouth
of Juan de Fuca Strait. These aggregations may move many miles
north or south during the sunrner, presumably fol'lowing their food
supply (Hourston and Haegele 1980). Herring remain in coastal
,r1
V.
waters during the surmer because heavy phytoplankton blooms and
poor feeding-conditions exist on the outer shelf (Rumyantsev and
barda 1970). Herring may avoid areas of heavy phytoplankton bloom
because of the low nutritional value of the phytoplankton and
because their gi11s may become clogged by certain species of
phytoptankton anA their respiration thereby affected by certain
!pLcibs of phytoplankton (Henderson 1936).
C. Factors Limiting Ava'ilability of Food
Climatic conditions and ocean currents may affect the availability
of food. 0n the rearing grounds, poor weather conditions, such as
'lack of sunshine, may O-el-ay the spring bloom of phytoplankton and
therefore the development of zooplankton on which larvae feed.
The result would be an insufficient food supply available at
hatchi ng to meet the energy needs of the 'larvae. Cuments may
carry llrvae to places where the food supply is inadequate. In
yeari where freshwater runoff is greater than normal, or wind-
iriven water transport offshore has a net southward direction,
larvae will be carried offshore away from the more abundant food
suppl ies and be exposed to additional sources 9f predation
(Hbirrston and Haegele'1980, 0utram and Humphreys 1974).
D. Feeding Behavior
Adults- general'ly feed prior to spawning and more intensively
afterwar-d (Svetovi dov 1952). Feedi ng i n the Beri ng Se.a decl i nes
during early winter, ceas'ing completely in late winter (Dudnik and
Usoltev 1964). Juvenile herring were found to feed during
November and December in the Kamchatka waters of the western
Bering Sea (Rumyantsev and Darda 1970). Exam'ination of herring
captuied during spring months from Bristol Bay to Norton Sound
revealed that ibout 95% of the stomachs were empty or contained
traces of food items. 0n1y 3.4% of the stomachs examjned were
comp'letely ful 1 (Barton 1978) .
REPRODUCTIVE CHARACTERISTI CSA. Reproductive Habitat
In' the Bering Sea, spawning occurs on rocky head'lands or in
shal low 'lagoons and bays ( ibid. ). Eggs are deposited both
subtidal'ly ind intert'ida11y on aquatic vegetation. Predominant
vegetati vL types al ong the Beri ng . Sea coastl i ne are ee1 grass
( 26stera spp. )', rockweed (Fucus spP. ) , and ribbon kel p (-Lgmi naria
sFpl-IBu.1'on' igzg) . In'p7l rrce'ili ti i am sound, broad I ei-T-[eTp;
aqarum, and 'laminaria are the primary vegetation types (Rosenthal
Tf'6). SpawnTn!-'ivity is related to water temperatures and
occurs soon afier water has become ice-free. Recorded water
temperatures are approximately 3. to 5.5"C (Scattergood_et al.
1959);6 to 10"C in'gristol Bly (warner and shafford L977)i anq
5.6'to 11.7'C on the spawning grounds between Norton Sound and
Brjstol Bay (Barton 1979). Herring north of Norton Sound spawn in
brackish bays and estuaries (Barton 1978).
336
B.Reproductive Seasonal ity
Alaskan herring are spring spawners. However, the timing of the
spawning period differs geographically. Spawning occurs- from May
through-mid June in Cook Inlet and the Kodiak area and from April
through May in Prince t^lilliam Sound (ADF&G 1978).
0n tha Beiing Sea coast, reproductive activity extends from'late
April through July in Bristol Bay and along the Alaska Peninsula,
becoming progressive'ly later to the north, and occurring from ice
breakup-through mid August in Kotzebue Sound (Wespestad and Barton
1e81 ) .
Reproductive Behavior
Upon reaching sexual maturity, adult heming move inshore to
shal low spawning grounds usua'l 1y located in shal lower waters
(Hourston and Haege'le 1980). In the eastern Bering Sea, older
herring move inshore first (Barton 1979). Shore spawning behavior
may be-the result of low temperatures in deeper water (Svetovidov
19-52). Spawning may last from a few days to several weeks (Barton
LsTe).
Environmental or physical st'imuli such as Storms, contact with
fishes, and crowding may cause a few males to extrude milt'
tri ggeri ng a spawni ng reaction by the entire herring school
(Hourston and Haegele 1980). In presence of suitable substrate,
the fish rise to the surface and mill about, extending their
genital papi'l1ae. The herring then arch their back and swim with
short rapid body movements against the substrate, making contact
with their pectoral fins and chin. Eggs or mi'lt are extruded from
the papi'llae, which also contact with the substrate (ibid.). The
extrusion of eggs appears to be impeded unless the vent is in
contact with the substrate (eelgrass, ke1p, rockweed' or other
seaweed) (Hart 1973). Females usually'lay less than 100 eggs in a
single spawning act, but repetition of the act results in multip'le
layers of eggs-on the substrate (Hourston and Haegele 1980). Eggs
are fertilized by milt broadcast or dissipated in the water by
males (ibid.). Shore spawning behavior may be the result of low
temperatures in deeper water (Svetovidov 1952). Spawning may last
from a few days to several weeks (Barton 1979).
Age at Sexual Maturity
Sexual maturity begins at age two. Most herring do not spawn
until ages three and four. By age five, 95% of the popu'lation has
matured (Rumyantsev and Darda 1970). Herring may live up to 15
years in the Bering Sea, with the strongest age classes being four
to six (Barton 1978).
Fecundi ty
Fecundity increases with increases in body length and width
(Nagasaki 1958) and appears to be greater in the.Bering Sea than
in the Gulf of Alaska (Rumyantsev and Darda 1970). Ages four to
eight in the Bering Sea produce 26.6 to 77.8 thousand eggs(ibid.). Warner and Shafford (1977) found that the fecundity of
herring from Bristol Bay ranged from 13.1 to 7I.9 thousand eggs
for herring ranging in size from 171 to 320 mm.
c.
D.
E.
337
F. Frequency of Breeding
Pacific herring breed annual'ly upon reaching maturity.
G. Incubation Period/Emergence
Eggs take 10 to 2I days to hatch, depending on the water
temperature (Wespestad and Barton 1981). In Bristol Bay, _at
temperatures of 8o to 1.1"C, 13 to L4 days are required for
hatching (Barton 1979). The optimum temperature reported for egg
development is from 5 to 9oC. Eggs die at temperatures below 5oC
(A'lderdice and Ve1sen 1971). Newly hatched larvae are about 8 mm
in size. Larvae will grow to 30 nm in 6 to 10 weeks and begin to
metamorphose into free-swimming juveniles. Larvae are at the
mercy of water currents until they deve'lop the ability to swim
(Hourston and Haegele 1980). Larvae migrate downwards during the
day and to the surface at night, fo1'lowing their planktonic food
supply (Hart 1973).
VI. MOVEMENTS ASSOCIATED hlITH LIFE FUNCTIONS AND DEVELOPMENTAL STAGES
A. Juveni I es
In British Columbia, juveniles form schools that move out of bays
as summer progresses (Taylor 1964), and the iuveniles move from
the spawning grounds to tifferent rearing areas (Hourston 1959).
In British Columbia and southeastern Alaska, juveniles feed in
coastal waters in surnmer and move to deeper water in winter
(Taylor 1964, Rounsefel I 1930). Very I ittle is known about
juvenile herring in the Bering Sea and other Alaskan waters.
B. Adul ts
Migrational patterns are specific to each area and population.
Temperature may have the greatest influence on seasonal distribu-
tion (Svetovidov 1952). Generally speaking, mature adult herring
return to offshore feeding grounds after spawning inshore during
spring, and in August or September they move further offshore into
deepei water to overwinter (Hourston and Haegele 1980).
In Alaska, the best informat'ion available regarding migration is
on herring in the Bering Sea. Adults spend about eight months
offshore (Morris 198l). In the eastern Bering Sea, populat'ions
that spawn in Bristol Bay and possibly north to the
Yukon-Kuskokwim delta are believed to migrate south along the
Alaska Peninsula to Dutch Harbor to major wintering grounds
northwest of the Pribilof Islands (Shaboneev 1965). Migration to
the winter grounds continues through September (Wespestad and
Barton 1981). Concentrations in water from 2 to 4oC on the
overwintering grounds begins in 0ctober (Bering Sea), continuing
into winter. Mature fish (adu'lts) arrive at wintering areas
before irnmature herring (juveniles) (Rumyantsev and Darda 19i0).
Concentrations of overwintering herring may shift northwest jn the
Bering Sea in mild winters and southeast during severe winters.
0verwintering herring leave the wintering area for the spawning
grounds in late March (Shaboneev 1965). After spawning, adults
remain in coastal waters to feed (Pereyra et al. L976, Bakkala and
Smith 1978). Concentrations of herring appear off Nunivak and
338
Unimak islands in the Bering Sea during August (Rumyanstev and
Darda 1970).
VII. FACTORS INFLUENCING POPULATIONSA. Natural1. Eqq stage. Mortality during egg development is estimated at
][}-lno-urston and Haegle 1980), maior causes being wave
action, exposure to a'ii, and bird predation (Taylor 1964).
Wave action can destroy both spawn and spawn substrate in
intertidal areas (Gilmer 1978). Sea bjrds have been
documented as major predators of herring eggs in the
intert'idal area. Predation by flatfish upon eggs has also
been documented (wespestad and Barton 1981). Egg survjva'l
decreases as the layers of egg deposition increase and oxygen
cannot reach the bottom layers. The number of healthy larvae
that will hatch from a deposition nine layers th'ick will very
1ike1y be less than for eggs jn the same area fou_r layers
thick- (Hourston and Haegele 1980). Environmental stress
during the egg stage also results in malformed larvae and
eventual death ( jbi d. ).2. Larval stage. Mortal ity is high for heming 'in the larval
sTage an-ilmay exceed 99%. It i s therefore at the I arval
stage that year-class strength is determjned (Hourston and
Haegele 1980).
Morial'ity of larvae may be attributed to environmental stress
on the organism during the egg stage, resulting in the
hatch'ing of incompletely developed or malformed larvae that
are not strong enough to cope with predators or the environ-
ment (ibid.). Changes in food supply as a result of
environmental condjtions specified in section III. C. of this
report will also cause larval mortality.
Predation upon larvae is intense. Predators may include combjell'ies, iellyfish, arrow worms, small salmon, and amphipods(ibid.). Cannibalism of adult herring upon larval herring
has been documented when older herring have been present on
the spawning grounds during the egg-hatch period (jbid.).-
3. Juvenile and immature stage. The rate of natural morta'li!V
ge (WesPestad and Barton 1981).
Hourston and Haegele (1980) estimate the mortality rate of
herring in the juvenile stage at 20%. Juvenile herring are
suscepiible to predation by fish (salmon or dogfish)_, marine
mammais, and seabirds. Food availability 'is no 'longer a
1 imitin! consideration at this I ife stage (ibid. ). Thg
greater- size of immature herring (herring -in their second
year of I i fe ) woul d render them I ess vul nerabl e to the
predation suffered at earlier life stages (ibid.).
4. Adult. The natural mortality of adult herring is about 30%
Ti51T.). The probabifity of mortality increases with d9€,
particular'ly for males. Mortality rates increase at age five
as a consequence of senility, disease, and spawning mortality
339
(lJespestad and Barton 1981). Mature herring -a.re most
susceptible to predation by marine mammal s, dogfish, and
seab'irds on the spawning grounds and during migration to
their offshore feeiing giounas (Hourston and Haegele 1980).
Herring are a very important staple in food webs, and jn the
Bering-Sea they serve as a dietary staple for marine mammals,
uirds, and groundfish (lllespestad and Barton 1981). Natural
mortality of herring through all. life.stages in the Bering
Sea has been estimated to be 47% (ibid.).
B. Human-rel atedA sunmary of possible impacts from human-related activities
includes the fol lowing:o Alterat'ion of preferred water temperatures, PH'
oxygen, and chemical comPositiono Alteration of preferred substrateo Alteration of intertidal areaso Increase in suspended organic or mineral materia'lo Reduction in food suPPlyo Reduction in protective-cover (e.g., seaweed beds)o Obstructjon of migrat'ion routeso Shock waves in the aquatic environment
" Human harvest
(See the Impact of Land and Water Use volume of this series for
additjonal impacts information. )
VIII. LEGAL STATUSA. Managerial AuthoritY
Herring are managed within the 3-mi limit by the State of Alaska
Department of Fish and Game and in the Fisheries Conservation Zone
(3'to 200-mi limjt) by the U.S. Department of Commerce, National
Marine Fisheries Service, as directed by the jo'int policy of the
State of Alaska Board of Fisheries and the North Pacific Fisheries
Management Counci I .
IX. LIMITATIONS OF INFORMATIONLittle is known about the larval and juvenile biology of herring in
Alaskan waters. Overwintering areas, feeding areas, migration routes'
and stock definition have yet to be established.
. 1980. Annual management report - Chignik
Div. Cornmer. Fish., Kodiak.
2 [R. F. Mcl ean and
Management Area.
. 1981a. Annual management report - Alaska Peninsula/Aleutian
-Tdlands.
Div. Cornmer. F'ish., Kodiak.
di ssol ved
REFERENCES
ADF&G. 1978. Al as ka ' s fi sheri es atl as . Vol .
K.J. Delaney, comps.]. 43 pp. + maps.
340
. 1981b. Annual management report - Chignik Management Area. Div.
---T6-nrmer. Fish., Kodiak.
. 1982a. Annual management report - Alaska Peninsula/A'leutian
-Trlands
Management Area. Div. Commer. Fish. ' Kodiak.
. 1982b. Annual management report - Chignik Management Area. Div.
T-mmer. Fish., Kodiak.
. 1982c. Annual management report - Kodiak Management Area. Div.
---E-mmer. Fish., Kodiak. 315 PP.
. 1982d. Pacific herring stocks and fisheries in the eastern
-Blring
Sea, Alaska L982. Rept. to the Alaska Board of Fisheries, Div.
Commer. Fish., Anchorage. 2I PP.
. 1984. Management plan to regulate the herring roe on kelp
--fia-rvest
i n the Bri itol Bay' area. Al aska Board of Fi sheries , Juneau. I
p.
Alderdjce, D.F., and F.P. Velsen. L971. Some effects of salini-t-y qld
temperature on early development of Pacific herring (ClupEa pgllasi).
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1981.
Andriyashev, A.P. 1954. Fish of northern Soviet seas. Izdatelstvo. Akad.-Nauk. USSR, Moscow. (Transl. Israel Prog. Sci Transl., Jerusalem,
1e64. )
Bakkala, R.G., and G.B. Smith. 1978. Demersal fish resources of the
eastern Bering Sea: spring 1976. USDC: NWAFC. Seattle, hlA.
Barton, L.H. 1978. Finfish resource surveys in Norton Sound and Kotzebue
Sound. OCSEAP, final report (March 1976-September 1978). ADF&G, Div.
Commer. Fish., Anchorage.
. 1979. Assessment of spawning herring and capelin stocks at
-TTected
coastal areas in the eastern Bering Sea. Ann. rept. to NPFMC.
ADF&G, Div. Commer. Fish., Anchorage.
Barton, 1.H., and D.L. Steinhopff. 1980. Assessment of s_pawning h.erring
(Cluoea harenqus pallasi)' stocks at selected coastal sites in the
;ffi EeFin!-sea. Informational Leaflet No. L87. ADF&G, Div.
Commer. Fish., Juneau. 59 PP.
Dudnjk, Y.J., and E.A. Usoltsev. 1964. The herring of the eastern part.of
the Berlng Sea. Pages 225-229 in P.A. Moisev, €d. Soviet fisheries
investigations in the northeast-Pacific. Part 2. (Transl. Israel
Prog. S;i. Transl., Jerusalem, 1968). Cited in Wespestad and Barton
1979,1981.
341
Fried, S.M., C. [llhitmore, and D. Bergstrom. 1982a. Ager S€X, and size
composition of Pacific herring C]upea harengus pallasi, from eastern
Bering sea coastal spawning iiffilffia-, lgef-Ech' Data Rept'
No. 79. ADF&G, Div. Cornner. Fish., Juneau. 32 pp.
. 1982b. Age, sex, and size composition of Pacific herring Clupea
---IgfStg* pal I asi , f rom eastern Beri ng_ Sea_ _c-oast_al sp-awni ng 1!tgs '8ftffi19-6TlTech. Data Rept. No. 78. ADF&G, Div. Cormer. Fish.,
Juneau. 40 pP.
. 1983a. Age,
-hlrenqus
pal I asi ,
H-ask6, tffiT
Juneau. 32 pp.
. 1983b. Age,
--JiETenqus
pal'lasi ,
Alaska, 1964-76.
Juneau. 32 pp.
sex, and size composition of Pacific heming Clupea
from eastern Bering Sea coasta'l spawning sites 'Tech. Data Rept. No. 85. ADF&G, Div. Cornmer. Fish.'
sex, and size composition of Pacif ic heming Clupea
from eastern Bering Sea coasta'l spawning si tes,
Tech. Data Rept. No. 84. ADF&G, D'iv. Conrner. Fish.,
Gilmer, T. 1978. Cape Romanzof herring project, May Z?'June 20, 1978.
ADF&G, Div. Commer. Fish., Anchorage.
Hart, J.L. 1973. Pacific fishes of Canada. Fish. Res. Bd. Can. Bull. 180.
Henderson, G.T., C.E. Lucas, and J.H. Fraser. 1936. Ecological relations
between the herring and plankton investigated with plankton indicator.
J. Mar. Biol. Assoc. U.K.21(1):277-291. Cited in Wespestad and Barton
1981.
Hourston, H.S. 1959. Effects of some aspects of environment on the
distribution of iuvenile herring in Barkley Sound. J. F'ish. Res. Bd.
Can. 16228.
Hourston, H.S., and C.W. Haege'le. 1980. Herring on Canada's Pacific coast.
Can. Spec. Publ. Fish. Aquatic Sci . 48:23.
Kachina, T.F., and R.Y. Akinova. L972. The biology of the Korfo-Koraginski
herring in the first year of l'ife. Izv. Tikhookean. Nauchnoissled,
Inst. Rybn. Khoz. 0keanogra. Cited in Wespestad and Barton 1979.
Kaganovskii, A.G. 1955. Basic traits of behavior of pe'lagic fishes and
methods of scouting and forecasting them in Far Eastern Waters. Akad.
Nauk. SSSR., Tr. Soveshch. Ikhtiol. Kom. 5 (Trudy soveshchaniya po
voprosam povedeniya i razvedki ryb 1953): 26-33. (Transl. Natl . Mar.
Fish Sev. Biol. Lab., Honolulu, HI). Cited in Wespestad and Barton
1979.
Ma11oy, L. 1983-1984. Personal comrnunicat'ion.
Bi o'l ogi st, ADF&G, Di v. Commer. Fi sh. , Kodi ak.
342
Westward Regional
McBride, D., D. Whitmore, and D. Bergstrom. 1981. _f9e.' .Lex' and size
composition of Pacific herring, Clripea haLengus pallasi. (Va'lenciennes),
froin selected coastal spawningTites-Ton-g the eastern Bering Sea
1979-1980. ADF&G, Tech. Data Rept. No. 61. 57 pp.
Morris, B.F. 1981. An assessment of the'living marine res-ources of the
central Bering Sea and potential resource use conf'l icts between
commercial fis-heries and petroleum development in the Navarin Basin'
Proposed Sale No. 83. USDC: NMFS, EAD. Anchorage. 232 pp.
Nagasaki, F. 1958. The fecundity of Pacific. herring (glugea plf 1ti) ^in- grii'ish Columbia coastal waters. J. Fish. Res. Bd. Can. 15:313-30.
Cited in Wespestad and Barton 1981.
gutram, D.N., and R.0. Humphreys. L974. The Pacific herring in British
Columbia Waters. Fisli. Mar. Serv. Can. Pac. Biol. Sta. Cir. 100.
Nana'imo, B.C.
prokhorov, V.G. 1968. Winter period of life of herri!9 in_ the Bering Sea.
Proceedings of the Pacific Scientific Research of F'isheries and
0ceanograptry Oq:329-338 (In Russian. Transl. 1970, Fish. Res. Bd. Can.
Transl . Ser. 1433).
Rogers, D.E., K.N. Schnepf, and P.R. Russell. 1983. Feasibility of using" siale analysis methods to 'identify Bering Sea herring stocks. Univ.
Washington, Scnoot of Fisheries, preliminary rept. to NMFS. Contract
No. B3-ABC-00165. 24 PP.
Rosenfell, G.A. 1930. Contribution to the biology of t!9 Pacific heming'
Clupea Paliaii and the condition of the fishery jn Alaska. Bull. U.S.
Bffi.-FiTh-. 4 5:227 -320 .
Rosenthal, R.S. 1978. An investigation of the herring o! seaweed fishery
in Prince h|illiam Sound, Alaska: est'imates of standing crop, growth
rate of ke'lps and patterns of recolonization in harvested areas.
Alaska Coastal Research Job No. 0cean-04'78. 45 pp.
Rowell, K.A. 1980. Separation of spawning stocks of Bering- Sea herring
based on scale growth patterns. Pages 262-263 in B.R. Metleff and V.G.
Wepestad, eds. -Proceebings of the Alaska herring symposium. Sea Grant
Rept. 80-4.
Rumyantsev, A.I. and M.A. Darda. 1970. Summer herr.ing in the eastern" Berin! Sea. Pages 409-441 in P.A. Moiseev, €d. Soviet fisheries
invesligations i; the northeaEern Pacific, Part V. (Transl. Israel
Prog. Sii. Transl., Jerusalem, 1972).
Scattergood, 1.trl., C.J. Sindermann, and R.E. Skud. 1999, -spawning^9I North
Am6rican heiring. Trans. Am. Fish. Soc. 88(3):164-8. Cited in
Wepestad and Barton 1981.
343
Shaboneev, I.E. 1965. Biology and fishing of heming in the eastern part
of the Bering Sea. Pages 130-154 in P.A. Moiseev, €d. Soviet fisheries
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the origin of herring in the Dutch Harbor fishery. Univ. Washington'
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shel t: oceanogft-phy and resources. Vol . 1 . USDC : NSAA, 6MPA.
344
Pacific Ocean Perch Life History and Habitat Requirements
Soutlrwest and Southcentral Alasha
I tlo
Map 1. Range of
rto tao
Pacific ocean perch (t'taior and Shippen 1970)
I.
II.
NAMEA. Common Name: Pacific ocean perch
B. Scientific Name: Sebastes alutus
RANGEA. Worldwide
Pacific ocean perch are found alongof the Pacific Ocean from Southern
Alaska, a'long the Aleutian chain to
Sea.B. Regional Distribution Surrnary
the eastern and northern rim
California to the Gulf of
Kamchatka, and in the Bering
To supplement the distribution information
a series of bluelined reference maps has
region. Most of the maps in this series
presented in the text,
been prepared for each
are at 1:250,000 sca'le,
345
but some are at 1:1,000,000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition,
a set of colored L:i,000,000-scale jndex maps of selected fish and
wildlife species has been prepared and may be found in the At'las
that accompanies each regional guide.
1. Southwest. Chikuni-(1975)-defined two stocks of perch in the
E6FTig-Taa: the Aleutian stock, found on both sides of the
Aleutian archipe'lago, and the eastern slope stock. The
Aleutian stock'is much larger than the eastern s'lope stock.
(For more detailed narrative information, see volume 1 of the
Alaska Habitat Management Guide for the Southwest Region.)
2. Southcentra!. In --th_e _Apli I -O_ctober I973-1976 N0AA trawl
suTVE/s oT-fhe Gulf of A'laska, Pacific ocean perch were found
in eich region where sampling occurred but were generally
restrjcted to outer shelf and upper slope depth zones
(Ronholt et al. 1977). The h'ighest mean annual catch rates
of Pacific ocean perch by the Japanese trawl fi-shery .f.q[
1964 through L974'in the gu'lf .were from the area located off
Icy Bay and Yakutat BaY (ibjd.).
In-the Gulf of Alaska, feeding schools of perch are found in
the Unjmak, shumagin, Kodiak, and Yakutat regions in spring
and sunrner (Lyub'imova 1965). More detai'led distribution
i nformation i s contai ned i n the narratives on the
djstribution and abundance of Pacific ocean perch found in
volume 2. (For more detailed narrative information, see
volume 2 of the Alaska Habitat Management Guide for the
Southcentral Reg'ion. )
III. PHYSICAL HABITAT REQUIREMENTS
Adult Pacific ocean perch are genera'lly found on the continental slope
at depths of 200 to 300 m (Chikuni 1E75). Reeves (1972\ noted large
concentratj ons around submari ne canyons . Nearshore , rocky bottom
coastal areas exposed to open sea conditions and adjacent b-ays anq
straits are probably nursery areas for Pacific ocean qerch (Car'lson.and
Haight !976,' Car'lson and Slraty 1981). J.uveniles inhabit areas where
cov6r and piotection are afforded by cracks and crevices in and under
rocks and'ledges and among sessile invertebrates such as the anemone
(Metri di um seni I e ) (.Carl s.on and Straty 1981 ) .
iffin anA-T'aigEt (1976) reported that both juveniles and adults were
found only over-areas with a hard or firm substrate, never over muddy
substrate. ffrey speculated that these areas of clean substrate may be
caused by ocean-cuirents, and that current, rather than substrate type'
was a controlling factor in Pacific ocean perch habitat (i.bid.). Quast
(tglZ) also spec-ulated that distribution of adults may be determined
more by food and hydrographic conditions than by s-ubstrate.
Water temperature is an important environmental factor controlling
distribution of perch (Lisovenko 1964). Adult rockfish live within 4.0
to 6.5oC and thb young (14 to 26 cm) at lower temperatures (2.5 to
3.5"C) (Lyubimova 1964).
346
Lyubimova (1965) related the vertical distribution of perch in the Gulf
o? Alaska to the depth of the layer of oxygen deficiency (where 0,
content is less than'1 ml/l). Rockfish concentrations throughout thE
year rema1n above this layer, which varies from 350 m deep in surmer to
420 n in winter.
IV. NUTRITIONAL REQUIREMENTSA. Food Species Used
Juveniie perch of all sizes in Southeast Alaska feed on copepods
and euphaLsiids (Carlson and Haight 1976). Chikuni (1975) -notedthat itocks i n the Gul f of Al aska fed almost enti rely on
euphausiids, whereas those in the Bering Sea consume fishes'
euphausiids, and other crustaceans.
B. Types of Feeding Area Used
Slhools of feeding perch are found mainly at depths of 150 to
200 m (Lvubimova 1963).
Lyubimdvi (1964) found dense concentrations of feeding perch in
t'he western Gul f of Al aska southeast of Kodiak Is'land, southwest
of Shumagin Islands, and south of Unimak Island.
C. Factors Limiting Availability of Food
Somerton (tSZet speculated that Pacific ocean perch_may compete
with wa1'leye poliock (Theragra chalcogramma) for. food. Rapi!
growth and-survjval of 'TarvaT-rocTffifiIs wlth o-ther ocean fish
(such as po1'lock and Pacific halibut), is probably dependent on
ocean currents and weather condi tions that resul t in a
concentration of available food (Cooney et al. 1979).
D. Feeding Behavior
Skalkin (tgOq) and Luybimova (1963) state that perch in the Gulf
of Al aska feed heav'iIy from May to September and hard'ly at a]1
through the rest of t.he year. The feeding-rate changes during the
day, -being most intens'ive at noon and least intensive in the
morninS (Skalkin 1964).
V. REPRODUCTIVE CHARACTERISTICSA. Reproductive Hab'itat
Spiwning occurs in the northern Gulf of Alaska, with densities of
I arvae 'bei ng hi ghest i n the Yakutat area. .Hi gn I arval densi ties
are also folnd-in the Kodiak Island area (Gusey 1978). In the
Bering Sea, spawning takes p'lace south and southeast of the
Pribilof Islands (Paraketsov 1963).
Lyubimova ( 1964) related the location of spawning to yatgr
temperature, with females spawning in the warmer areas of the
guli. Paraketsov (1963) reported that spawning .in the Bering Sea
occurs at depths of 360 to 420 m.B. Reproductive Seasonal itYpaiitic ocean perch are-ovoviviparous, meaning t_hey are internally
fertilized and' give birth to live young.. Copulation takes place
gctober through- February, and spawni ng (rel ease_.of yo^u-ng ) -takesplace from liarch through Junb (Chi kuni 1975). Significant
347
concentrations of larvae have been reported in the Yakutat region
duri ng Apri 'l and May (Li sovenko 1964) .C. Reproductive Behavior
Natinq has not been observed (Morin and Dunn 1976); however,
LisovEnko (1964) suggested that males may copulate several times
with different females. Paraketsov (1963) repeated that mating
and ferti'l ization take p1 ace simul taneously; Chi kuni ( 1975) 'however, stated that ferti'lization may occur two months after
mati ng.
Age at Sexual Maturity
Fish f rom al I stocks beg'in to mature at age f i ve, and al'l
individuals are mature at age nine (Chikuni 1975). Fifty percent
of the stock is mature at age seven (ibid.).
Frequency of Breedingpacitic ocean perch breed annually (Morin and Dunn 1976).
D.
E.
F. Fecundity
Fecundity is hjgher in Beging Sea stocks (75,000 eggs at age 15'
205,000 it age 2o) than in the Gulf of Alaska (33,000 at age 15,
48,000 at ag6 20) (Chikuni 1975). Lyubimova (1965) reported that
10,000 to 270,000 larvae may be released.
G. Incubation Period
Spawning (release of'live young) takes place four to five months
after copulation (Cfriluni 1975).
VI. MOVEMENTS ASSOCIATED hlITH LIFE FUNCTIONS
Larval Pacific ocean perch are planktonic, with their distributjon'largely control'led by ocean currents. Sometime during their first year
of life, the juven'ile perch become demersal and are found near the
ocean bottom in areas 110 to 140 m deep (Carlson and Haight 1976' Buck
et al. 1975). When they become sexually mature, the perch move into
deeper waters (up to 320-370 m or deeper) (Buck et al. 1975).
Aduit Pacific ocean perch do not migrate'long distances (Fadeev 1968,
Chikunj 1975). Seasonal movements of perch are largely between deep
and shallow bottoms within a limited area (Fadeev 1968).
VII. FACTORS INFLUENCING POPULATIONSA. Natural
Carlson and Haight (1976) noted strong fluctuations in year class
strength. Extreme success or fai I ure of y_ear cl asses i s
apparent'ly characteristic of the species (Carl son and Haight
1976).
Lisovenko (1964) noted that fema'le perch in the Gulf of A'laska
cast their larvae in places where water currents are conducive of
high productivity. Cooney et al. (1979) have spe_culated that
weather and current condjtions resulting in dispersal of p'lankton
may have a negative affect on larval pollock surviva'|. It seems
possible that perch larvae are similarly affected.
Before heavy commercial exploitation began in the ear'ly 1960's,
Pacific ocean perch were a dominant groundfish in the Gulf of
Alaska. But perch stocks now have been severely reduced, and,
348
possi b1y as a resul t of rel ease from compet-jti on wi th perch '
iollock-have become much more abundant (NPFMC 1979)
Follock and perch feed on largely the same organisms--(Somerton
1978), and it is possible that -competition
-wi!f pollock will
prevent perch stock! from recovering even if fishing pressure is
relieved (NPFMC 1979).
Human-rel atedA Summary of possible impacts f,rom human-related activities
includes the fol lowing:
" Alteration of Preferred water
oxygen, and chemical composition
temperature, PH, di ssol ved
o Introduction of water soluble substanceso Increase in suspended organic or mineral materialo Alteration of preferred substrate
" Reduction of food suPP'lYo Seismic shockwaveso Human harvest
(See the Impacts of Land and Water Use volume of this series for
iodjtional information regarding impacts.)
VIII. LEGAL STATUS
Pacific ocean perch within the 200-mi limit are managed._b-y the_.North
Paci fi c Fi shery Management Counci I i n thei r groundfi sh fi shery
management p1ans. More details of management status can be found in
the narrative on the human use of groundfish.
IX. LIMITATIONS OF INFORMATION
Much of the available information on the biology of the Pacific ocean
perch was collected by Russian investigators jn the early l'960's,
before extensive commeicial exploitation began. Since then' stocks
have been severely reduced, and some aspects of their biology may.lgug
changed. The NPFftC recognizes a need tb improve a.nd extend_groundfish
stocI assessment surveys and to more accurately model the re]at'ionships
between organisms (including groundfish) and their environment in
Alaskan waters (NPFMC 1979).
REFERENCES
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Data Center, Univ. Alaska, Anchorage.
Carlson, H.R., and R.E. Haight. 1976. Juvenile life of Pacific ocean
peich, Sebastes alutus in coastal fiords of Southeastern Alaska: their
bnvironmen'tl-FroTfhl-Tood habjts, and school ing behavior. Trans. Am.
Fish. Soc. 105:191-201.
Carlson, H.R., and R.R. Straty. 1981. Habitat and nursery grounds of
Pacific rockfish, Sebastes gpp., in rocky coastal areas of Southeastern
Alaska. Mar. Fishl-Tev. 43(7):13-19.
B.
349-
Chikuni, S. 1975. Biological study on the population of the Pacific ocean
perch in the North Pacific. Bull.Far Seas Fish. Res. Lab. 12:1-119.
( In Japanese, Engl i sh abstract. )
Cooney, R.T., C.P. McRoy, T. Nishiyama, and H.J. Niebauer. 1979, An
example of possib'le weather influence on marine ecosystem processes.
Pages 697-70iil in B.R. Melteff , ed. A'laska fisheries: 200 years and 200
miles of change-. Proceedings of the 29th Alaska science conference,
Aug. 15-17, 1978. Fairbanks, Alaska. A'laska Sea Grant Rept. 79-6.
Fadeev, N.S. 1968. Migrations of Pacific ocean perch. Proc. Pacific Sci.
Res. Inst. Fish. and 0cean. 65:I70-L77. (Trans1. Ser. No. 1447, Fish.
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Gusey, W.F. 1978. The fish and wildlife resources of the Gulf of Alaska.
Shell 0il Company, Environmenta'l Affairs. April 1978. 349 pp.
Lisovenko, L.A. 1964. Distribution of the larvae of rockfish (Sebastodes
alutus Gilbert) in the Gulf of Alaska. Pages 2L7-225 in P.A. Moiseev,
il56viet fisheries investigations in the northeastern Pacific' Part
III. (Transl . Israel Prog. Sci. Transl. , Jerusalem, 1968. )
Lyubimova, T.G. 1963. Basic aspects of the bio'logy and distribution of- Pacific rockfish (Sebastodes alutus Gilbert) in the Gulf of Alaska.
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the northeasteFi- Pacific, Part I. (Transl. Israel Prog. Sci. Transl.,
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. 1964. Biological characteristics of the school of Pacific-ToTkf i sh (Sebastodes al utus Gi I bert) in the Gu'l f of Al aska. Pages
208-216 inT-Al-l4oFbeil-ed. Soviet fisheries investigations'in the
northeastGin Paci fic, Part I I I. (Trans'l . Israel Prog. Sci . Transl . ,
Jerusalem, 1968. )
. 1965. Main stages in the life cycle of the rockfish, Sebastodes
-fT[tus
Gilbert, in the Gulf of Alaska. Pages 85-111 jn P.A. Moiseev,
Ed.-5vent fisheries investjgations in the northeast PaCific, Part IV.
(Transl. Israel Prog. Sci. Tiansl., Jerusalem, 1968.) Cited in Rogers
et al. 1980.
Morin, M. and R. Dunn. I976. Pacific ocean perch (fami'ly Scorpaenidae).
Pages 404-424 in [.l.T. Pereyra, J.E. Reeves, R.G. Bakkala' eds.
Demersal fish anTshellfish resources of the eastern Bering Sea in the
baseline year 1975. USDC: N0AA, NMFS, Seattle, WA. 0ctober 1976.
NPFMC. L979. Fishery management plan for the groundfish fishery in the
Bering Sea/Aleutian Islands area. 160 pp.
Paraketsov, I.A. 1963.0n the biology of Sebastodes alutus of the Bering
Sea. Pages 319-327 in P.A.- Moiseev,Til. --5viet fisheries
350
investigations in the northeastern Pacific, Part I.
Prog. Sii. Trans1., Jerusalem, 1968. )
Quast, J.C. 1972. Reduction in stocks of the Pacific ocean p-e1c]n-' an
important demersal fish off Alaska. Trans. Am. Fish Soc. 101:64-74.
Reeves, J.E. 1972. Groundfish of the Gulf of Alaska. Pageg 411-455 in D.
Rosenberg, €d. A review of the oceanogrqphy and_ renewab'le resources of
the norfh-ern Gulf of Alaska. Univ. Alaska, Inst. Mar. Sci.' Rept.
R72-23. Alaska Sea Grant Rept. 73-3.
Rogers, 8.J., M.E. Wangerin, K.J. Garrison, and D.E, Rogers. 1980.- Epipelagic meroplankton, juvenile fish, and forage fish:_..distribution
ahd'relitive abundance in coastal waters near Yakutat. RU-603. Pages
1-106 in Environmental assessment of the Alaskan continental she]f.
Final report of principal investjgators. Vol . 17z Biolog'ica1 studies.
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Ronho'ft, 1., H.H. Shippen, and E.S. Brown. 1977. Demersal fish and
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Environmental assessment of the Alaskan continental shelf. Final
report of principal investigators. Vol. 2: Bio'logical studies. USDC:
NoAA, ERL, oCSEAP.
Shippen, H., and J.bl. Stark. L982. Pacific ocean perch. Pages 147-168 in-"'"J.'giiiige., - ed. condition of groundfish resources of- the Gu'lf oT'
Alaska ln tggZ. Unpub'|. rept. NWAFC, NMFS, N0AA, Seattle, hlA. 198 pp.
Skalkin, V.A. 1964. Djet of rockfish in the Bering Sea. Pages 159-174 in
p.A. Moiseev, €d. Soviet fisheries investigations in the northeast
Pacific, Part III. (Transl. Israel Prog. Sci. Transl. , Jerusalem,
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(Transl. Israel
351_
I.
II.
Sablefish Life History and Habitat Requirements
Soutlrrest and Southcentral Alasha
Map 1. Range of sablefish (Low et al. 1976)
NAMEA. Corrnon Name: SablefishB. Scient'ific Name: Anoplopoma fimbria (Pallas)
RANGEA. Worldwide
Sab'lefish are found on the Eastern Pacific coast from Mexico to
A'laska, westward along the Aleutian Island chajn and the edge of
the continental shelf in the Bering Sea, and a'long the Siberian
and Kamchatkan coasts to the northeastern coast of Japan (Low et
al . 1976).
353
B. Regional Distribut'ion Surmary
To supplement the distribution information presented in the text,
a series of bluel'ined reference maps has been prepared for each
region. Most of the maps in this series are at 12250,000 scale,
but some are at 1:1,000,000 scale. These maps are availab'le for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition'
a set of colored 1:1,000,000-scale index maps of selected fish and
wild'life species has been prepared and may be found in the Atlas
that accompan'ies each regiona'l guide.
1. Southwest. Sabl ef i sh i n the Beri ng Sea are found a'long tlt.
edgE-oT--the continental shelf but are not as abundant as in
the Gulf of Alaska. (For more detailed narrative
information, see volume 1 of the Alaska Habitat Management
Guide for the Southwest Region. )2. Southcentral. In the Gulf of Alaska, sablefish abundance is
f'-1fr:oh'es[-Trom ttre Shumigan IsIands southeastward to northern
Queen Charlotte Sound (tow et al. 1976). More details are
presented i n the sabl efi sh Di stri buti on and Abundance
narrative found in volume 2 of this publication. (For more
detailed narrative information, see volume 2 of the Alaska
Habitat Management Guide for the Southcentral Region.)
III. PHYSICAL HABITAT REQUIREMENTSA. Water Depth
Adu'lt sablefish are found at depths from 150 m down to l.'500 m.
Juvenile sablefish occupy shallower, nearshore waters (ibid.).
Sablefish larger than 340 mm are not found in nearshore commercial
catch and i ndex samp'les , i ndi cati ng that young sab'lef i sh probably
do not remajn in the nearshore zone beyond their second surnmer
(B'lackburn et al. 1983).B. Water Temperature
Kulikov (1965) stated that sablefish distribution in the Bering
Sea is controlled by temperature, with sablefish found in the
relatively warm (3 to 5"C) continental s'lope zone. Young
sab'lefish occupy a wider range of temperatures (A'lton and Webber
1976).
IV. NUTRITIONAL REQUIREMENTSA. Food Species Used
Sablefish are opportunistic feeders, consuming a wide variety of
organisms. Their djet js dependant upon their I ife . stage'
geographic location, the season, and availabi'lity of prey (Low et
al. 1976). Adult sablefish in the Gulf of Alaska feed on fish,
inc'luding wa'lleye po'l1ock (Theragra chalcogrqnmg), Arrowtooth
flounder (Atheresthes stomias),sFiny cheek roEkFr-ih (Sebastolobus
spp. ), PaCi-fiEhffii-ng-TeLpg hareirsus pal I asi i ), Pa-CTfTG-ury
(bbt oi abi as sai ra ) , and saTia--l an ) (Kennedy( bbt oi abi as sai ra ), and siTid-l anEe (TfrmodvTilq-rcpterql) ( Kennedy
aiFFTETEhET-T05Ii). Thev also feeil--o'fr-FE swiffinq and bottomanilPTeld[Er-T9-63). They al so feed'-on-Tree swTmming and bottom
dwelling invertebrates (Low et al. 1976).
354
In the Bering Sea, Shubinikov (1963) found that sablefish consume
pandal id shrimp (fandalus spp. ), _s_ea anenomes (Acti,naria)' britt'le
stars f Opniuioi'AFO, ..4' ' srnat I crustaceanTlfr[filpods and
euphausiili)-Tfr-EEdl'tion to several kinds of fish (Saffron cod,
Elbginus graciljs; Pacific cod, Gadus macrocephalus; wal'leye
ffi p;iTf i-c h ; r r i n g ; s c u I p i n i., c o-t t i da e ;jJr-1rn-eTff 'l o u n d e rs,
irleu"onectidae). Kul i-kov (1965) even noted the occasional
presence of bird remnants and seal fur in sablefish stomachs.
Voung sablefish in their pelagic stage off the coast of -Oregon-andWashington have been repdrted by Grinols and Gill.(1968) to feed
on blie lanternfish (Tarletonbeania crenul.aris), sauryl ,9n9
euphausiids. Kodolov (i@ftlso reporEi-thiilyoung sablefish
feed on Pacific saury.
Carl (1964) noted that small sablefish (36-38 cm) off southern
British Co'l'umbia gather in estuaries of rivers, where they feed on
young salmon.B. Types of Feeding Areas Used
Sibtetisfr follow a diurnal vertical migration and feed both near
the surface and in bottom water layers -(down to 1.,200 m) (Kulikov
1e6s).C. Factors Limiting Availability of Food
Little specific-information is available concerning limitations of
food auiitaUitity for sablefish. Sullivan and Smith (1982)'
however, in laboiatory experiments noted that sablefish deprived
of food for up to five months did not show any_signs of stress due
to starvatioir. They specul ated that sabl efi sh under natural
conditions may feed very infrequently and that the absence of
stress may riflect an bvolutionary adaptation to that feeding
s trategy.y{eathei- patterns and ocean currents causi ng di spersal of
planktonic organisms may have a negative effect on feeding -and'consequently, on the growth of larval sablefish, as is true of the
larvae of oiher marine fishes (Cooney et al. 1979).
D. Feeding Behavior
Shubnilov (1963) noted an annual cycle in the intensity of sab]e-
fish feedinq. He found the fullest stomachs at the beginning of
surmer (April - June), with feeding intensity decreasin_g in autumn
(August),' and ris'ing again 'in February - March. Grinols and Gil'l
(tgOg) observed feeOing sablefish and noted that they appeared.to
be "premeditated" feeders - seeking out se]ected PreYr !!enleavihg and allowing the prey to reconcentrate before feeding
again.
V. REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat
Sabtetish breed in deep waters (250 to 750 m) (Thompson 1941, Bell
and Gharrett 1945, Kodolov 1968). After spawning, the eggs rise
to the surface, where deve'lopment occurs (Alton and Webber 1976).
Bracken (1982) suggests that a large percentage o_f sablefish in
the Gulf of Alaska-may spawn in the southeastern gu'lf.
355-
Low et a'1. (1976) report that sablefish in the Bering Sea have
been observed to spawn only in the south and southeastern areas,
especia'lly in the Bower's Ridge and Aleutian Islands regions.
B. Reproductive Seasonal itY
Subinikov (1963) reported that spawning in the Bering Sea appar-
ently occurs in FebruarY.
Mason et al. (1983) found that sab'lefish along the entire west
coast of Canada spawn from January through Apri1, with peak
spawning occurring in FebruarY.
C. Reproductive Behavior
No information on reproductive behavior is available.
D. Age at Sexual MaturitY
miles mature sooner than females. The average age at 50% maturity
is five years for males and seven years for females (Low et a1.
1e76).E. Frequency of Breeding
Sabl ef i sh breed annual'lY.F. Fecundity
Fecundity is related to size, with a . smal 1 (0t cm) female
producing about 82,000 eggs and a large (98 cm) _female producing
1,277,000 eggs (Alaska Department of Fisheries 1954).
G. Incubation Period
No information on the rate of egg development is available, though
small (15.9 to 24.8 nrn) larvae have been captured in the eastern
Bering Sea in July (Kashkina 1970), approximat_ely five months
after-spawning. Juveniles are pelagic or semipelag_ic. The move
from a pelagic to more demersal existence may take place at around
30 cm (Alton and Webber 1976).
VI. MOVEMENTS ASSOCIATED t^lITH LIFE FUNCTIONSA. Timing of Movements and Use of Areas
Young- (45 mm) fish are found in shallow (70 -to 200.m)'__more
coasta'l'wateri (Kulikov 1965). As the fish get larger (45-50 cm)
they migrate to deeper waters (Bracken 1982), with adults found in
areas with aepths greater than 150 m (Alton and webber 1976).
Kulikov (1965) repbrted that sablefish follow a diurnal vertical
migration pattern, rising as high as the surface water layer
duiing the day and dropping down to the bottom layers at night.
B. Migration Routes
Yeirs of tagging studies have shown that sablefish conduct
extensive miglatibns (Bracken 1982; Pattie 1970; Phillips 1969;
Saskai 1980, cited in Bracken 1982). Until recently it was felt
that, though some fish did migrate'long d'istances, most migration
was localized (tow et al. L976). New evidence (Bracken 1982)
however, indicates that a significant number of fish (46% of those
tagged)-do migrate 'long dislances (over 185 km). Bracken (1982)
found that large fish (over 60 cm) in the Gulf of A'laska tend to
migrate eastwaid, while small (less than 60 nm) fish tend to move
weitward (possibly drifting with prevailing ocean currents). He
speculated that the change in direction of movement may be
356
associated w'ith the onset of maturity, with large numbers of adult
fish moving to the southeastern gulf to spawn (ibid.)'
VII. FACTORS INFLUENCING POPULATIONSA. Natural
The IpHC (1978) listed sablefish as a frequent_ food item of
pacific halibut (Hippoqlossus stenolepis). 0ther large predators
such as I inqcod--i3pfii-olion E]-oniaml probab'ly al so consume
sablefish (fow et'ail_I9-ZO)Ia-nA sablefish e99s, larvae and
juvenilei d". probab'ly consumed by many mo.r_e _ipecies (ibid. ).
Ftit1;ps (1969) noted-that sea lions eat sablefish, and Novikov
(1968)' noied that tagged sablefish were sometimes pursued by
seal s.
As wi th many other ocean spec'ies , the surv'ival of sabl ef i sh eggs
and larvae is dependant upon beneficial weather patterns and ocean
currents that carry them into areas where temperature. regimes and
food concentratioris are favorable to development (Low et al.
1e76).B. Human-rel atedA surnmary of possible impacts from human-related activities
j ncl udes the fo'l l owi ng:
" Alteration of preferred water temperatures, PH, dissolved
oxygen, and chemical compositiono Introduction of water soluble substances
" Increase in suspended organic or minera'l material
VIII. LEGAL STATUS
Sablefish wjthin the 200-mi limjt are managed by the North Pacific
Fishery Management Council (NPFMC) in their Gulf of Alaska Groundfish
Fishery Manajement Plan. Sablefish within 3 mi of shore are managed by
the Aliska Department of Fish and Game (ADF&G).
IX. LIMITATIONS OF INFORMATION
The extent and prevalence of migration of sablefish between management
areas has very strong implications in management of this species..
Studies of the direction and extent of movements should be continued,
along with analysis of movements by sex (Bracken 1982).
" Reduction in food suPPlYo Human harvesto Sei sm'ic shock waves
(See the Impacts of Land and Water
addjtional impacts information. )
Use volume of this series for
REFERENCES
Alaska Department of Fisheries. 1954. Blackcod research. Pages 3?-34
Annuil report for 1954. Cited in Alton and Webber 1976.
Alton, M.S., and R.A. Webber. L976. Sablefish (family Algp]opomatidae).
iages 4ZS-qZA in W.T. Pereya, J.R. Reeves, and R.G. Bakkala, Demersal
'tn
352"
fi sh
year
and shellfish resources of the Eastern Bering Sea in the base'line
t975. USDC: N0AA, NMFS, Seattle, WA. 619 pp.
Bell, F.H., and J.T. Gharrett. 1945. The Pacific Coast b]ackcod (Anoplo-
poma fi.$bria). Copeia 1945:94-103. Cited in Low et a'l . 1976-
B'lackburn, J., B. Bracken, and R. Morrison. 1983. Gulf of Alaska-Bering
Sea
-groundfish investigations. Commercial Fisheries Research and
Development Act. Proi. No. 5-49-R-1. ADF&G. Prepared for N0AA, NMFS'
Washington' DC. 85 PP
Bracken, B.E. 1982. Sablefish (Anoplopoma fimbria) migration in the Gulf
of Alaska based on gulf-wT?-TEflrdw-eries, 1973-1981. ADF&G.
Informational Leaflet No. 199. 24 pp.
Carl , G.C. 1964. Some common marine fishes. British Co'lombia Provincia'l
Museum, Dept. of Recreation and Conservation. Handbook No. 23. 86 pp.
Cooney, R.T. , C. McRoy, T. Nishiyama, and H.J. Niebauer. 1979. An examp'le
of possible weafher influences on marine ecosystem processes. Pages
697-707 in B.R. Melteff, ed. Alaska fisheriesl. 200 years and 200 miles
of change. Proceedings 29th Alaska science conference, 15-17 Aug.
1978, Fajrbanks, Alaska. AK Sea Grant Rept. 79'6.
Grinols, R.8., and C.D. Gill. 1968. Feeding behavior of
fishes .(0ncorhynchusnchus ki sutch, Trachurus syqmeficus ,
-----.'_-^
fimbria) Tromw.iFtn'ortEaast PacTTIEJ FTiF-RilBa.
IPHC. 1978. The Pacific halibut: biology, fishery and management. IPHC
Tech. Rept. 16 (rev. of No. 6). 57 pp.
Kashkina, A.A. 1970. Sunrner icthyoplankton of the Bering Sea. Pages
225-247 in P.A. Moiseev, €d. Soviet fisheries investigatjons in the
northeast- Pacific. Part V. (Transl. Israel Prog. Scj. Transl.,
Jerusalem, 1972).
Kennedy, trl.A., and F.T. Pletcher. 1968. The 1964-65 sablefish l!q9V.fiin. Res. Bd. Can. Tech. Rept. 74. 24 pp. Cited in Low et al. 1976.
Kulikov, M.Y. 1965. Vertical distribution of sablefish (Anoplopoma f]mlriq- iniftisil on the Bering Sea continental slope. Pages TSFT6filT.fE;
Moiseev, ed. Soviet fisheries investigations in the northeast Pacific.
Part IV. (Trans1. Israel Prog. Sci. Tiansl., Jerusalem,1968).
Low,1.1., G.K. Tanonaka, and H.H. Shippen. 1976. Sablefish of the north-- eastern Pacific Ocean and Bering Sea. USDC: NOAA, NMFS. Processed
rept. 115 pp.
three oceanic
and Anoplopoma
Can. 252825-
358
Mason, J.C., R.J. Beamjsh, and G.A. McFarlane. 1983. Sexual maturity'
iecundjiy and spawning of sablefish off the west coast of Canada.
page tO " in Internati-onal sablefish symposi.um- _:bstracts. Lowell
Wa[efield-Fisheries Symposia Series, 29-31 March 1983, Anchorage, AK.
Novikov, N.p. 1968. Tagging of the coalfish (Anoplopgma. finrbrja IPallas])
i n the gering- SeJ "ind" on the Paci f j c ircaitnilfamchaTka. Probl .
Ichthy. 8:762-764. Cited in Low et al . L976.
patti e , B. H. Ig7O. Two addi ti onal 'l ong-rang_e _ mi.grati ons _of sabl ef i sh
tigged in puget Sound. Washington Dept. of Fish. Tech. Rept. 5.
phillips, J.B. 1969. A review of sablefish tagging experiments in Cali-
fornia. Pac. Mar. Fish. Comm. Bull. 7.
report on J.S. blackcod tagging experiments
region and Gulf of Alaska in 1978 and 1979.
Fish Agency of Japan. 13 pp. Cited in
Sasaki, T. 1980. An interim
conducted in the Aleutian
Far Seas Fish. Res. Lab.
Bracken 1982.
Shubinikov, D.A. 1963. Data on the bio'logy of sablefish of the Bering Sea.
pages 287-296 jn P.A. Moiseev, €d.. Sov'iet fisheries investjgations-in
th6 northeast Tacific. Part I. (Transl. Israel Prog. Sci. Transl',
Jerusa'lem, i968. )
Su11ivan, K.M., and K.L. Smith . 1982. Energetics of sablefish,- Anop'loPoTa
fimbria, under laboratory conditions. Can. J. Fish. Aquat. Sci.
39'-: Ilffiz-1,020.
Thompson, W.F. 1941. A note on the spawning of the black cod (Anoplopoma
' fimbria) [Pa'llas]. copei a 4:270. Cited in Low et al . L976.
359
I.
II.
Walleye Polloch Life History and Habitat Requirements
Soutlrwest and Southcentral Alasha
Map 1. Range of walleye po'llock (Bakkala et al. 1983)
NAMEA. Corrnon Name: l.la'l I eye pol l ockB. Scientific Name: Theragra chalcogramma
RANGEA. Worldwide
Pollock are distributed from central Ca'lifornja through the Bering
Sea to St. Lawrence Island and on the Asian coast to Kamchatka,
the Okhotsk Sea, and the Southern Sea of Japan (Hart 1973).B. Regional Distribution Summary
To supplement the distribution information presented in the text,
a series of b'luelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale,
but some are at 1:1,000,000 scale. These maps are avai'lab'le for
361
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition,
a set of colored 1:1,000,000-scale index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompan'ies each regional guide
l. Southwest. In the western Gulf of Alaska, the Sanak area had
Ehe h'igfi-est mean catch per uni t effort, fo1 I owed by !h.Chirikoi and Kodiak areas, during the National Marine
Fisheries Service (NMFS) survey of L973-76 (Ronholt et al.
t977). (For more detailed narrative information, see volume
1 of the Alaska Habitat Management Guide for the Southwest
Region. )2. Southcentra-l . wa1 1ey-e po1 1 ock .had the hi gle_s! rel ati ve
appare'ienfrSundance of any species in the Gulf of Alaska from
Ciie Spencer to Unimak Pass during the NMFS survey of 1973-76(ibid.). In May-August 1975, a NMFS study team found the
highest concentrations of pollock in the northeastern Gu1f of
Aliska to be near Cape Cleare at the southern end of Montaque
Island (ibid.). More detailed information is presented in
the po1'lock Distribution and Abundance narrative found in
vol ume 2 of thi s pub'l icat'ion. (For more detai I ed narrati ve
information, see volume 2 of the A'laska Habitat Management
Guide for the Southcentral Region.)
III. PHYSICAL HABITAT REQUIREMENTS
1,1alleye pollock are schooling fish, found on or near the sea bottom as
well is it mid water and near-surface depths, although most catches are
found between 50 and 300 m (A]ton and Dei^jso 1982, Rogers et al . 1980).
Juvenile (age 0) pollock'in their first months of life are found above
the thermoci i ne' ('depth at which temperature rapid'ly decreases) 'in the
Bering Sea (Traynor 1983). Traynor (1983) also observed that age_0
pol'loik avoid deptns where water temperature is less than approximately
2.S to 3.0'C. A'ge 0 po1'lock begin to settle to the bottom in the fall
months , after wii cn they ma'in1y occupy semi demersa'l waters (Bakkal a
1e83).
Concentrations of adult walleye pollock in the Bering Sea are usua'l1y
found in water temperatures between 2 and 4'C (Serobaba 1970).
IV. NUTRITIONAL REQUIREMENTSA. Preferred FoodsIn the Bering Sea, euphausiids are the most important food for
po1'lock undei400 mm (Smith et al . 1978). -Fish ma_ke.an im.portant
tontribution to the diet of adult Bering Sea pollock' making up
70% of stomach contents by volume'in a study done by Smith et al.
(tSZe1. Pollock larvae (4.8 to 77.7 mm standard length) from.the
Beri n! Sea consume mai nly copepod naup.'l i i and 999.s and adul t
copepods (especially 0ith-ona sim'il js). (Clarke 19Zq). . Copepods
are,'however, consumed on'fflby srnaTl- ('less than 200 mm) pollock
(Smith et al . 1978, Bailey and Dunn 1979).
362
V.
Studies in the Bering Sea have shown that small (young of the year
and one-year-old) pollock comprise at__least !a% by weigh-t of the
total siomach contents of adult pollock (Dwyer et a'1. 1983.
Takahashi and Yamaguchi L972).
In the Southeastein Gulf of Alaska, Clausen (tggg) found that
small (less than 250 mm) walleye pollock ate mostly pl.anktonic
crustaceans, particularly euphauiiids, mysids, and copepods, while
large pol'loik'(larger thln 349 mm) generally ate larger p-rey, such
as ih.i*p and 'fisti. Cannibalism was observed in on'ly I% of the
stomachs; however, few po1'lock greater than 450 mm were examined.
B. Feeding Locations
Polloc[ feed mainly in the shallow (90 to 140 m) waters of the
outer continental ifrett, where tidal mixing occurs in the spring
(Serobaba !970, Salveson and Alton !976, Chang I974). Juveniles
io]low a diel vertical movement, rising to feed on zooplankton
near the surface at night (Serobaba 1970; Kobayashi 1963).
C. Feeding Behavior
In the"Berinq Sea, pollock feeding activity'is concentrated in the
summer monthi (June'- August). Pollock feed vefy.little or not at
alt during the'spawning [eri6O (nprll - mid May) (Chang 1974).
REPRODUCTI VE CHARACTERISTI CS
A. Reproductive Habitat
Poilock spawn in shallow (90. to 200 m) waters of the outer
continenta'l shelf (Smith 1981). There is also evidence that
pollock spawn in oceanic areas off the continental shelf. Oceanic
spawning iras been reported over waters 640 m deep south of.Seward,
Aiaska, and in the Aleutian basin (Blackburn' pers. comm.). Some
spawning may also occur under the sea ice (Kanamaru et al. 1979).
Siawnin! i; the Bering Sea occurs at temperatures of-1 to 3oC
(3eroba6a 1968). In Aiian waters, variability in time of spawning
is believed to be an adaptation to periods when water temperatures
are favorable for produition of abundant supplies of the initial
food of the larvae.and for'larval growth (Kamaba 1977, Nakatani
and Maeda 1983, Hamai et al. 1971). Temperature at time of
spawning is, however, apparently no,t- as important for the Shelikof
Strait - spawning population. Pol lock consistently return to
Shelikof Strait to spawn, though the temperature varies from 3.5
to 6.5"C (B'lackburn, pers. comm.; NMFS 1983).
B. Reproductive Seasonal itY
In'the Bering Sea, spawning begins in late February. Fish in the
southeastern-Bering 'Sea splwn -first. Most s.pawning occurs from
late March to mid iune, with a peak in May ('serobaba 1968). In
the western Gulf of Aiaska, Hugjhes and Hjrschhorn (1979) found
that more than 85% of po'l1ock adults had spawned prior to their
ear'liest sampling in May, indicating that most spawning occurred
in March and April.C. Reproductive Behavior
Spiwning and prespawning fish flove high in the water column,
fbrming-dense'schools (iakakura 1954, Serobaba 1974). Eggs are
363
plankton'ic and are found primari1y within 30 m of the surface
(serobaba !967 , 1974).D. Age at Sexua'l MaturitYpollock begin to recruit to the spawning population at age twot
but age classes four and five contribute most to potential
reprodilction of the population (Smittr 1981, Chang 1974),
E. Fecundity
Estimatei of individual female fecundity are difficult to achieve
because ovari es of fema'l e po1 I ock contai n oocyte popul atj ons
composed of two or three size classes. The percent,of each size
clais released during spawning is uncertain (Smith 1981, Foucher
and Beamish 1977). Serobaba (1971) found fecundities of 37,000 to
312,000 eggs per female in fish of lengths of 40 to-80 cm in the
Bering Sei. Thompson (1981) found fecundities of 199'000 to
996,660 for lengths of 32 to 49 cm off the Pacific coast of
Canada.F. Frequency of Breeding
Pol I ock breed Year'lY.G. Incubation Period
Length of incubation is dependent upon temperature. Incubation
time from fertilization to 50% hatching is 10 days at 10'C but up
to 27.4 days at 2oC (Hamai et al. 1971). Newly hatched larvae are
3.5 to 4.4 nun in length and apparently float upside-down at the
water surface (Gobunova 1954). The yolk sac is absorbed at about
7.0 to 7.5 mm (ZZ aays at 2"C) (Yusa 1954, Hamai et al. 1971).
VI. MOVEMENTS ASSOCIATED t^,ITH LIFE FUNCTIONS
A. T'iming of Movements and Use of Areas
In the Bering Sea, winter concentrations have been found between
Unimak Island and the Pribilof Islands, with some concentrations
east of the Pribilofs (Salveson and Alton 1976) and northwest of
the Pri bi'lof s al ong the conti nental s'l ope (Japan Fi shery Ag,ency
lg74). Summer feeding concentrations in the Bering Sea are found
north of the Pribilofs and to the west and northwest of St.
Matthew Island.
A major spawning concentration of pollock is found in the spring
in Sirelikbf strlit (Alton and Deriso 1982). This concentration
disperses before summer, and it is not known where that populat'ion
resides at other times of the year ('ibid.).
B. Migration Routes
In the Bering Sea, pollock follow a circular pattern of migrqtio!'tr
moving inshdre to' the shal'low (go to 140 m) waters of the
contiiental shelf to breed and feed jn the spring (March), and
moving to warmer, deeper areas of the shelf (160 to 300 m) il !!gwinter months (becember-February) (Chang L974). Hughes (I974)
noted a similar movement of po]1ock in the Gu]f of Alaska.
364
VII. FACTORS INFLUENCINGA. Natural
POPULATIONS
t,Jater temperature
growth, and survival
Pollock are a major
seals (Salveson and
fi sh.
Estimates have indjcated that in the eastern Bering Sea marine
mammals consume about 1.13 milljon tons of pollock annua11y, an
amount approximating the commercial pollock catch in that region
(faevastu and Larliins 19Bl). In Southeast Alaska, iuvenile
wa'l1eye po'l1ock are one of the most common foods of troll-caught
Pac'ific ialmon (0n!elfrJ!g-b-U! spp.) (wing 1977).
rn ttre Bering ;ea;ffi;ne [o11ock have been identified as a
major prey jtim of adult pollock. Because of this, cannibalism
mai have'an important effbct on the dynamics of the popu'lation
(Lievastu and Favorite 1981, Smith 1981, Takahashi and Yamaguchi
re72).
Cooney et al. (tgZg) suggested that weather conditions at the time
of fiist feedjng of larval pollock may be very impo-rtant for their
survival. Conditions resu'lting in a reduction of water surface
turbulence allow plankton to become concentrated and may lead to
an increased feeding efficiency (and therefore jncreased survival)
of the pollock larvae.
B. Human-relatedA summary of possible 'impacts from human-related activities
includes the following:o Alteratjon of preferred water temperatures, PH, dissolved
oxygen, and chemical comPositionn Introduction of water soluble substances
" Increase in suspended organjc or mineral materialo Reduction jn food suPPlY
" Human harvesto Seismic shock waves
(See the Impacts of Land and llat.er Use volume of this series for
additional impacts information. )
affects the 1 ength of i ncubati on, rate of
of iuvenile po'llock (Hamai et al . 1971).
Drev item for several animals, including fur
nttbn Ig76), seabirds (Hunt 1981), and other
VIII. LEGAL STATUS
Pollock within the 200-mi limit are managed by
F'ishery Management Council (NPFMC) within their
management p1an. More details of management status
pollock Human Use section of this document.
IX. LIMITATIONS OF INFORMATION
There are large gaps in the available pollock life
more information is available, however, for Bering
those in the Gulf of Alaska.
Interactjons between pollock and other species, particu'larly marjne
mammals, need to be studied (Smith 1981). A better understanding-of
movemenis of pollock stocks and interchange between stocks is also
important (ibiit.). Densjty-dependent mechanisms (such as the effect of
the North Pacific
groundfi sh fi shery
can be found in the
history information;
Sea stocks than for
365
spawning population size on age-c'lass abundance) need to be examined in
mbre delait'to help determine-the opt'ima'l population size (ibid.).
REFERENCES
Alton, M.S., and R.B. Deriso. 1982. Pollock. Pages 1-63 i! J. Balsiger'
64. Condition of groundfish resources of the Gulf of A'laska in 1982.
Unpub'l . rept. USDC: NWAFC , NMFS, N0AA. 198 pp.
Bakka'la, R., T. Maeda, and G. McFarlane. 1983. Distribution and stock
structure of pollock (Theragra chalcograqrT?) il the North Pacific
0cean. Unpub'|. rept. uffiilA-rc;N-MFJ, N0IE, 23 pp.
Blackburn, J.B. 1984. Personal communications. Commer. Fishery Biologist,
ADF&G, Kodiak, AK.
Chang, S. 7974. An evaluatior of the east_ern Be.ring Sea fishery for Alaska
popul ati on dynamics.po1 lock (Theragra chalcogrammqqra chalcogramma, Pal las):frasnl'lffiaETe, WA. 279
Pallas):
Djssert., Univ.
Gorbunova, N.N.
(Theragra
0keano'i .
Cited in
Hamai, I.K., K. Kyushin, and T. Kinoshita. I971. Effect of tempe_rature on
itre body foim and mortality 'in the developmental and ear'ly larval
pp.
Clark, M.E. 1978. Some aspects of the feeding biology of larval walleye
pollock, Theragra chalcogramma (Pallas), in the southeastern Bering
bea. Thesffi.-mffifrbanks. 44 pp.
C'lausen, D.M. 1983. Food of walleye po1lock, Theragra chalcogramma, in an
embayment of southeastern Alaska. Fjsh. BUTT. 81 (3) 2637-642.
Cooney, R.T., C.P. McRoy, T. Nishiyama, and H.J. Niebauer. 1979. An
examp'l e of poss'ib1e weather i nf I uence on mari ne ecos_ys-tem processes .
page! 697-70;;l in B.R. Melteff, ed. Alaska fisheries: 200 years and 200
miles of change. Proceedings of the 29th Alaska science conference.
15-17 August 1978. Alaska Sea Grant Rept. 79-6. Fairbanks, AK.
Dwyer, D.A., K. Bailey, P. Livingston, and M. Yang._- 1983. 99t.. pre'l'iminary- observitions on- the feeding habits of walleye pollock (Theragra
chalcogranma) in the eastern Bering Sea, based on field and'laboratory
TtfrlTE-Taper No. P-11. Presented at INPFC groundfish symposium,
26-28 lct. 1983. Anchorage, AK. 33 pp.
Foucher, R.P., and R.J. Beamish. 1977. A review of. oocyte developrnent of
fishes with special reference to Pacific hake (Merluccius productus).
Can. Fish. Mar. Serv. Tech. Rept. 755. Cited in Smith 1981.
1954. The reproduction and development of wal'leye po1'lock
chalcogramma IPallas]). Adak. Nauk, USSR, Tr. Inst.
1TT3ET9'5. (Transl. Northwest F'ish. Center, Seattle, l.lA. )
Salveson and Alton 1976.
366
stages of the Alaska pollock (Theragra chalcogranlma, Pallas). Hokkaido
Unii., Fac. Fish. guil. 22:1ffi-TiGti'-Tn-TETveson and Alton 1976;
and Bakkala, Maeda, and McFarlane 1983.
Hart, J.L. 1973. Pacific fishes of Canada. Fish. Res. Bd. Can. Bull. 180.
740 PP.
Hughes, S.E, 1974. Groundfish and crab resources in the Gulf of A'laska- based on International Pacific Hal'ibut Commission trawl surveys, Mdy
1961-March 1963. USDC: NOAA, NMFS, Seattle, WA. Data Rept. 96.
Hughes , S. E. , and G. Hi rschhorn. L979 . Bi ol ogy -o_f wa1 1 ele .
po1 'lock
'- Theragra chalcogramma, in the eastern Gulf of Alaska. Fish. Bull.
77 2263-27 4 .
Hunt, G.1., B. Burgeson, and G.A. Sanger. 1981. Feeding ecology of-seabiids of th-e eastern Bering Sea. Pages 629-647 in D.tl|. Hood,
J.A. Calder, eds. The eastern Bering Sea shelf: oceanography and
resources. Vol. 2. USDC: NOAA, 0MPA.
Japan Fishery Agency. 1974. Pacific pollock stocks in the eastern Bering
Sea. Jlpan Fiihery Agency, Tokyo, 1974. 33 pp. Cited in Salveson and
Alton 1976.
Kamaba, M. 1977. Feeding habits and vertical distribution of wal'leye
poltoc1, Theragra chalcogramma (Pallas), in the ea.r1y. life stag,e in
iJchiura Bffi'kT(alft.-REs. Inst. Pac. Fish. Hokkajdo Univ. ' Sept.
Vol.: I75-I97. Cited in Bakkala, Maeda, and McFarlane 1983.
Kanamaru, S., Y. Kjtano, and H. Yoshida. 1979. 0n the d'istribution of
eggs and larvae of Alaska po1'lock jn waters around the Kamchatka
P6njnsula, Russian SFSR, USSR. Hokkaido Reg. Fish. Res. Lab. Bull.
44zL-24. (In Japanese, English Summary). Cited 'in Rogers et al. 1980.
1963. Larvae and young of whiting, Theragra ghalcogralnma
from the North Pacific. Bull. Fac. Fish. Hokkaido Univ.
Hokkaido Univ. (in Japanese). Cited in Salveson and Alton
Laevastu, T., and F. Favorite. 1981. Ecosystem dynamics in the eastern
Bering Sea. Pages 6LL-625 in D.|ll. Hood and J.A. Calder, eds. The
eastern Bering S-ea shelf: odE-anography and resources. Vol. 2. USDC:
NOAA, OMPA.
Laevastu, T., and H. Larkins. 1981. Marjne fisheries ecosystem: its
quantitative evaluation and management. Farnham, U.K.: Fish. News
tjooks. 162 pp. Cited in Bakkalao Maeda, and McFarlane 1983.
Nakatani , T. , and T. Maeda. 1983. D'istri buti on of wal 1 eye po1 1 ock 'l arvae
and their food supply in Funka Bay and the adiacent waters of Hokkaido.
Kobayashi, K.
(Pallas)
14: 55-63.
L976.
367
Bu'll. Japan. Soc. Sci. Fish. 49:183-187. Cited in Bakka'la, Maeda, and
McFar'lane 1983.
NMFS. 1983. Cruise results. N0AA RV Miller Freeman and RV Chapman.
Cruise MF 83-01, Leg III and IV and CH83-02' Leg II. 18 pp.
Rogers, 8.J., M.E. Wangerin, K.J. Garrison, and D.E, . ROgers. 1980.- Epipelagic merop'lankton, juveni'le fish, and forage fish:_..distribution
alrd'relitive abundance in coastal waters near Yakutat. RU-603. Pages
1-106 in Environmental assessment of the Alaskan continental shelf.
Fi nal Eports of pri nci pa1 i nvesti gators . Vol . 17: Bi ol ogi ca1
studies. USDC: NOAA.
Ronholt, 1.1., H.H. Shippen, and E.S. Brown. L976. An assessment of the
demersal fish and "i'nvertebrate resources of the northeastern Gulf of
Alaska, Yakutat Bay to Cape C'leare May-August 1975. NEG0A annual
report. NMFS, NWAFC, Seattle, t.lA. Processed rept. 184 pp.
. 1977. Demersal fish and shellfish resources of the Gulf of
---TTl-ska from Cape Spencer to Unimak Pass 1948-I976. A historical
review, Vol. i. iages 624-955 in Environmental assessment of the
A]askan continental shelf. Fina'l -reports of principa'l investigators.
Vol . 2: Biolog'ica1 studies. USDC: N0AA' ERL, OCSEAP.
Salveson, S.J., and M.S. Alton. I976. Pollock (family- Gadidae).- Pages
369:391 in W.T. Pereyra, J.E. Reeves, and R.G. Bakkala, eds. Demersal
fish and-3hel'lfish rLsources of the eastern Bering Sea in the baseline
year 1975. USDC: NOAA, NMFS, Seattle, WA.
serobaba, I . l . 1967 . Spawni ng of the Al aska po] l ock
chai coqrannna ) ( Pal 'l as ) i n the northeastern Beri ng Sea. Izv .
TTkh'oofiean . Nauchno- i ss I ed. I nst. Mors k. Rybn , Khoz . 0keanogr.
(Transl. Fish. Res. Bd. Can., Transl. Ser. 3081.) 27 pp. Cited in
Salveson and Alton 1976.
. 1968. Spawni ng of the Al aska po1 'lock, TheragJa -chal cogrqnlnq
-ltr;i
t u sl-,- I n the northeas te rn Beri n g Sei . proU t .-Imifiyo .
--T': 78-0T8T
Cited in Rogers et al. 1980.
(Theragra chalcogfamma
of its fishery. Pages
(Transl. Israel
investigations in the
Prog. Sci. Transl.,
. 1971. About reproduction of wa1'leye po]1ock (Therggra
---?hat cogramma) (Pal I as ) i n the eastern part of the Beri ng Sea. Izv .
TiThbofiean.
.Nauchno-issled. Inst. Morsk. Rybn. Khoz. 0keanogr. 74:
47-55. (Transl. 1973, Fish. Res. Bd. can., Transl. ser. 2470.) 20 pp.
Cited in Salveson and Alton 1976.
(Transl. Fish. Res. Bd. Can., Transl.
. 1970. Distribution of
T-l I as ) i n the eastern Beri ng
442-45I in P.A. Moisseev, €d.
northeasFrn Pacific, Part V.
Jerusalem, I972.)
wa1 l eye po'l 'lock
Sea and prospects
Soviet fisheries
368
I974. Spawning ecologY
ramma) in the Bering Sea.
of the wa1 l eye po'l 'lock (Theragra
J. Ichthyol . 14:544-52. Cited in
STm-Ig- alveson and Alton 1976.
Smith, G.B. 1981. The biology of walleye pollock. Pages 527-551 in D.W.
Hood and J.A. Calder, eds.- ttre eastern Bering Sea shelf: oceanography
and resources. Vol. I. USDC: N0AA' OMPA.
Smith, R.1., A.C. Paulson, and J.R. Rose. 1978. Food and feeding
ielationships in the benth'ic and demersal fishes of the Gulf of Alaska
and Bering Sea. Pages 33-107 in Environmental assessment of the
Alaskan continental shelf. Final reports of principal investigators.
Vol. I: Biological studies. USDC: NoAA, ERL. June 1978'
Takahashi, Y., and H. Yamaguchi. 1972. Stock of the Alaskan pollock in the
eastern Bering Sea. -Bull. Jap. Soc. Sci. Fish 38:418-419. Cited in
Salveson and Alton 1976.
Takakura, T. 1954. The behavior of the spawning pollqcli schools recorded
Uy iish detector. Bull. Jap. Soc. Sci. Fish. 20:I0'I2. (In Japanese'
English abstract). Cited in Smith 1981.
Thompson, J.M. 1981. Preliminary report on the popul.ation biology and'fishe.y of walleye pollock (Theragra chalcog!^amma) qtl the Pacific
coast -of Canada. Can'. Tech. ReEETi5h-enA-Iquatic Sci. No. 1031.
(Theragra chalcgglamml) abundance
Sea.--Taper -No. T:TlPresented atTraynor, J. 1983. Midwater Pollock
estimation jn the eastern Bering
INPFC groundfish symposiun, 26'28 0ct. 1983. Anchorage, AK. 19 PP.
Wing, B.L. 1977. Sa'lmon food observations. Pages 20'2J- + Southeast- Alaska troll 1og book program 1976 scientific report. Alaska Sea Grant
Rept. 77-Il. Cited in Clausen 1983.
Yusa, T. 1954. 0n the normal development of the fish -(Therggfachalcogramna) (Pallas) Alaska po11ock. Hokkaido Reg. Fish. Res. Lab.
BuTll-T-0. tS pp. Cited in Salveson and Alton 1976.
369
I.
lfaflomeye Rochfish Life History and Habitat Requirements
Southcentral Alasha
Map 1. Range of ye]loweye rockfish (Hart 1973' Morrison 1982a,
Rosenthal 1983)
NAMEA. Common Name: Yelloweye rockfishB. Scientific Name: Sebastes ruberrimusc. Species Group Reprffi
Litt'le life history information is availab1e for this or any other
nearshore rockfish species in A'laska. This account is largely
derived from two nearshore bottomfish reports written by Rosenthal
et al. (tg8t, 1982).Different species of nearshore rockfish may be pelagic or
demersal, schooling or solitary. The species composition of the
rockfish community changes according to depth, with some species
found mainly in nearshore, shallow areas, and others found mainlyin deeper, offshore areas. Differences also exist in timing of
37r
life history functions, maximum age, and size of rockfish species
(Rosenthal et al. 1982).
The yelloweye rockfish is a solitary, demersa'l species found in
relative'ly deep areas, and is one of the longest-1ived. species.
Larger yelloweye rockfish may exceed 80 to 90 years (Morrison,
pers. comm.). It matures later than most species and reaches a
'l arger s i ze (Rosenthal et al . 19S2 ) .
Yelioweye rockfish is sought out by shallow water bottomfish
fishermen in Southeast Alaska and represents at 'least 50% of the
commerc'ia'l landings of that group (by numbers) (ibid. ). They also
were important in a limited .|980-1981 rockfish fishery in the
outer Cook Inlet District in Southcentral Alaska, making up
approximately 15% of that catch by numbers (Morrison .|982a).
Because of their commercial importance, yelloweye rockfish have
been chosen to represent nearshore rockfish in these accounts.
I I. RANGEA. Worldwide
Yelloweye rockfish are found from Ensenada, Baja California'
through California,Oregon, and Britjsh Columbia to Prince Wjlliam
Sound and outer Cook Inlet, Alaska (Hart .|973' Morrison I982a,
Rosenthal 1983).B. Regional Distribution SummarY
To supplement the distribution informat'ion presented in the text'
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale,
but some are at 1:1,000,000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition,
a set of colored 1:1,000,000-scale index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regiona'l guide.
Ye'l 'loweye rockf i sh are found i n nearshore and off shore areas of
Southcentral and Southeast Alaska. (More detailed Southcentral
information is presented in the rockfish Distribution and
Abundance narrat'ive jn volume 2 of the Alaska Habitat Management
Guide for the Southcentral Region. )
III. PHYSICAL HABITAT REQUIREMENTS
Yel'loweye rockfish are found in the cormercial rockfish catch in
Southeast Alaska at depths from 20 to 130 m, with the greatest number
found at depths from 75 to 130 m (Rosenthal et a'|. 1982). Gotshall
(1981) reported that yelloweye rockfish are found in depths up to 365
m. Ye1'loweye size'increases with depth (ibid.). They are found around
steep cliffs, rocky reefs, offshore pinnacles, and boulder fields
(Rosbnthal et al. 1882, Rosenthal 1983,'Carlson and Straty 1981).
372
IV.NUTRITIONAL REQUIREMENTSA. Food Species Used
Yelloweye rockfish are opportunistic feeders, consuming a variety
of organisms including fish, rock crabs, lithodid crabs, caridean
shrimps, and gastropod snails. Fish consumed include cods
(Gadidae), sand lances (Ammodytes hexapterus), herring (Clupea
harensus. Pallasi), lum'FiIEI-F (@TgFF,!eg.), and Ther
rockffih'es,-especi al 1 y Puget Sound r@ emphaeus )
and including young ydttow6ye rockfishes (Rosenffi'ET-et al.TmD;B. Types of Feeding Areas Used
Yelloweye rockfish presumably feed in rocky areas, where they are
usual ly found.C. Factors Limiting Availability of Food
Rosenthal (i983) noted extensive overlaps in the diets of many
nearshore rockfish, indicating a potential for competition among
these spec'ies .D. Feeding Behavior
Ye'lloweye rockfish have been observed to capture prey with rapid
bursts of speed (Rosenthal et al. 1982).
REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat
Spawning habitat for yelloweye rockfish has not been described;
however, Rosenthal et al. (1981) noted that rockfish (including
yelloweye) appear to move to deeper waters (2a6 m) when they reach
maturi ty.B. Reproducti ve Seasonal i ty
Rockfish are ovoviparous, meaning they are interna'l1y fertilized
and release I ive young. Morrison ( 1982b) found that female
yelloweye rockfish in lower Cook Inlet in early June contained
larvae still in early stages of development. Rosenthal (1983)
found females with pre-extrusion larvae in the northeastern Gulf
of Alaska in late June and Ju1y. Rosenthal et al. (1982) states
that females release larvae in June, July, and August in Southeast
Al aska and that mat'ing apparently takes pl ace i n 'late fal I or
ear'ly wi nter.C. Reproductive Behavior
Breeding of yelloweye rockfish has not been observed; however,
male blue rockfish (Sebastes mystinus) off the coast of California
have been observed to follow a sequence of stereotyped courtship
movements (Helvey 1982). It is possible that other rockfish'
including yelloweye, have similar breeding behavior.D. Age at Sexual Maturity
Yelloweye rockfish are late maturing. Females in Southeast Alaska
reach 50% sexual maturity at 50 to 52 cm; males reach 50% sexual
maturity at 52 to 60 cm (Rosenthal et al . 1982). Aging
techniques, which involve reading growth lines on the surface of
ye1 'l oweye otol i ths , i ndi cate that these 'l engths correspond to an
age of 1,4 to 15 years for females and 16 to 19 years for males
(Rosenthal et al. 1981). The aging technique of breaking oto'lith
V.
373
and burning the inside surface to accentuate the,growth lines
generally hls produced o'lder age estimates (Rosenthal et al. 1981;
Morrison' Pers. comm. ).E. Frequency of Breeding
Yelloweye rockfish breed annua11y.
F. Fecundi ty
Hart 05qZ) stated that the fecundity of an 8.9 kg yelloweye
rockf i sh was 2,700,000.G. Incubation Period
Rosenthal (1983) stated that breeding takes place in winter months
and that young are released in June, July, and August.
VI. MOVEMENTS ASSOCIATED hlITH LIFE FUNCTIONS
The average length of ye'lloweye rockfish in the commercial catch
increases with depth (Rosenthal et. al. 1982). This ind'icates that
yel lon.y. move to progressively. deeper ar-e-as as they. gfow (ibid. ):
iel 'l owtii I and dus'ky -rockf i sh -(Sebastes
_Il_qvi dus and S. ci l-!-atus.) near
Auke Bay, Al aska, have been'EF5ffid-E- move iilto -ilvices and
shelterei areas in November-April, possjbly in response to a dr.op in
water temperature (Carlson anO Barr 1977). Rosenthal et al. (198?)
found that canary and rosethorn rockfish (Sebastes pinniger and l.
hel vomacul atus ) i ncreased i n rel ati ve abundance in the wj nter
commerffi-ltori zontal l ong1 i ne catch, dS compared to surnmer. He
speculated that this may b-e due to a shift to a more bottom-dwe1ling
eiistence by these normally pelagic spec'ies. In contrast, the relative
abundance of yelloweye rockfish in the commercial catch decreased in
the winter.
VII. NATURAL FACTORS INFLUENCING POPULATIONSA. Naturalyel'loweye larvae and young are undoubtedly eaten by other rock-
fish. -Small yelloweye- rockfish have been found in the stomachs of'larger yel lowbyes (Rbsenthal et al . 1982).
B. Human-rel atedA summary of possible impacts from human-related activities
i ncl udes the fol 1 owi ng :
" Alteration of preferred water
oxygen, and chemical comPosi t'ion
temperatures, pH, dissolved
o Introduction of water soluble substances
" Increase in suspended organic or mineral materialo Reduction in food suPPlYo Human harvest
" Se'ismi c shock waves
(See the Impacts of Land and Water Use volume in this serjes for
additional jnformation regarding impacts.)
VI I I. LEGAL STATUS
Stocks of ye'lloweye rockfish within the 3-mi limit are regu'lated by the
Alaska Department of Fjsh and Game. More details of management status
can be found in the Human Use section of this report.
374
IX. LIMITATIONS OF INFORMATION
Very little life history information on nearshore rockfish in Alaska is
avai I abl e.
REFERENCES
Carlson, H.R., and L. Barr. 1977. Seasonal changes in spatia'l d'istribution
and activity of two species of Pacific rockfishes, Sebastes flavidus
and S. Ciliitus, in Lynn Canal , Southeastern Alaska.--E-af-Ti5F. Tev.zg:zT-zC-
Carlson, H.R., and R.R. Straty. 1981. Habitat and nursery grounds of
Pacific rockfjsh, Sebastes spp., in rocky coastal areas of Southeastern
Alaska. Mar. Fishl-M43:13-19.
Gotshall, D.hJ. 1981. Pacific coast inshore fishes. Sea Challengers. Los
Osos, California. 96 pp. Cited jn Rosenthal et al . L982.
Hart, J.L. 1942. News item. Red snapper fecundity. Fish. Res. Bd. Can.
Pac. Prog. Rept. 52. 18 pp. Cited in Hart 1973.
. 1973. Pacific fishes of canada. Fish. Res. Bd. can. Bull. 180.---m'pp.
Helvey, M. L982. First observations of courtship
genus !eE$et. Copeia 1982 (4)2763-770.
Moryison, R. 1982a. Groundfish investigations in the Cook Inlet, Prince
ylilliam Sound portions of Region II. Prepared for NMFS, Seattle, t,JA.
Draft copy. 47 pp,
. 1982b. Trip report. 0uter djstrict rockfish survey. June 1-10,
-tg82.
Lower Cook I nl et Data Rept. 82-6 . ADF&G, Di v. Commer. Fi sh. 'Homer. July 1982, 20 pp.
. 1984. Personal communication. Central
--B'lologist, ADF&G, Div. Commer. Fish., Homer.
Region Groundfish
Rosenthal, R.J. 1983. Shallow water fish assemblages in the northeastern
Gulf of Alaska: habitat evaluation, species composition, abundance,
spatia'l djstribution and trophic interaction. Environmental assessment
of the Alaskan continental shelf. Final reports of principal investi-gators. Vol . 17: Biological studies. USDC: NOM, USDI, Minerals
Management, 0CSEAP. February 1983.
Rosenthal, R.J., L.J. Field, and 0.0. Myer. 1981. Survey of nearshore
bottomfish in the outside waters of Southeasten Alaska. Prepared for
ADF&G, Div. Conmer. Fish. March 1981. 85 pp. + appendices.
behavior in rockfish,
375
Rosenthal , R.J., L. Ha'ldorson, L.J. Field, V.M. 0'Connel , M.G. LaRiviere'
J. Underwood, and M.C. Murphy. t982. Inshore and sha]low offshore
bottomfish resources 'in the southeastern Gulf of Alaska. Prepared for
ADF&G, Div. Commer. Fish. December 1982. 166 pp.
376
Shellfish
Ilungeness Crab Life History and Habitat Requirements
Soutlnrest and Southcentral Alasha
-#ii
Conmon Names: Dungeness crab, market crab, common edible crab,
Pacific edib'le crab, commercial crab, dungeoness crab
Scientific Name: Cancer magister Dana
fiiitiii:i ':::::
Map 1. Range of Dungeness crab (ADF&G 1978; Kess'ler' pers. comm.;
0tto, pers . conrm. )
I.
II.
NAME
A.
B.
RANGEA. Worldwide
Dungeness crabs occur in
Pacific along the westernlimit at Unalaska Island
(ADF&G 1e78).
shallow nearshore waters of the North
North American coast' with the western
and the southern limit at Monterey Bay
Y
i" o J .ttpJbo
379
B. Statewide
Cancer mag'ister range from Dixon Entrance to Unalaska Island.
c. ReglonaT-Dlffifbution Summary
To-supplement the distribution information presented in the text,
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale,
bui some are at 1:1,000,000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition'
a set of colored 1:1,000,000-scale index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.
Dungeness crabs inhabit estuaries and the open ocean area from the
intertidal zone to depths greater than 50 fathoms. The.greatest
abundance is found on'mud oi sand substrates (Hoopes 1973).
1. Southwest. Concentrations occur in the Kodiak and South
FAn]nille areas. (For more deta'iled narrative information,
see volume 1 of the Alaska Habjtat Management Guide for the
Southwest Region. )2. Southcentral. Concentrat'ions occur in the Prince William
ffiI--Lower Cook Inlet areas. (For more detailed
narrative'information, see volume 2 of the Alaska Habitat
Management Guide for the Southcentral Region.)
III. PHYSICAL HABITAT REQUIREMENTSA. Water Qual i ty
Laboratory itudies define the optimum range of temperature and
salinity for larvae to be 10.0 to 13.9oC and 25 to 30 parts per
thousand (0/00) , respectively (Reed 1969). Water temperatures
appear to influence crab distribution; Dungeness crabs are scarce
in warm brack'ish water (McKay 1942). Changes jn sa'linity
influence shallow water distribution. Large Dungeness crabs have
been found to retreat from areas of reduced salinity (Cleaver
1e4e).B. Water Quantity1. Larvae. Larvae are p1 anktonic and associ ated wi th the
ne-ffih'ore location of adult females in spring (Mayer 1972\.
2. Postlarvae and juvenile. Postlarvals crabs are most abundant
ffie areas shallower than five fathoms.
Juvenile crabs may seek refuge from predators by hiding among
seaweeds (Hoopes 1973).
Adul t. Adul ts i nhabi t depths of
T00-Tathoms (Hitz and Rathien 1965;
The preferred substrate is a sand or
adult Dungeness crabs may be found
substrate (ADF&G 1978).
3.from less than 1 to
Ni ppes , pers. comm. ) .
sand-mud bottom, though
on almost any bottom
380
IV. NUTRITIONAL REQUIREMENTSA. Preferred Foods1. Juveniles. The diet of juveni'les is similar to that of
aduTls, and is comprised of crustaceans and molluscs.
Z. Adults. The diet of adults consists of crustaceans (shrimp,
crTfil-barnacl es , amphi pods , and i sopods ) cl ams , polychaetes ,
and iuvenile crabs (McKay L942, Hoopes 1973).
B. Feeding Behavior
Dungen6ss crabs are carnivores. Laboratory- experiments show that
treshneis of prey is important in inducing-feeding response (McKay
1943). Aquaria-kept crabs have been noted to captu_re and devour
sticklebacks with remarkable speed. Consistently, fish prey were
held by the chelae and eaten head first. Dungeness crabs have
also bien observed to chip away the edges of oysters and bivalves
to feed. Crabs were observed Crushing barnacles with their chelae
(ibid.). Small bristles on the claws are extreme'ly sensitive to
the touch of prey. Dungeness crabs have been known to hunt prey
items by probing with partially open claws (Butler 1954).
V. REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat
Adults move to shallow water for mating.
B. Reproducti ve Seasonal 'itY
Nai'ing occurs duri ng the spri ng mo1 ! peri od, whi ch i s as 'l ate as
Augusl in certain aieas (Rogeriet a1..1980; Nippes' pers. conrn.).
C. Reproductive Behavior
Oui^ing mating, the male grasps the female with chelae, then holds
her b6neath himself so that the sterna are in contact. The male
tries to restrain the female during the molt but allows her to
return to an upright position (Cleaver 1949, Butler 1960' Snow and
Nielsen 1966). Mating occurs withjn one hour and 30 minutes after
the female molts. The postmating embrace has been observed to
last two days (Snow and Nielsen 1966). The oviduct is closed
after mating by a secretion that hardens in sea water, and
spermatazoa -are sealed in the oviduct, remaining viable for
several months to ferti'lize eggs upon extrusion (McKay 1942).
D. Age at Sexual MaturitY
T[ere is little informat'ion available regarding age at maturity
for Dunqeness crab in Alaska. Though he does not specify the
location, Hoopes (1973) states that sexual maturity 'is attained at
about two years for males and three years for females. This
corresponds to a carapace width greater than 110 mm for males and
100 mm'for females for crabs from Queen Charlotte Is'lands (Butler
1960). Both sexes mature at the eleventh or twelfth post'larval
molt (Butler 1961). In British Columbia, sexua'l activity is- not
appreciable until a crab obtains a carapace width of 140 mm
(birtter 1960). Molting may occur annually in mature adults (Mayer
rs72).
381
E. Fecundity
Fecundi ty i s re1ated to the
carry more eggs than smaller
mass has been documented to
speculation that a female may
a life t'ime (McKay L942).F. Frequency of Breeding
size of the female. Larger females
females (Hoopes 1973). A sing'le egg
contain 1,500,000 eggs. There is
spawn 3,000,000 to 5,000'000 eggs in
can mate only after the mo'lt duringMa'les are polygamous . Femal es
the spring (Hoopes 1973).G. Incubation/Emergence
Females carry viable sperm in oviducts throughout the sumner.
Eggs pass through the oviduct, are ferti I ized, and then are
ciirjed under thd females abdomen during the fal1 months (ibid.).
Femal es can ferti I i ze mul ti p1 e cl utches wi th stored sperm
(Hilsinger, pers. conrm. ). In British Co'lumbia, €99 bearing occurs
from October through June (McKay 1942). Eggs are carried by the
female from 7 to 10 months (Hoopes 1973). In the Oregon area'
larvae emerge from egg masses from December to April (Reed 1969).
Larvae progress through five zoeal stages by a se-ries of molts,
with eaih faking three to four months. There is only one megalops
stage resembling juvenile crab (Poole 1966). Jh. mega'lops stage
setiles out of lfre water column as a postlarval or iuvenile crab
after a larval period of LzB to 158 days (ibid.). In Kodiak,
larvae spend up to three months in p'lankton (AEIDC 1975), and_the
peak larval release occurs in spring or ear'ly sutnmer (Kendall. et
it. 1980). Juvenile crab grow rapidly, molting six times within
the first year. The carapace witlth (Ct,J) at the end of the first
year is about 25 mm, and after the second year CW js about 102 mm
( Hoopes 1973) . Mo'l ti ng pepi ods I ast f rom one to two days . Tl,.
growth rate for both sexes is similar until sexual maturity is
ittained, after which males gro$, faster (ibid.).
VI. MOVEMENTS ASSOCIATED t^lITH LIFE FUNCTIONSA. Larvae
Eggs are not plankton'ic but are carried by the female. The eggs
hitch into free-swimming larvae during the spring after having
been carried by the female for 7-10 months (Hoopes 1973). Larvae
are thus planktonic and are found in nearshore areas in spring.
Ear'ly distribution of larvae is therefore dependent YPon thq
distiibutjon of adult females. However, larvae become dispersed
with t'ime.
Larvae in inshore areas are mostly found in the upper portion of
the water column during the day (10 to 30 m), dispersing to depths
of 50 to 90 m at night (Kendall et al. 1980).
B. Juveni I es
Small crabs have been associated with strands of eelgrass or
masses of detached algae, which are believed to provide protection
(Butler 1956). Young crabs have been found buried in intertidal
iand in February andlurjng the spring months (McKay L942).
C. Adults
Adult crabs migrate offshore during the winter months and return
to nearshore witers in the ear'ly spring and summer months (McKay
1942, 1943, Cleaver 1949, Butler 1951).
382
VII. FACTORS INFLUENCING POPULATIONSA. Natural
Larvae are preyed upon by salmon and herring (Heg and Van Hyning
1951, McKay' li42). Cannibalism is common among crabs in life
stages bey6nd the megalops stage (l'laldron 1958). Juvenile crabs
have been- preyed upoi by wo]f -eel s (Ana!"fhicthys ggil I atus) and
paci fi J-r'ufi uui ( ii ppoqt-ossus steno].pt Xnf ltsTfllngcod
(0ohiodon el onqatGTifrTkffihl5fa;fes spp. ) , wol f eel s, and
iffi-naTiSFme voracious pEd-ators upon adults (waldron
1958).B. Human-relatedA summary of possible impacts from human-related activities
i ncl udes the fol'lowi ng:o Alteration of preferred water temperatures, PH, dissolved
oxygen, and chemical compositiono Alteration of preferred substrate
" Alteration of intertidal areaso Increase in suspended organic or mineral materialo Reduction in food suPPlYo Reduction in protective- cover (e.g., seaweed beds)o 0bstruction of m'igration routes
" Shock waves in aquatic environmento Human harvest ( i ricl udi ng handl i ng of non'l egal crabs )
(See the Impacts of Land and Water Use volume of this series for
additional impacts information. )
VI I I. LEGAL STATUS
The Dungeness crab is managed by the Alaska Department of Fish and
Game.
RE FERENCES
ADF&G 1978. Al aska' s fi sheries atl as. Vol .
K.J. Delaney, comps.]. 43 pp. + maps.
2 [R. F. Mclean and
I iving. Unjv. Alaska, Anchorage.
tagging experiment jn the Graham
Can. Pac. Preg. Rept.89:84-87.
. 1954. Food of the commerc'ial crab in the Queen Charlotte Islands
-g-ion.
Fish. Res. Bd. Can. Pac. Prog. Rept. 99:3-5.
. 1956.The distribution and abundance of early post larvae
British Columbia Cornmercial crab. Fish. Res. Bd. Can.stages of the
Pac. Prog. Rept. I07:22'23.
. 1960. MaturitY and breeding of
- gggi:t* Dana. J. Fish. Res. Bd. Can.
AEIDC. 1975. Kadyak: a background for
Butler, T.H. 1951. The 1949 and 1950
Island crab fishery. Fish. Res. Bd.
the Pacific edible
17(5):641-646.
383
crab, Cancer
. 1961. Growth and age determination of the Pacific edible crab,.@ magister Dana. J. Fish. Res. Bd. Can. 1B(5):873-891.
Cleaver, F.L. 1949. Prel iminary results of the coastal crab (Cancer
madister) investigation. Was[. Dept. Fish. Biol . Rept. 49A:47-gf-
Heg, R., and J. Van Hyning. 1951. Food of the chinook and silver salmon
taken off the 0regon coast. Brief 3(2):32-40.
Hi'lsingerr J.R. 1984. Personal communication. Management coordinator,
Central Region. ADF&G, Div. Commer. Fish., Anchorage.
Hitz, C.R., and W.F. Rathien. 1965. Bottom trawling surveys of the
northeastern Gulf of Alaska. Sunrner and Fall of 1961 and Spring of
1962. Corrner. Fish. Rev. 27(9):1-15.
Hoopes, D.T. 1973. Alaska's fishery resources: the Dungeness crab. NMFS.
Fishery Facts No. 6. Seattle. 14 pp.
Kendall, A.W., Jr., J.R. Dunn, R.J. [,lolotira, Jr., J.H. Bowerman, Jr.' D.B.
Dey, A.C. Matarese, and J.E. Munk. 1980. Zooplankton, includ!!9
icthyoplankton and decopod larvae of the Kodiak shelf. NOAA' NMFS,
Nt.lAFC.' 0CSEAP ann. rept. RU-551. Cited in Rogers et al. 1980.
Kessler, R. 1984. Persona'l comrnunication. Shellfish Biologist, NOAA
NMFS, NWAFC Kodiak Investigation-Research, KodiakrAK.
Mayer, D.L. 1972. Synopsjs of biological data on the Dungeness crab.Cangqr- mqgister (Dana 1852) with emphasis on the Gulf of Alaska. Section 14.
PttfUST-312 in D.H. Rosenburg, ed. A review of the oceanography and
renewable reso-urces of the Northern Gu'lf of Alaska. Institute of
Marine Science, Fa'i rbanks.
McKay, D.C. 1942. The Pacific edible crab,Cancer magister. Fish. Res.
Bd. Can. Bull 62:32
. 1943. The behavior of the Pacific edible crab, Cancer magister
-oana.
J. Comp. Psych. 36 (3):255-258.
McMynn, R.G. 1951. The crab fishery off Graham Island, British Columbia,
to 1948. F'ish. Res. Bd. Can. Bul l. 97:7-2I.
Nippes, W. 1983. Personal communication. Area Shellfish Mgt. Eiologist,
ADF&G, Div. Commer. Fish., Kodiak.
0tto, R.S. 1984. Personal communication. Laboratory Director, N0AA, NMFS,
NWAFC, Kodiak, AK.
384
Poole, R.L. 1966. A description of 'laboratory reared zoea of Cancer
magister Dana and megalopae taken under natural conditions (DecoFoZa'
ETEEhIura). Crustaceana 11( t) :e:-gZ.
Reed, P.H. 1969. Culture methods and effects of temperature a.nd salinity
on survival and growth of Dungeness crab (Cancer magjster) larvae in
the I aboratory. i . Fi sh. Res . -gd. can . 26(2)-:389-39t-
Rogers, B.J., M.W. Wangerin, K.J. Garrison, and D.E. Rogers. 1980. Epipel-
agic meroplankton, juvenile fish and forage fish: distribution and
relative abundance in coastal waters near Yakutat. RU-603. Pages
1-106 in Environmental assessment of the Alaskan continental shelf.
Final reports of principal investigators. Vol . L7: Biological studies.
USDC: NOAA, USDI: MMS. 1983.
Snow, C.D., and J.R. Nielson. 1966. Premating and mating behavior of the
Dungeness crab (Cancer magister Dana). J. Fish. Res. Bd. Can.
23(e):1319-1323.
Waldron, K.D. 1958. The fishery and bio'logy of the Dungeness crab (Cancer
magister Dana) in region waters. Fish. Comm., 0regon. Contr. 24:I-43.
385
I.
Ifing Crab Life History and Habitat Requirements
Soutftwest and Southcentral Alasha
Map 1. Range of king crab (ADF&G 1978)
NAMEA. Conrnon Names: King crab, golden king crab, brown king crab, blue
crab, red king crabB. Scientific Names: Paralithodes camtschatica (red king crab)
FaElTtFoAei F.|TTyLT15 l-b'l-rd t<t ns ciab )
ffin-oAes aquisp-lnET6'rown or goioen king crab)
EXTENT TO t^lHICH SPECIES REPRESENTS GROUP
Red king crab (Paralithodes camtschatica) is the most abundant species.
Blue king crao TPf''FaTitffiiEi is not as abundant but morpho-
1 ogi cal ly i s simfTaFTo-Ted--Ti ng crab-;
Golden or brown king crabs inhabit deeper water (greater than 100boroen or Drown Klng crabs 'tnhablt deeper water (greater than 100
fathoms) than the other two species, and their relafive abundance is
II.
Ji::i:ii!ir{:::::::::::
:::il:::::::iti
iiiiiiiiiiiiiii
:::iK
Hii
diii:::::::
::il
:::::\t \ii::ii*rd:::::::::::i\t
:::::::::::::::: T
;:::i:iii:iti:itii
unknown.
387
Because of the emphasis upon red king crab and the resulting availabil-ity of information on its abundance, the following summary emphasizes
the red king crab life history.
III. RANGEA. hjorldwide
Red king crab is not only the most abundant of the three cormer-cial species; it is the most widespread. In Asian waters, red
king crabs are found from the Sea of Japan northward into the Seaof 0khotsk and along the shores of the Kamchatka Peninsula. The
northern limit on the Asian coast is Cape Olyutorsky. 0n the west
coast of North America, distribution extends northward from
Vancouver Island, British Columbia, to Norton Sound in the Bering
Sea. The distribution of blue king crab extends along the North
Pacific rim from the Sea of Japan to Southeast Alaska, including
the Bering and Chuckchi seas. Brown king crab appears least
abundant in Alaskan waters, inhabiting deeper areas along the
continental slopes of the North Pacific 0cean from the Sea of
Japan to Vancouver Island, including the Bering Sea south to
Vancouver, and the 0khotsk Sea south to Japan (NPFMC 1980;Otto,
pers. comm. ).B. Statewide
See Worldwide.C. Regional Distribution Summary
To supplement the distribution information presented in the text,
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale,
but some are at 1:1,000,000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition,
a set of colored 1:1,000,000-scale index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.
1. Southwest. Major concentrations of red king crab are located
nda-F--K6cfiak Island, the south Alaska Peninsula, and the
Aleutjan Islands and in the southeastern Bering Sea. Brown
king crab is found in the same area described above (ibid.).
Isolated populations of blue king crab occur in the Kodiak
and Bering Sea area. (For more detailed narrative inform-
at'ion, see volume 1 of the Alaska Habitat Management Guide
for the Southwest Region. )2. Southcentral. Major concentrations of red king crab are
locateA-TnTower Cook Inlet and Prince Wil I iam Sound. Brown
king crab is found in the same area. Isolated populations of
blue king crab occur in the Prince William Sound area. (For
more detailed narrative information, see volume 2 of the
Alaska Habitat Management Guide for the Southcentral Region. )
388
IV.PHYSICAL HABITAT REQUIREMENTSA. Water Qual ity
King crabs are unable to withstand wide variation in salinity and
are adapted to cold water (Eldridge 1972). Distribution of the
red king crab in the southeastern Bering Sea is dependent upon
bottom temperatures. Water temperatures where this species occurs
range from -1 to 10"C (Bartlett 1976). Summering adu'lt male and
female king crabs inhabjt a temperature range of from 0 to 5.5oC.
Maximum abundance of females occurs at a temperature range of from
3 to 5"C, and maximum abundance of males at 1.5'C (Stinson 1975).
After the fifth molt, juvenile crabs inhabit rock crevices, k.]p
patches, or other proiective niches (Jewett and Powell 1981).
i,later temperatures influence the frequency of molting. lglvae can
molt successful'ly in water temperatures between 2 and 12oC, but a
decrease in temperature from 10 to 5'C delays the development time
(Kurata 1959, 1960a, 1960b, 1961).B. Water Quantity
Larvae are pelaqic. Females and small males are most abundant at
intermediat6 Oeittrs (Eldridge I972). Juveniles are most abundant
in inshore waters and re'latively shal low waters less than
75 fathoms, and they have been found to depths of 58 fathoms
(NPFMC 1980). The reO t<'ing crab in Cook Inlet occurs in depths up
to 200 fathoms. Young red king crabs 'less than one year 9! age
and 3 to 12 mm in carapace length exist mainly as solitary
individuals among rock crevices, kelp patches, and other protected
areas where they- settle as larvae (Powell and Nickerson 1965a).
Crabs 9 to 19 mm in carapace length are common 0n
barnacle-encrusted dock pi'lings in the Kodiak area. Adult red
crabs appear to prefer a mud-or sandy substrate (Eldridge I972)
and havd been fouhO at depths of 200 fathoms (NPFMC 1980). Golden
king crabs in Prince Wil I iam Sound have been found in the
deep-water trench running from Hinchinbrook Entrance in the
westward arc to Knight Island Passage (ADF&G 1978).
NUTRITIONAL REQUIREMENTSA. Preferred Foods1. Larvae. Larvae feed primarily on diatoms.
2. ffifiles. The preferred diet of postlarval crabs on the
wilTamchatka 'shelf were hydroids (Lafoeina maxima)
(Tsalkina 1969). In lower cook Inlet, postlarval crabs
ingested detrital materials, diatoms, Bryozoa, harpacticoid
copepods, ostracods, and sediment (Feder and Jewett 1981).
3. AOirlts. The diet differs according to the geographic region.
eFE5ffeed on dominant benthic forms (Kun and Mikulich 1954,
Kulichkova 1955). In the southeastern Bering Sea, a number
of food habit studies have been performed. Dominant food
items have been cockles (Cl inocardium cil iatum), a snail(solariella sp. ), a clam lT-uElana =osTal-brittle stars
(mpnimo.e),' a polychaete @ sp. ), and snow
V.
389
B.
crab (Chionoecetes sp.) (Feder and Jewett 1980). Tarverdieva(I976)-found-ffi4 main foods to be polychaete worms,
sanddol lars (Echinarachnius parma), gastropods of the
famil ies TrochltEE--and-laTJcid-ae, and pelecypods (Yoldia,
Nuculana, Nucu'la, Cyc'locardia). Cunningham (1969) deterffied
6FiTf'le stars J0pI-Tura sarsi ), basketstars (Gorgoncephalus
sp.), sea urchin@ tp. ano Eh'Tn--iTE?h'n'iIi3
parma) to be mainffing in imFoffi
fr6TT[sks (Nuculana radiata, Clinocarduim californiense,
chl amys sp. )-l snaiTi (so-Ta rlEt r a TF.-ffi i njtae-) @--
cET-iI(-cran:Hyas coarctatus al utacesus, Erimacrys
isenbecki i , afrd-pagarus -TpJ; and E'i'dTTEE's (AmFfiIFodfidffi ano HenadTg0t) determined major food items to
be molluscs (Oivalves), echinoderms, and decapod crustaceans.
The diets of the two sexes were not found to be significantlydifferent. King crabs in the Bering Sea must often compete
for food with other bottom-feeding organisms (snow crabs, sea
stars, Pacific cod, yel lowfin sole, Alaska p'laice rock sole,
and flathead sole) (Feder and Jewett 1981, Takeuchi 1959).
The diet of red king crabs in the Gulf of Alaska (Kodiak and
Afognak islands) is diverse. Prey in Izhut Bay at Afognak
Island were fishes, probably cape'lin (Mallotus villosus),
which was an unusual occurience (Otto,[ers. comrnFln
Kiliuda Bay at Kodiak Island, pr€J consisted of clams, and on
the outer Kodiak shelf, crabs, clams, crustaceans, and fishes
were important; crabs from shallow bays at Kodiak Island
preyed upon clams (Protothaca stamina, Macoma sp.), cockles
(Cl inocardium sp. ),_irE acorn TTrnETies-(BaTanus crenatus).Tffire significant differences in tFe-fr-oo-qu'anT-itv
consumed among sampling areas, time periods, depths, and crab
sizes (Feder and Jewett 1981). Predation upon sea stars
(Pycnopodia hilianthoides and Evasterias try:lg]ii) has beeno5ffii ano-deemEd-TmportantFiFETiTlTy w[en crabs a re
foraging in shallow waters in late spring and summer (Feder
and Jewett 1981, Powell 1979).
Lower Cook Inlet red king crabs also manifested regional
differences in food hab'its. Crabs in Kachemak Bay fed on
clams (Spisula polynyma), whereas crabs from Kamishak ate
mostly 6aFnacTes.--DiEFs of postlarval king crabs in CookInlet contained detrital material, diatoms, bryozoa,
harpacticoid copepods, ostracods, and sediment (Feder et al.
1980 ) .
Feeding Behavior
The king crab is omnivorous during the juvenile and adult phases
of its life (Eldridge 1972).
390
VI. REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat
The preferred habitat for reproduction is shallow water of less
than 50 fathoms and offshore ocean banks (ibid.). Molting and
mating have been observed in 10 to 90 ft of water in areas where
kelp is common (Jewett and Powell 1981).In the Kodiak area, breeding king crabs were concentrated at
depths of 3 to 8 fathoms within the lower zone of kelp and
boulders. In this area, breeding crabs appeared to prefer kelp
areas where Alaria, Costaria, and Laminaria were common. Rocks
and ke'lp pro6a'6[provTffii-lrotectiofr-J6-The soft female during
edysis (molt) and the subsequent mating (Powe'll and Nickerson
1965b).B. Reproductive Seasonal ity
Females molt and mate from February through May. Males molt
earlier than females, and young adults of both sexes molt earlier
than o'ld adults. Mature males tend to molt biennially or eventriennially. Males molt prior to arriving on the mating grounds
and therefore arrive in hard-shell condition (Eldridge 1972).
Around Kodiak Island, female crabs begin to move toward the mating
grounds in November. Young females and older males reach the
spawn'ing grounds first (Powell, pers. comm.). Powell and
Nickerson (1965b) found that crabs in the Kodiak area molted and
mated from mid February through the third week of Apri1. The
female migration to the spawning grounds begins about the same
time as that for males. In Cook Inlet, timing of the mating
period differs slightly between bays. In Kachemak Bay, king crabs
begin spawning in February, with a peak in Apri1. Kamishak king
crabs may spawn s1i9ht1y later (ADF&G 1978).C. Reproducti ve Behav'iorAfter the larvae hatch, females molt and then mate (McMu11en
1969). Males select females according to size and behavior.
Female crabs can mate on'ly in the soft-shell condition (Jewett and
Powell 1981), and those not mating after molting will not extrude
eggs (ADF&G 1978). For mating to be successful among females of
each congregation, an adequate number of capable males must be
present in the vicinity during the brief receptive period
following female ecdysis (molt). Mating will be unsuccessful for
females waiting for a partner longer than five days after molting
(Powell et al . 1974).
Male king crabs will grasp females at the base of both claws while
facing them, "embracing" for up to 16 days. After the female
molts, the male crab releases her old shell and reclasps the
female (Jewetr and Powell 1981). Small males probably produce
fewer spermatophores than large males, possibly resulting in a
diminished ability to fertilize the greater egg masses of large
females. Copulation and deposition of sperm on the female's
gonopores can occur only after the female mol ts and before
ovulation (Powell and Nickerson 1965b).
391
D. Age at Sexual Maturity
There is a wjde enough variation in size at maturity to suggestthat age and growth rate are also important factors in reaching
sexual maturity (Hilsinger 1983). Age is difficult to assess in
king crabs. In the Kodiak area, the carapace length of mature
females ranges from about 93 mm to I20 mm. About 50% of the
females are mature at about 100 mm (Powell et al. L972). In the
southeastern Bering Sea, sexual maturity for females has been
attained between a minimum carapace length of 86 to I0? mm
(Wal1ace et al. 1949). Females appear to breed shortly after
attaining sexual maturity (Haynes and Lehman 1969). In female
crabs, molting is correlated with reproduction. Mo'lting occursjust before mating each year. Females after five years are
probab'ly annual molters (Powell and Nickerson 1965b).
Male king crabs as small as 86 mm carapace length have been found
capable of mating. They attain sexual maturity at a smaller size
and younger age than do females. It is uncertain, however,
whether the small mature males are functioning adequately as broodstock. In captivity, Gulf of Alaska males were found to reach 50%
maturity at 86 mm (Powell et al . I97?).
After attaining sexual maturity, possibly in the 4th and 5th year,
adults molt annually for several years, and then some individuals
begin to skip molt at approximately seven years of age (Powell and
Nickerson 1965b). Males that molt during the mating season may
not mate after molt'ing because molting may interfere with mating.
Molting areas for males may be distant from the mating grounds.
Males who skip molt two consecutive years may die after the next
breeding period (Haynes and Lehman 1969).
Male king crabs grow larger than female king crabs. Male king
crabs may grow as large as 24 lb in 15 years, whereas a female
crab of the same age would be only 10 lb (NPFMC 1980).
Fecundi ty
The number of eggs produced by the female increases with carapacesize. In Kodiak waters, small females may carry 50,000 to 100,000
€9gs, with large females carrying 400,000 eggs (Eldridge 1972).
In Cook Inlet, fecundity has been reported to range from 25,000 to
390,000 eggs (Haynes 1968). The low numbers of eggs carried by
some females could be attributed to partial fertilization of large
females by smaller males (ibid.). It could also be related to the
food supply and age of the individual female because males very
rarely mate with females larger than themselves (Hilsinger, pers.
comm. ).
Frequency of Breeding
Females apparently mate with only one male (Eldridge 1972). The
mating ability of males varies with their size and is affected by
the time of year they molt (ibid.). Males of varying sizes and
shel I ages have been shown to mate successful 1y (producing
fertilized clutches of greater than 75%) with four to nine females
(Powell et al. 1974). Captive males are polygamous and have been
documented to mate with L4 females during one season (Jewett and
E.
F.
392
Powel I 1981 ) . Femal e mo1 ti ng i s c1 osely associated wi th
reproduction, with one molt occurring annually prior to extrusion
of the eggs (Gray and Powel I 1966 ) . Mal es general 1y mol t
annual ]y, -6ut males older than eight years may shed their
exoskeletons once every two or three years (Manen and Curl 1981).
These skip-mo1 t males may play an important role in the
reproductive success of stocks, compared to newly molted males
whose mati ng abi 1 i ty i s hampered by the process of mo1 ti ng
( ibid. ).
I ncubati onlEmergence
Female k'ing crabs carry their eggs externally for about 11 months.
Eggs develop into prezoea within five months of fertilization and
remain in this state while carried by the female. Just before
mating, prezoea hatch and molt into zoea larvae, which assume a
pelagic existence (Eldri dge 1972). Egg development may be slowed
by colder temperatures. Eggs hatch during a three-month period
from March through June. Peak hatch periods and larval abundance
in the eastern Bering Sea occur from early May through mid Ju1y.
Larvae are concentrated along the north Aleutian Shelf from Unimak
Island into Bristol Bay (Manen and Curl 1981). The time interval
between molts progressively increases from a minimum of three
weeks for early postlarval iuveniles to a maximum of three years
f or adu I t ma I es ( t{prNc 1980 ) .
During the first year, iuvenile king crabs
the following year 8 molts (Manen and Curl
VII. MOVEMENTS ASSOCIATED t,'lITH LIFE FUNCTIONSA. Larvae
Released larvae are pelagic, with some swimming ability. Studies
indicate that ocean currents distribute larvae into nursery areas
that are shallow and close to shore. In Cook Inlet, larvae are
present in the plankton from mid February to late June. Larvae
remain p'lanktonic about 30 to 40 days. After the fifth molt,
larvae become benthic. In Cook Inlet, the demersal -benthic
settling generally occurs from mid April to 1ale August but is
heaviesi dur"ing July through August (ADF&G 1978). The iuvenile
form occurs after the sixth molt.B. Juveni I es
First-year juven'i1es assume a solitary benthic exiStence in
relatively shallow water and in the Gulf of Alaska are abundant in
waters ciose to shore (Eldridge I972). Large concentrations of
juveniles have been found at depths of 29 fathoms (Powell and
Reynol ds 1969).
During their second year, iuveniles aggregate into large groups
called "pods." Pods are maintained until the crabs reach sexual
maturity. Upon reaching sexual maturity, crabs Segregate by sex
and sile. Pods are bel ieved to provide protection against
predators. Pods are found year-round and are compriSed of both
males and females of similar size. Pods appear to disband when
G.
undergo 11 molts and in
1e81 ).
393
crabs feed or change location. Subadult and adult aggregationsare more scattered and circular compared to pods (Powell and
Nickerson 1965a ).C. Adul t
Adults inhabit deeper water than juveniles (Eldridge 1972). Males
segregate from females except during the mating season (ibid.).
Adult king crabs also segregate by size within sex-segregated
groups (NPFMC 1980). King crabs follow distinct annual migra-tional patterns associated with the mating season, moving to
shallow water less than 50 fathoms along the shoreline and onto
offshore ocean banks. Young adults precede o'ld adults, and males
migrate before females (Powell and Nickerson 1965b). Upon arrivalat the spawning grounds, females may emit a pheromone thatattracts males (NPFMC 1980). A molting and mating/spawning
migration occurs in the spring, and a feeding migration offshore
occurs in the fall (Marukawa 1933). The migration of red king
crabs to shallow water in the Kodiak area begins in January and
continues through April (NPFMC 1980). Migration timing in the
eastern Bering Sea is believed to be similar but later than thatof the Kodiak stock (ADNR/USFWS 1983). In Cook Inlet, red king
crabs undergo seasonal mi grations consi sti ng of an i nshore
movement in spring and summer and an offshore movement to deeper
waters in fall/winter. In Kachemak Bay, the inshore spawning
migration begins jn late December and extends through May. Peak
movement is in early March. 0ffshclre movement in the arear whichis termed the feeding migration, begins in September and extends
through November. This movement is a slow foraging process rather
than a direct journey into deeper water (ADF&G 1978).
VIII. FACTORS INFLUENCING POPULATIONSA. Natural1. Predation. A high mortality of larvae occurs from predation6y-ilanftivores. Sculpins, cod, and halibut have been
reported to prey on juvenile king crabs (Eldridge I972).
Horsehair crabs (Erimacrus isenbeckii) have been observed to
prey upon juveniTe-TTng:Fa6F-wh'en tfre pod was di sbandedafter being .disturbed by divers. Sculpins (Hemilepidotus
hemi lepi{orlqs ) al so prey upon juveni les (Powel I and-NTckerson
2.
Adult crabs are particular'ly susceptible to predation when in
the soft-shelled stage. Halibut have been reported to prey
upon soft-shelled adult crabs (Eldridge 1972). Sea otters
and bearded seals have also been observed predators upon
adult crabs (Feder and Jewett 1981).
Disease and parasites. Adult crabs are affected by diseases
or parasites. Instances of the following afflictions occur:" Rust disease: infestation of exoskeleton by chitin-
destroyi ng bacteria; affects P. camtschatica and P.
platypus in the North Pacific (S-inderrnann T-9JT'J-
394
Rhizocephalen: infects P. platypus, P. camtschatica, andL. aquispina (This paralTfl?-narnacTellTl-inhibit
moltlng, cause "parasitic castrationr" and retard gonad
development INMFS 1983]. )
Nemertean worm (Carcinomertes sp. ) infestations have
been found jn k-ing- cr;6' egg clutches and may be
responsible for egg mortality. Carcinomertes has been
documented in Kachemak Bay (Cook Inlet) king crabs.
infestation has coincided with reduced egg c'lutches and
high egg mortality (Merritt, pers. comm.; NMFS 1983).
Acanthocephalan, a parasitic pseudocoelonate found in
connective tissue of the midgut of the king crab, causes
damage to the intestinal wall. This organism has been
documented in king crabs from Cook Inlet and Bristol Bay
(NMFS 1e83).B. Human-rel atedA surnmary of possible impacts from human-related activities
includes the fol lowing:o Alteration of preferred water temperatures, pH, dissolved
oxygen, and chemical composition" Alteration of preferred substrateo Alteration of intertidal areas" Increase in suspended organic or mineral material
" Reduction in food supplyo Reduction in protective cover (e.9., seaweed beds)o 0bstructjon of migration routes" Shock waves in aquatic environment" Human harvest (including handling of nonlegal crabs)
(See the Impacts of Land and hlater Use of this series for
additional impacts informat'ion. )
IX. LEGAL STATUSA. Manageria'l Authori ty
King crab fisheries throughout Alaska are managed by the State of
Alaska under regulations defined by the Alaska Board of Fisheries.
King crab fisheries in the Bering Sea-Aleutian area are managed
under a policy defined by the Alaska Board of Fisheries and the
North Pacific Management Council (McCrary 1984).
REFERENCES
ADF&G. L978. Alaska's fisheries atlas. Vol. 2 (R.F. McLean and
J . De1 aney , eds. ) . 43 pp. + maps .
ADNR/USFWS. 1983. Bristol Bay Cooperative Management Plan. Anchorage.
495 PP.
Bartlett, L.D. I976. King crab (family Lithodidae).
Pereyra et al . 1976.
395
Pages 531-545 in
Cunningham, D. 1969. A study of the food and feeding relationships of the
Alaska king crab, Paralithodes camtshatica. M.S. Thesis, San Diego
State Co11ege. Ci te,a-Tn Eier anffire T-ggt.
Eldridge, P. 1972. The king crab fisheries in the Gulf of Alaska. Pages2lI-266 in D.H. Rosenburg, ed. A neview of the oceanography and
renewable-resources of the northern Gulf of Alaska. tnitituie of
Marine Science. Rept. R72-?3. Univ. Alaska, Fairbanks.
Feder, H.M., A.J. Paul, M.K. Hoberg, S.L. Jewett, G.M. Matheke, K. McCumby,J. McDona'ld, R. Rice, and P. Shoemaker. 1980. Distribution,
abundance, community structure, and trophic relationships of the
nearshore benthos of Cook Inlet. N0AA/OCSEAP, final rept. Cited in
Feder and Jewett 1981.
Feder, H.M., and S.C. Jewett. 1980. A survey of epifaunal invertebrates ofthe southeastern Bering Sea with notes of the feeding biology of
selected species. Institute of Marine Science. Rept. R78-5. Univ.
Al aska, Fai rbanks.
. 1981. Feeding interactions in the eastern Bering Sea with
emphasis on the bentlios. Pages 129-126I in D.W. Hood anO i.A. Calder,
eds . The eastern Beri ng Sea shel f : Eeanography and resources .
Vol. 2. USDC: NOAA, 0MPA.
Gray, G.W., and G.C. Powell. 1966. Sex rat'ios and distribution of spawningking crab in Alitak Bay, Kodiak Island, Alaska. Crustaceana
10:303-309.
Haynes, E.B. 1968.in king crab,
58:60-62 .
Relation of fecundity and egg length to carapace length
Paral'ithodes camtschatica. Proc. Natl. Shellfish Assoc.
Haynes, E., and C. Lehman. 1969. Minutes of the Second Alaskan Shellfish
Conference. ADF&G, Informational Leaflet No. 135. Juneau. 102 pp.
Hilsinger, J.R. 1983. King and Tanner crab summary. ADF&G, Div. Conmer.Fish., memo for presentation at king and Tanner crab workshop.
Sa ndpo i nt.
. 1983. Personal communication. Mgt. Coordinator, Central Region,---TD-F&G, Div. Commer. Fish., Anchorage.
Jewett, S.C., and G.C. Powell. 1981. Nearshore movement of king crab.
Alaska Seas and Coasts 9(3):6-8.
Kulichkova, V.A. 1955. Feeding of Kamschatka crab during the spring
summer period on the shores of Kamschatka and Saghalin. Izv. TINRO.
Vol. 43. Cited in Feder and Jewett 1981.
396
Kurata, H. 1959. Studies on the larvae and post-larvae of Paralithodes
camtschatica: I, rearing of the larvae with special reference to food
oTTh-e zoea. Bull. Hokkaido Reg. Fish. Res. Lab. 20:76-83. Cited in
Feder and Jewett 1981.
. 1960a. Studies on the larvae and
Kun , M. S. , and L. V. Mi kul i ch. 1954.
of conunercial quality during the
in Feder and Jewett 1981.
camtschatica: II, feedingRes.-LailT:l-8. Cited in
Diet composition of far eastern crab
summer. Izv. TINR0. Vol . 4I. Ci ted
post-'larvae of -Paral ithodes
Bul I . Hokkaidd-R-eg.Tiffi
1975.
of Paral ithodes
sat iTffi on-tfi'e
Fish. Res. Lab.
the larvae and post-larvae of Paralithodes
the post-larvae. Hokkaido Fish.-Ex[ffi
Cited in Pereyra et. al. 1976.
habits of zoea.
Pereyra et al.
. 1960b. Studies on the larvae and post-larvae
camtschatica: III, the influence of temperature andffieT-na growth of larvae. Bull. Hokkaido Reg.2I:9-I4. Cited in Feder and Jewett 1981.
. 1961. Studies on
camtschati ca :growth of
18(1):1-9.Plo-nIFf+f
McCrary, J.A. 1984. Personal communication.
ADF&G, Div. Commer. Fish., Kodiak.
Asst. Regional Supervisor,
McLaughlin, P.A., and F.H. Hebard. 1961. Stomach contents of Bering Sga
k'ing crabs. USFWS Spec. Sci. Rept. 29I. Cited in Pereyra et. al.
1975.
McMullen, J.C. 1969. Effects of delayed mating on the reproduction of king
crab Paralithodes camtschatica. J. Fish. Res. Bd. Can. 26(10).
Manen, C.A., and H.E. Curl. 1981. Draft summary report of the shellfish
workshop. St. George Basin lease area synthesis meeting. Anchorage,
AK. April 28-30, 1981. 31 pp.
Marukawa, H. 1933. Biology and fishery research on Japanese king.crab
Paralithodes camtschatiCa (Tilesius). J. Imp. Exp. Sta., Tokyo 4(37).
gz0.
Merritt, M.F. 1985. Personal communication. Lower Cook Inlet Shellfish
Research Biologist, ADF&G, Div. Commer. Fish., Homer.
NMFS. 1983. Unpubl. data. Results of king crab study.
NPFMC. 1980. Alaska king crab draft fishery management p1an. Anchorage,
AK. 115 pp.
397
Otto, R.S. 1983-84. Personal communication. Laboratory Director, NOAA,
NMFS, NWAFC, Kodiak, AK.
Powell, G.C. 1979. Stars for kings. Sea Frontiers 25. Cited in Feder and
Jewett 1981.
. 1983. Personal communication.King Crab Research Biologist,-T-raG, Div. commer. Fish., Kodiak.
Powe11, G.C., and R.B. Nickerson. 1965a.
crabs (Paral ithodes camtschatjca
Aggregation among juvenile kingTilesius), Kodiak, AK. Animal
B e h a v i o u F-fF37i[]3-80 .
camtschati ca. 1965b. Reproduction of king crabs (Paralithodes
--fnlesiusl).
J. Fish. Res. Bd. can. Zz(1):10I:TIT.
Powell, G.C., and R.E. Reynolds. 1965. Movements of tagged king crab,
Paralithodes camtshatica (Tiksius), in the Kodiak Island-Lower Cookfi'lE-@n ofTT-aska, 1954-1963. ADF&G, Div. Commer. Fish.,
Informational Leaflet No. 55, Juneau.
Powe11, G.C., B. Shafford, and M. Jones. 1972. Reproductive biology of
young adult king crabs (Paralithodes camtschatica ITilesius]) at
kooiit<, Alaska. Pages 77W-n Proffr the National
Shellfisheries Association. Vol. 6T
Powell, G.C., K.E. James, and C.L. Hurd. I974. Ability of male king crab
Paralithodes camtshatica to mate repeatedly. Fish. Bull. 72(I).
Sindermann, C.J. 1970. Principal diseases of marine fish and shellfish.
New York: Academic Press.
Stinson, J.E. I975. The effects of ocean currents, bottom temperatures,
and other biologica'l considerations in regard to the location and
abundance of mature southeastern Bering Sea king crab, ?aralithodes
camtschatica.Univ.Washington,Fish.Res.Inst.catt.FEnffiFroEilIT pp. Cited in Pereyra et al. 1975.
Takeuchi, I. 1959. Food of king crab (Paralithodes camtschatica) off the
west coast of Kamchatka in igSA. Bu-Tl.-ffiRkalrlo-R-el--q. FlsF.-Res. Lab.
20:67-75. Cited in Feder and Jewett 1981.
Tarverdieva, M.R. I976. Feeding of the Kamchatka king crab .Paralithodes
camtshatica and Tanner crabi, Chionoecetes opi'lio 1n the sou[66aFEern
FaTiloilEa Bering Sea. Biolog!-Morya Z4lllSTransl . from Russian).
Cited in Feder and Jewett 1981.
398
Tsalkina, A.V. 1969. Characteristics of epifauna of the west Kamchatka
shelf (from problems of conunerciat hydrobiology). Fish. Res. Bd. Can.,
transl. Ser. No. 1568. Cited in Feder and Jewett 1981.
Wallace, M.M., C.J. Pertiut, and A.H. Hvatum. 1949.Contri buti ons
(Tilesius).
to the
USFl,lS,biology of the king crab Paral ithodes camtschatica
Fish. Leaflet 340. 50 pp.
399
Tlarmer Crab Life History and Habitat Requirements
Soutlrwest and Southcentral Alasha
=
c. balrdl
ffi c. oplfto
Map 1. Range of Tanner crab (ADF&G 1978; Kessler, pers. comn.;
0tto, pers. comm)
I. NAMEA. Common Names: Tanner crab, snow crab, queen crab, spider crab
B. Scientific Names: Chionoecetes bairdi, C. opiljo'
C. angu'latus, C. tahfrffi
II. EXTENT TO WHICH SPECIES REPRESENTS GROUP
Chionoecetes bairdi and Chionoecetes opilio are the o.n1y-species.
conunerc:i-ffi hii{6ted i nThilN'orEh-Pac-1Fiil( NPFMC 1981) . A hybri d
of C. bairdi and C. opilio occurs in the eastern Bering Sea. 1..tanneri-ffil-C. angulaFthough of minima1 commercial interest,
halE5-een fouid fiThe-Fring Sea and Gulf of Alaska.
401
III. RANGEA. Worldwide
Tanner crabs have a circum-arctic distribution, extending into the
temperate waters on the east and west coasts of North America.
C. bairdi occurs primarily in the eastern Pacific 0cean from 0regon
THosTe 1374) northward to the Aleutian Islands and the eastern
Bering Sea. q. bairdi a'lso exists in the western Pacific 0cean
near Kamchatka. !. gfl_l i 0. occurs from the eastern_ Beri ng- Sea
northward to the Feaufort Sea and in the western Atlantic Ocean
south to Casco Bay, Maine (Garth 1958). g. angulatus and C.
tanneri occur in teeper water in the Norfh FEFFTilfrom t-h'e
GTi-fornia Coast north to the Bering Sea (NPFMC 1981, Colgate pers.
comm).
Statewi de
C. bairdi occurs from Southeastern Alaska north to the southeastern
Eerlnffiea. 9. opilio occurs in the Bering Sea (ADF&G 1978).
Regi ona'l Di stri buti on Sununary
To supp'lement the d'istribution information presented in the text, a
series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250,000 scale,
but some are at 1:1,000,000 scale. These maps are available for
rev'iew in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition, a
set of colored 1:1,000,000-sca1e index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regiona'l guide.1. Southwest. Concentrations of C. bairdi occur in the Kodiak
T3-md;Bristol Bay, and SouTh -PEnTnsula/Aleutian Islands
areas. C. opiI'io occurs in the eastern Bering Sea, with
greatest -conGnTrati ons north of 58o north I ati tude. ( For
more detailed narrative informatjon, see volume 1 of the
Alaska Habitat Management Guide for the Southwest Region.)2. Southcentral. Concentrations of C. bairdi occur in the Prince
mfiTam-Sund and lower Cook Inlet areas. Smal I -sized Tanner
crab have also been found in upper Cook Inlet, primarily in
the Central District (Ky1e, pers. comm.). (For more detajled
narrative information, see volume 2 of the Alaska Habitat
Management Guide for the Southcentral Reg'ion.)
IV. PHYSICAL HABITAT REQUIREMENTSA. Water Qua'l 'ity
Adult distribution is restricted by low salinity and high tempera-ture. Laboratory experiments show that morta'lity of q. opilio
occurs if the crabs are exposed to sal inities of less than
22.5 parts per thousand (o/oo). q. opiljo reaches 50% mortality
after 18.8 days when the temperature has-61een held at 16'C (Mcleese
1968). C. bairdi is found in warmer slope and 0uter Continental
Shelf wa[erffihe southern Bering Sea where average temperatures
are 4.5"C. C. opilio is located in colder waters where the mean
temperature fi T3TINPMc 1981).
B.
c.
402
V.
B. Water Quantity
Tanner crabs bt atl sizes are abundant in water as shallow as 10 m
iOoritOion, p.ts. comm.). Juveniles occur at varying depths (NPFMC
iggt); they 'have been found to settle out a'lo-ng. the sea. bottom at
depthi bet-ween 298 and 349 m (Ito 1968). Crabs at sjze 6.5 mm
.a.upac. width (CW) off Kodiak lsland have been found at depths of
18 m', and at 12'mm size CW they have been located at depths of 55
io i6A r (flpfNC 1981). In Cook- tntet, early benthic stag-e-s (crabs
smaller than 20 mm) were found at depths greater than 50 m. In
this Same study, small crabs were most abundant at 15 and 166 m
depths (Paul tggZa). In Southeast Alaska ' many Tanner crabs
smitter ihan 40 mm have been located in Lisianski Stra'it as deep as
230 m (Carlson and StratY 1981).
Adult C. bajrdi and C. opilio have been found at respective depths
of 473-anffi[-m (t{pTuC-T98TJ. Major concentrations, however, are
restricted to depths less than 300 m (Somerton 1981).--!.. gngulEtus
occurs in deeper water, at depths to 2,972 m.-_-Generg_lly.' !.._!girgi-is found at'depths from shoal water to 473 m (Bering Sea to
California), and'C. opilio primarily occurs at depths of 13 to 155
m (Bering Sea, Arct'iilOfean, and the North Atlantic Ocean from the
west coait of Greenland to iasco Bay, Maine) (colgate 1983).
C. Substratepreferred substrate of C. bairdi has been described as green and
black mud, fine gray and-blaER-sand, and shell (Garth 1958). Post-
larval and juvenite- C. ba.!1.di near Kodiak Island have been observed
both 'in thii habitafanfrfr-among patches of epiphytic growth such as
hydroids and bryozoans. In Tower Cook Inlet, a nursery area for
j-uvenjle C. bairdi was found among dense centers of sponge-1ike
material (lewFT9ez).
NUTRITIONAL REQUIREMENTSA. Preferred Foods1. Larvae. Free-swimming larvae feed on plankton jn the water
col umn.2. Juveniles. The diet of iuveniles is uncertain. They are
SETieveri- to feed on detritus, crustaceans, and molluscs
accumulated on the sea floor (NPFMC 1981).
3. Adult. Identifiable stomach contents for c. opjlio and l.5ffili in the,Bering .Sea were primaril.y polychae-tes' crusta-
ceans, and molluscs- (Tarverdieva I976). !.. opil'i9 consumes
polychaetes and bri ttl e stars ( Feder and JewETT-1981) . In
Norton Sound, stomach contents of C. opilio jncluded clams
(Nucula tenuis) (Feder and Jewett 197-8). Important food items
io. -1; -5e1nf i n the Kod'iak area were arthopods (mai nly
juvenTle-e----6a'ird1), fishes, and molluscs .(Jewett and Feder
igaz). CTams lfl-qloqra spp. ), hermit crabs (Paqurus spp.,- and
barnacles (Balanffipp. ) were documented in stomachs of C.
bairdi in tb*ar-Caar iht6t. In Prince Wil'liam Sound, the diE't
oT-T bairdi contained polychaetes, clams,. !. bairdi,
crus-taceii3l-and detritus (Feder and Jewett 1981).
403
B. Feeding locations
Larvae feed in the water column; juvenile and adult crabs are
benthi c.C. Factors Limiting Availability of Food
Adverse climatic conditions may affect the availability of plankton
during the larval release period, and primary prey species may have
suffered a population decl ine, either or both of which
circumstances would I imit the availabil ity of food (Donaldson,
pers. comm. )D. Feeding Behavior
Larvae are planktivores; adults are benthic omnivores.
VI. REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat
Directed studies regarding preferred mating habitat have yet to be
performed.B. Reproductive Seasonal ity
Mating occurs during two overlapping periods in winter and early
spring: 1) females molting to maturity (primiparous) are mated by
males right after ecdysis during the winter, and 2) multiparous
females (carrying fu1 1y deve'loped eggs) undergo egg hatch and
either mate or use stored sperm to fertilize the new egg clutch in
the spring (Co1gate, pers. comm.; Paul et al. 1983). In laboratory
studies, if primiparous C. bairdi fema'les are not bred soon after
molting to maturity a sjgniTiran[ portion will not produce usable
eggs (Paul et al. 1983). The breeding season for C. bairdi near
Kodiak Island is from January to May (Donaldson 1975).C. Breeding Behavior
Males and females integrate on the mating grounds. It is suspected
that the male is attracted to the female by her release of a
chemical or chemicals (Adams 1979). Males mate with primiparous
females just after the females undergo terminal molt to maturity.
This puberty molt occurs only once in the female's life (Ito 1963,
Watson 1972). Spermatozoa are then transferred to and stored in
the female's seminal receptacles. Eggs released during future
ovulations may be fertilized by spermatozoa stored since the first
mating. If the female is unattended by a male during her molt to
maturity, ovulation may occur; however, the eggs wil I remaininfertile (Adams 1979). In captivity, old-shel I C. bairdi can
produce normal size egg clutches of viable eggs utilizing sperm
stored for two years (Paul et al. 1983). Male Tanner crabs are
capable of mating at the size at which they reach maturity
(Dona'ldson 1975). A male may fertilize up to six females in one
season (Watson 1972).D. Age at Sexual Maturity
Female Tanner crabs reach sexual maturity at about five years and
ma'les at six years (Donaldson, pers. comm.). Female C. bairdi
undergo their iinal molt as they reach maturity (DonalOson et aT.
1981 ). Studies i n the Gul f of Al aska have shown the size of
females at 50% maturity to be about 83 mm, reach'ing about 97 mm at
404
E.
the molt to maturity. Among males, 90 mm appears to be the size at
which the molt to maturity occurs. Such an animal would grow to
112 mm. The stage at which terminal molt occurs for male Tanner
crabs is still unknown (ibid.). In the Sea of Japan, maturity of
male C. opilio occurs 'in six to eight years (lto 1970, Sinoda
1968).- In ttr-e Gulf of Alaska, it is estimated that iust over s jx
years is requ'ired for the average male Tanner crab (C. bairdi) to
reach maturity (Donaldson et al. 1981). Little difference in
average size ai sexual maturity is apparent among areas (ibid.).
Fecund i ty
The fecundity of Tanner crabs increases from their first to their
second reproductive year, then decreases s'light'ly in succeeding
years. Fecundity may be less the first year.because of the energy
iequirements of the first molt (Somerton 1981). The number of eggs
carried by the female is a linear function of carapace width
(Hilsinger 1975). In the Bering Sea, the fecund'ity range for C.
bairdi is from 89,000 to 424,000 eggs (NPFMC 1981) and in the GuTf
of A-Ti-ska,85,000 to 23I,000 eggs (Hilsinger 1975). The fecundity
of C. opilio in the Gulf of St. Lawrence has been found to range
frofr- Z0lffi-O to 40,000 eggs (t^latson 1969). The average percentage,
by location, of adult females not carrying egg clutches between
L977 and 19Bl were as fol I ows : Kodi ak , 5.8%; the eastern
Aleutians, 2.3%; Sand Point,3.6%; and Cook Inlet,3.5%.
Frequency of Mating
Complete- hardening- of the shell (exoskeleton) may occur 16 to 7I
days after the mol t (Adams 1982 ) . However, ol d-shel 1 mature
females have been found capable of mating after the terminal molt
(Donaldson L977). The point at which male C. bairdi undergo
iermi nal mol t i s undetermi ned ( Donal dson - et aT. 1981 ) .
Primiparous, or first-mating, female C. bairdi mate and deposit egg
clutches from mid winter to ear'ly -spFlng. Multiparous females
hatch clutches and deposit new eggs in the spring. Primiparous
females must breed within one week after the final molt in order to
produce viable egg clutches (Pau1 1982b). Male C. bairdi can mate
twice on the sam6-day or several t'imes within a lee'k-Tnlaptivity.At each occurrence, mal es typi ca1 1y depos i t enough sperm to
fertilize several egg c'lutches (Paul et al . 1983). In the Kodiak
area, scuba divers observed males of 70 to 160 mm (average 112 mm)
carapace wi dth graspi ng pubescent femal es . Mal es were a1 ways
larger than the females they grasped. In the laboratory, free
clutches of viable eggs were produced by primiparous females whose
mates were 65 to 140 mm'in carapace width. Even though the sizesof the males these females mated with were variable over 90% had
sufficient numbers of stored sperm to fertiljze subsequent egg
clutches (ib'id.).
Incubati on Peri odlEmergence
Eggs are fertilized as they are released and are retained in the
biood chamber, where they remain 11 months to a year (Bartlett
1976, Somerton 1981). The spring egg hatch is synchronized to the
availability of prey food (Ito 1967, Watson 1970). Egg hatching
F.
G.
405
('larval release) appears to coincide with plankton blooms (NPFMC
ig8t). Peak hatching in the Bering Sea occurs in mid May (Drury
1980). In the southeastern Bering Sea, larvae of !.. opilio
appeared in plankton two weeks prior to the hatchout of C. bairdj.
Lii^va'l develbpment of Tanner crdU is dependent upon the tEmperailure
regime and the condition of the piankton on which they feed (Incze
et- al . 1982) . Free-swimmi ng I arvae mol t and progress through
several di sti nct stages pri or to settl i ng to the bottom asjuveniles. Growth rates from the larval to the juvenile stages are
dependent upon temperature (NPFMC 1981). In Wakasa Bay (Sea of
Japan), the developmental period between the larval and iuvenile
stages for C. opilio may last about 63 days at water temperatures
of 11 to 13TC lRon-T970). The duration of the development to each
zoea'l stage is a minjmum of 30 days (Incze et al. 1982). The
duratjon of the megalops stage may be longer than 30 days for
larvae of both q. gpilio and C. ba'irdi (ibid. ). The size of
juvenile crabs betweEfr--m6lts 'incTeaffiFom about 25% to 36% for
each of the first six molts preceeding the molt to maturity
(Donaldson et al. 1981).
VII. MOVEMENTS ASSOCIATED t^lITH LIFE FUNCTIONSA. Larvae
Tanner crab larvae are free-swimming. In the Sea of Japan, where
spawning occurs from January to Apri't , prezoae (Chionoecetes spp. )
swim from depths of 225 to 275 m almost direct'ly toward the sea
surface after phototaxis (Kon 1967). From March to May in the Sea
of Japan crabs at the second zoea stage inhabjt depths of 25 to
100 m, and'in May they drop to 150 to 200 m as a result of increas-
ing sea-surface temperatures (Kon 1982). In the Sea of Japan, the
metamorphosis from the second zoea stage to megalops occurs in
early Apri'l at 150 to 200 m, where the temperature ranges from 6 to
12"C. After metamorphos'is, zoea move to a deeper stratum (Kon
1969). In the southeastern Bering Sea, sea ice may influence the
distribution of C. opilio by affecting the food supp'ly and phyto-
p'lankton bloom (Somerton 1982). Larvae do not show distinct depth
stratifjcation by s'ize, though the species form aggregations of
like individuals at the same stage of development upon metamor-
phosis. Distribution of megalops is patchlike on the substrate'
where like groups seek a particular habitat, and are not arranged
as bands along depth contours (NPFMC 1981). Plankton studies
i ndicate that I arvae undergo di urnal vertical migrati.ons ! n
response to the movement of the p1 ankton bl oom ( ibid. ) .
Distribution of Chionoecetes (spp. ) in the Sea of Japan is
associated with upweTfinag -[AbE 1977). The direction and magnitude
of currents in the Bering Sea do not transport C. opilio and C.
bairdi larvae off the continental shelf (Kjnder and Schumacher
Tmzl.B. Juveni I e
Environmental factors such as ocean currents and water temperature
determine the depth and location at which iuvenile Tanner crabs
406
settle (Adams 1979). Juveniles settle out. along the sea bottom at
depths between 298 and 349 .m ( I to 1968) . _ The _di s.tri buti on of
juvenile crabs is widespread (NPFMC 1981). The rela-tive abundance
6f adults and juvenilei differs between species: for C. opilio,
some areas wherb juveniles are found to occur harbor few adults'
and for C. bairdi the opposite is true. Both iuveniles and adults
occur througmu-t their range in the eastern Bering Sea. In Brjstol
Bay, maturJ C. opilio and C. bai$ are sedentary and remain in
idbntifiable ?ohoiEi-near thE affi-here they mature.
C. Adul ts
Tagging studies show that adu'lt !.. bair.di perform only I im'ited
movemeits, averaging 15 mi around T-odjaR--[D-ona]dson, pers. conrn. ),
that are neithei directional nor c'learly seasonal. Mature males
perform their seasonal breeding migration apparent'ly at random,
iossibly guided by pheromones -released by the female. In the
bering SeJ, C. balrdf segregate by size group. Vertical migration
is no1 obviousJfip-lt'tc i981). At about f ive years of age for
females and six years of age for males, the two sexes separate into
sex-specific schools (ADNR/USFWS 1983). Femalg L.. tanneri are
seaentiiy and males migratory. During winter _(from WdEffi!'Fon..to
California), males move to depths occupied by females for breeding
and return to shallow water after a short period of mixing with
females (NPFMC 1981).
Distribuiion of C. opilio is related to the edge.of the sea ice in
the eastern Bering ffis the sea ice affects phytoplankton bloom
and food availability (Somerton 1982).
VIII. FACTORS INFLUENCING POPULATIONSA. Natural1. Predation. Most information regarding predation is on larval
cFE[il-Few reports are avai I abl e on the predati on of
juveniles and adults. The best data are available for q.
opiiio,-!. uuiioi, and C. opilio elongalus. A total of 37
pffi-tors have Ueen documented as_ preying upo_n .the genus
bhionoecetes from d'ifferent areas. Predators include at least
7 sperr: of invertebrates, 26. species of fish, and 4 spec'ies
of marine mammals (Jewett 1982).a. Eggs. Predation on eggs by the nemertean worm
@ spp. ) hta been documented (Hi1s'inger
197T).b. Larvae. Chionoecetes (spp. ) is the most frequently
Teo-orted ffiT6:F-upon Chionoecetes. Large crabs
(gi^eater than 40 mm bw) near Ro?iia-k-Island were more
cinnibalistic than small crabs (less than or equa'l to
40 mm). Red k'ing crabs (Laratithodes c!rn!$3-Usg.) have
be e n d o c u me n t e d i
-n
ro a i a k'afril-Ttr'e-EE-r i n g_Sila- d a t o r s
of Tanner crabs where distributions overlap. In the
Kodiak area, stomachs of king crabs greater than or equal
to 65 mm CW contained juvenile C. bairdi. Tanner crabs
have al so been documented as d-omi nant-prey for Beri ng
407
skates (Raja interrupta), Alaska skates (R. parmifqlq),
and wottle-d ee@ palearis). I. EI'TniITrom
1.8 to 70 mm CW'have b6n-frcu-inented as m6-stElTently
occurring prey for Pacific cod taken near Kodiak Island
dupfing the months of June and July. An estimate of 1.5 x
10" crabs are eSten annually by the Kodiak cod popula-
t'ion of 6.9 x 10' fish (Jewett 1982). Tanner crabs have
comprised a large percentage of diets for four species of
sculpins (cottidae). In the Gulf of A'laska and Kodiak
Is'land area , ye1 1ow Iri sh I ords (teqilepflglgr iordani )
and the great -scul pi n (Nyoxocephal us doTy:-affiocepfaTus )preyed sign'ificantly upon Tanner crabs. The great
scul pi n seems to prefer mature femal e Tanner crabs
(Hilsinger, pers. conrm. ). Flatfishes (Pleuronectidae),
part'icular'ly the rock sole (Lepidopsettia bil jniata),
were found to feed on Tanner TEEs. fi-the-noTTheFly
areas of the Bering Sea, Tanner crabs are especial'ly
important as prey of bearded seals (Jewett 1982).c. Adult. Predators upon adults. include Pacific cod and
ocTopuses (E1 l son et al . 1950) . Adul ts appear to have
few predators, though those in molt would be vulnerable
to large fish, octopuses, and sea stars (Hilsinger, pers.
comm. ).B. Human-rel ated
A sunrnary of possib'le impacts from human-related activites includes
the fol 1ow'ing:
o
o
Alteration of preferred water temperatures, pH, d'issolved
oxygen, and chemical composition
Alteration of preferred substrate
Alteration of intertidal areas
Increase in suspended organic or mineral material" Reduction in food supplyo Reduction in protective cover (e.9., seaweed beds)o 0bstruction of migration routeso Shock waves in aquatic environmento Human harvest (including handling of nonlegal crabs)
(See Impacts of Land and Water Use in this series for additional
information regarding impacts. )
IX. LEGAL STATUSA. Manageri a'l Authori ty
The Tanner crab resource is managed under a ioint State-Federal
Fisheries Managment Plan covering all management areas. The Alaska
Department of Fish and Game regulates the fishery in areas where
most fishing occurs in territorial waters (Lower Cook Inlet, Prince
Willa'im Sound, Yakutat, Southeastern Alaska) and manages jointly
with the National Marine Fisherjes Service (NMFS) where significantfisheries exist beyond 3 mi. In Kodiak, South Peninsula,
Aleutians, and Bering Sea areas, both state and federal emergency
orders are jointly issued to close or open fisheries. The NMGS
408
X.
manages the foreign fishery, and both state and federal managment
regimes are guides by policies in the F'ishery Management Plan
developed by the North Pacific Management Council in coordination
with the Aliska Board of Fisheries (McCrary 1984).
LIMITATIONS OF INFORMATIONLjttle information is available on the early life history of the Tanner
crab, its migrational patterns, and the causes of its morta'l ity.
Reliable techniques for calculating the age of Tanner crabs need to be
devel oped.
RE FERENCES
Adams, A.E. 1979. The life history of the snow crab, Chionoecetes opilio:
a literature review. Univ. Alaska, Sea Grant Rept. 78-13.
. 1982. The mating behavior
otthe international symposium on
Sea Grant Rept. 82-10.
th@.of Chionoecetes baird'i .In Proceedings
-unjv. Alaska,
ADF&G. 1978. Alaska's fisheries atlas. Vol.
K.J. Delaney, comps.l. 43 pp. + maps.
2 [R. F. Mclean and
ADNR/USFhlS. 1983. Bristol Bay Cooperative Management Plan. Anchorage.
495 pp.
Bartlett, L.D. 1976. Tanner crab (fam'ily Maiidae). Pages 545-556 in
1^1.T. Pereyra, J.E. Reeves, and R.G. Bakkala, eds. Demersal fjsh anE
shellfjsh resources of the eastern Bering Sea in the baseline year of
1975. USDC. Processed rept.
Carlson, H.R., and R.R. Straty. 1981. Habitat and nursery grounds of the
Pacific rockfish, Sebastes sp.p. 'in rocky coastal areas of Southeastern
Alaska. Mar. Fish.-Review 43(7).
Colgate, W.A. 1983. Technical report to industry on the Westward- _Region- Tanner crab, Chionoecetes bairdi, population index surveys. ADF&G, Div.
Commer. Fish., Kodiak. 70 pp.
. 1984. Personal communication. Tanner Crab Research Biologist'----T-F&G, Div. Commer. Fish., Kodiak.
Donaldson, lrJ.E. 1975. Kodiak Tanner crab research. Unpubl. tech. rept.
ADF&G, Kodiak.
. 1977. Kodiak Tanner crab research. ADF&G completion rept.
-Prqi.
5-34-R. Commercial Fi sheries Research and Devel opment Act.
6o pp.
409
. 1984. Personal communicat'ion. Habitat Bio'logist, ADF&G, Div.
-T5'ltat,
Anchorage.
Donaldson, hl.E., R.T. Cooney, and J.R. Helsinger. 1981.. Growth, age.and
size at maturity of Tanner crab, Chjonoecetes bairdi (M..J. Rathburn) in
the northern 'Gulf of Alaska rcoopoAtu -BiaEfi"ywa). Crustaceana
40(3):286-302.
Drury, 14.H. 1980. Ecological studies in the Bering Strait region. Fl'|. 237,
final rept. to 0CSEAP. 308 PP.
Ellson, R.G., D.E. Powell, and H.H. Hildegrand. 1950. Exploratory fish'ing
expedition to the northern Bering Sea in June and July' 1949. USFblS'
Fish Leaflet 369. 56 pp.
Feder, H.M., and S.C. Jewett. 1978. Survey of the epifaunal invertebrates
of Norton Sound, southeastern Chukchi Sea and Kotzebue Sound.
Rept. 78-1, Institute of Marine Science, Univ. Alaska, Fairbanks.
. 1981. Feedi ng i nteractions i n the eastern Bering Sea with
emphasis on the benthos. Pages 1229-1261 in D.}J. Hood, and J.A. Ca'lder'
ed!. The eastern Bering Sea shelf: oceano!-raphy and resources. Vol. 2.
USDC:0MPA, NOAA.
Garth, J.S. 1958. Brachyura of the Pacific Coast of America. Allen Hancock
Pacific Expeditions. Vol. 27. Univ. Southern California Press.
854 pp. Cited in NPFMC 1981.
Hilsinger, J.R. 1,975. Some aspects of the reproductive biology of female
snow crab (Chionoecetes bairdi). Institute of Marine Science, Univ.
A]aska, FairFankslffil inie-reyra et al . L976.
. 1984. Personal communication. Mgt. Coordinator, Central Region,
TF&G, Div. Commer. F'ish., Anchorage.
Hosie, M.J. L974. Southern range extensjon of the Bairdj crab, Chionoecetes
bairdi Rathbun. Cal'if. Fi;h and Game 60(1) :44-47. Citedln5niFFTo'n'
L98T.
Incze, 1.S., D.A. Armstrong, and D.L. t^lencker. 1982. Rates of development
and growth of larvae of Chionoecetes bairdj and 9. qpilio in the
south-eastern Bering Sea. Proceedm's of Th'e-I-nternatTonaT syrnposium on
the genus Chionoecetes. Univ. Al.aska, Sea Grant Rept. 82-10.
Ito, K. 1963. A few studies on the ripeness of eggs, zuwigani.(Chionoegetes
opilio). Bull. Jap. Sea Reg. Fi.sh. _Res. Lab. 2:65-76. (Transl. Fish.
Res. B'a. Can., Transl. Ser. 111.7). Processed rept. USDC.
410
Jewett, S.C., and H.M. Feder.
bairdi near Kodiak Island'
lyffiium on the genus
Rept.82-10.
. 1967. Ecological studies on the edible crab, Chiolgecetes opilio,
--f0; Fabricus) in tlie Japan Sea. I: When do female crabs first sp_awn-and
how do they advance into the fol'lowing reproductive stage. Bul1. -Jap.
Sea Reg. iisrr. Res. Lab. L7267-84. - (Transl. Fish. Res. Bd. Can.,
Transl. Ser. No. 1103.)
. 1968. Ecological studies on the edible crab, Chionoecete.s opil]9
-lTT
Fabricus) in fne Japan Sea. II: Description_of y9Yn9 crabs' yilh
note on their distribution. Bull. Jap. Sea. Reg. Fish. Res' Lab'
19:43-50. (Transl. Fjsh. Res. Bd. Can., Transl. Ser. No. 1184.)
. 1970. Ecological studies on the edible crab Chionoqcetes. opilio
-(0:
Fabrjcus) in the Japan Sea. III: Age and growt!.a9 eltimated on one
Uasis of th; seasonal changes in the carapace width freque_n_ci_es q1d
carapace hardness. Bull. Jup. Sea. Reg. Fish. Res. Lab. 22zBL-Il6'
(iralrsl . Fish. Res. Bd. Can., 'Transl . Ser. No. 1512. )
Jewett, S.C. 1982. Predation on crabs of the genus Chingecetes: literature
review. froceeAlngs of the internationil sympoTTufrln the genus
Chionoecetes. Univ. A1aska, Sea Grant Rept.82-10.
1982. Food of the Tanner crab Chionoecetes
Alaska. Proceedings of the inEFneffinaT
Chionoecetes. Univ. Alaska, Sea Grant
Kessler, R. 1984. Personal communication. Shellfish Biologsit' N0AA, NMFS'
NWAFC, Kodiak' AK.
Kinder, T.H., and J.D. Schumacher. 1982. Circulation over the Continental
Shelf of the southeastern Bering Sea. Pages 53-75 in D.W. Hood and
G.A. Calder, eds. The eastern Bering Sea shelf: oceanography and
resources. Vol. 1. USDC: 0MPA, N0AA.
Kon , T. 1967 . Fi sheri es bi o'logy of the Tanner crab. I : 0n the prezoea'l
lanvae. Bull. Jap. Soc. SCi. Fish.33(8):726-730. (In Japanese' with
Engl ish Summary)
. 1969. Fisheries biology of the Tanner crab. III: The density
-T-i
stri buti on and carapace w'id-ih composi ti on i n rel ati on to the _depth.
Bul'1. Jap. Soc. Sci. Fish.35(7). (Transl. Fish. Res. Bd. Can., Transl.
Ser. N0.1363)
. 1970. Fisheries biology of the Tanner crab. IV: The durat'ion of--The plinktonic stages estimalid by rearing_ experimglt of ^larvae. Bull.
Jap.' Soc. Sci. Fiil!. 361(3) ;219-224. (Transl . Fish. Res. Bd. Can.,
Tranl. Ser. No. 1603)
411
. 1982. 0n the p1 anktoni c I arvae I i fe of the zuwai crab ,
Tonoecetesopiljo'occurringa1ongthecoastofthecentralJapanSea.
mceed-Ings oFthe international symposium on the genus Chionoecetes.
Univ. Alaska, Sea Grant Rept.82-10.
McCrary, J.A. 1984. Personal communication. Asst. Regional Supervisor'
ADF&G, Div. Commer. Fish., Kodiak.
McLeese, D.W. 1968. Temperature resistance of the spider crab, Chionoecetes
opilio. J. Fish. Scj. Bd. Can.25(8):1733-1736.
NPFMC. 1981. Fishery Management P'lan for the conmercial Tanner crab fishery
off the coast of Alaska. Anchorage. 197 pp.
Otto, R.S., 1984. Personal communicatjon. Laboratory D'irector, N0AA, NMFS,
NWAFC, Kodiak, AK.
paul, J.M. 1982a. Distribution of Juvenile Chionoeceleq bairdi 'in Cook
In'let. Proieedings of the internationa-i$[6Effi ln-ttre genus
Chionoecetes. Unjv. Alaska, Sea Grant Rept. 82-10.
. 1982b. Mating frequency and sperm storage factors affecting
FF6-duction in multiparous Chionoecetes. bairdi. In Proceedings.of
international symposium on@. Univ. Alaska,
Grant Rept.82-10.
Paul, A.J., A.E. Adams, J.M. Pau1, H.M.
Some aspects of reproduct'ive bi o'logy
Univ. Alaska, Sea Grant RePt. 83-1.
Sinoda, M. 1968. Studies on the fishery of zuwai crab in the Japan Sea.
Ph.D. Thesis submitted to Dept. Fish., Kyoto Univ., Japan.
Somerton, D.A. 1981. Ljfe history and popu'lation dynamics of two species-of
Tanner crab, Chi onqgpelg_l bai rdi and C . opi I j o, i n the eastern Beri ng
Sea wi th implTcaTi ons fo-r-IfiImanagehenil6T-the commerci al harvest.
Ph.D. Dissert., Univ. Wash., Seattle. 211 pp.
. 1982. Effects of sea ice on the distribution and population--mctuations of C. opilio in the eastern Bering Sea. Proceedings of the
international sympoffim-on the genus Chjonoecetes. Univ. Alaska, Sea
Grant Rept.82-10.
Tarverdieva, M.J.
camtschati ca ,
opTTTo Tn The
B'ioT. z:34-39.
I976. Feeding of one Kamchatka king crab Paralithodes
and Tanner crabs, Chionoecetes bairdi and Chionoecetes
southeastern pari oT-The-ffindTa. Sov.-J.--f,fiElT
Cited in Feder and Jewett 1981.
egg
the
Sea
Feder, and t,l.E. Donaldson. 1983.of the crab Chionoecetes bairdi.
412
51atson, J. 1969. Biolog'ica1 investigations on the spider crab, Chionoecetes
opitio. Proceedingi Atlantic crab fisheries deve'lopment. -ean. Tish';
Rept. L3:24-27.
. 1970. Maturity, mating and egg laying in the spider crab,
@ opilio. J. Fish. Res. Bd. Can. 2721607-1616.
. I972. Mating behavior in the spider
-T-fisfr. Res. Bd. Can. 29(4):447-449.
crab Chionoecetes opilio.
413
Razor Clam Life History and Habitat Requirements
Soutlrwest and Southcentral Alasha
aa
I.
II.
Map 1. Range of razor clam (Nickerson 1975)
NAMEA. Common Name: Razor clam
B. Scientific Name: Si'liqua patula
RANGEA. Worldwide
The razor clam is found from Pismo Beach, Ca'lifornia, to the
Bering Sea (Amos 1966).B. Regional Distribution SurmarY
To-supplement the distribution information .presented in. the text'
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this ieries are at 1:250,000 scale'
bui some are at 1:1,000,000 scale. These maps are avai.lab'le for
review in ADF&G offiies of ttre region or may be purchased from the
a ' ,'{^o "$*
415
contract vendor responsible for their reproduction. In addition'
a set of colored 1:1,000,000-sca'le index maps of se'lected fish and
wildlife spec'ies has been prepared and may be found in the Atlas
that accompanies each reg'ional guide.
1. Southwest. Commercial quantities of razor clams in Southwest
Elfficur on beaches in the Swikshak area of the Alaska
Peninsu'la (Paul and Feder 1976). (For more detailed nar-
rati ve i nformation, see vol ume 1 of the Alaska Habi tat
Management Guide for the Southwest Region.)
2. Southcentral. Cornnercial quantities of razor clams in
SffittIE.T Alaska occur on beaches near Cordova and on the
west side of Cook Inlet (ibid.). Large populations of razor
clams are also found on the east side of Cook Inlet, where an
active razor clam persona'l use harvest occurs. (For more
detailed narratjve information, see volume 2 of the Alaska
Habitat Management Gujde for the Southcentral Region.)
III. PHYSICAL HABITAT REQUIREMENTSA. Water Quantity
Razor clams are found intertidally to a depth of severa'l meters
(Keen 1963) on exposed beaches of the open coast (Nosho 1972).
Nickerson (1975) found the highest density of razor clams to be at
the 0 tide' level (0 corresponds to the 'level at mean 'low water),
with the upper habitable tide leve'l estimated to be +4.50 ft at
Cordova. He specu'lated that the upper habi tab'le I evel i s rel ated
to the tidal regime and therefore varies from one area to the
next, with the highest estimated habitable level being +6.26 ft at
Po11y Creek on west side of Cook Inlet (Nickerson 1.975, calculated
from values arrived at jn his Cordova study).
Nickerson also found that'larger and older clams are found at
lower tide levels, possibly because clams at lower levels are
exposed to more nutrient-bearing sea water. McMul len ( 1967),
however, di d not f i nd thi s rel ati onsh'ip to be va'l i d for razor
clams collected at tide levels ranging from -5.0 to -1.1 at Clam
Gulch and Deep Creek beaches on the east side of Cook Inlet.
B. Water Temperatures
Sayce and Tufts (tglZ), in 'laboratory experiments, found that
razor clams suffered 100% morta'lity when exposed to 25oC seawater
for a period of eight hours. Sayce and Tufts_speculated that
razor clams on Washington beaches may infrequently be exposed to
these high temperatures and that mortality from high temperatures
may account for some of the fluctuations in razor clam populations
jn Washington.C. Substrate
Productive beaches include those consisting of fine sand with some
glacial silt (Kar'ls Bar at Orca Inlet near Cordova), fine sand,
volcanic ash and some qlacia'l mud (Swikshak and Hallo Bay near
Kodiak), coarse white slnd (Deep Creek area of Cook Inlet), and
fine sand-c'lay-gravel mjxture (C1am Gulch on Cook Inlet).
476
IV.
Nickerson (tgZS) and Nickerson and Brown (1979) found an jnverse
re'lationsh'ip between substrate clay levels- and the density of
one-year-o1d razor clams. When the level of fine substrate
particles (0.005 nm in diameter) reached 2.2% or more' one-year-
old razor clams were not found.
NUTRITIONAL REQUI REMENTSA. Food Species Used
Razor clams are filter
p]ankton (ADF&G 1978) .
feeders, consuming detritus and drifting
B. Types of Feeding Areas Used
Razor clams feed within the intertidal zone.
C. Factors Limiting Availability of Food
Nickerson (1975) noted that larger c'lams are found at lower tide
levels and'speculated that theii apparently faster growth may_be
due to 'longer exposure to nutrient-rich sea water. Razor clam
growth acceieratei in spring, when the fo.od gupqly_^increases, and
continues at a rapid rate through summer (Nosho 1972).
Nelson OggZ) noted that investlgators dealjng with_other species
of clams have found that heavy concentrations of adult clams in an
area may reduce the food suppty and adversely affec-t the survival
of juveniles, which are not as able to compete for food and s_pace.
He (tgAZ) speculated that these observatjons may also apply to
razor cl ams.D. Feeding Behavior
Adult iazor clams lie buried in the sand, their siphons protruding
above the surface. Food particles are brought in along with water
through the incurrent tube, then are filtered out of the water by
the gi]ls and passed to the mouth for ingestion (ADF&G 1978).
V. REPRODUCTIVE CHARACTERISTICSA. Reproductive Habitat
Ra2or clams breed within the intertidal zone.
B. Reproductive Seasonal itY
noiho (1972) states th-at razor clam spawning occurs when water
temperatures reach 13oC, which usual'ly occurs in July in Alaska.
Ni ckerson ( 1975 ) , however, f ound that the onset of s.p.aw-1i ng. i s
. more strongty reiated to cumulative temperature units._(defined.as
the cumulaiive degrees IFahrenheit] of the maximum dai!V deviation
t32 F that were observed from January 1. to the time of spawning).
He found that spawning occurred when I,350 or more tempgr-ature
unjts had accumu'lated,- usually between late May and mid July in
the Cordova area (ibid.).
C. Reproductive Behavior
Spiwning occurs over a period of several weeks (Nosho L972). Eggs.
aira sp-erm are rel eased through the excurrent si phon, and
iertilization takes p]ace in the open water (ibid.).
D. Age at Sexual MaturitY
Ritainment of sexual maturity is more closely related to size than
age (Nickerson 1975), c'lami reaching maturity at a length of
417
approximate'ly 100 mm (Nosho. I972, McMu'llen 1967). Growth rate
(and thus age at maturity) varies greatly among populations.
Spawni ng of Cl am Gu1ch razor cl ams , for examp'le, may occur as
early as age two (McMullen 1967), whereas 65% of clams on Cordova
beaches reach maturity at age three (Nickerson 1975).E. Frequency of Breeding
Razor clams breed annually (Nelson 1982).F. Fecundity
Fecundity of female razor clams increases with s'ize. Nickerson
(1975) found that fecundity estimates of razor clams 40 to 180 mm
(valve length) ranged from 0.3 to 118.5 million ova per c'lam.G. Incubation Period
Eggs hatch into free-swirnming, ciliated larvae (veligers) within a
few hours to a few days of release, with the rate of development
dependent on temperature. Larvae exist as free-swirming veligers
for 5 to 16 weeks (Oregon Fish Cornnissjon 1963), after which they
develop a shell and settle to the bottom.
VI. MOVEMENTS ASSOCIATED t,lITH LIFE FUNCTIONS
C'lam ve'l i gers are dependent upon water currents to carry them to
desirable habitat (ADF&G 1978).
Young razor cl ams up to 1Omm (va1 ve 'length ) are capabl e of . vo'l untary
lateial movement along the beach surface to about 60 cm (Nickerson
1975). Large razor clams are believed to be incapable of voluntary
lateral movement, though relocations may occur as a consequence of
rapid'ly shifting substrate, or washout (ibid. ). Razor clams are,
howevei, capable of very rapid vertical movements (several feet per
mi nute ) .
VII. FACTORS INFLUENCING POPULATIONSA. Natural
Mortality of larval and juvenile stages is extremely high, and
their surv'ival, rather than the number or fecundity of spawning
adults, is believed to determine the size of each year class
(Nelson 1982).
Razor clams in the veliger stage are preyed upon by plankton
feeders. Veligers are dependent upon favorable water currents to
wash them to desirable settling habitat (ibid.).
Reduced food concentrations retard growth and may weaken iuveniles(ibid.).
Survival of year classes of razor clams is h'ighly variable.
McMullen (1967) attributed the apparently weak 1965 year class at
C'lam Gulch to unseasonab'ly cold weather that delayed spawning thatyear. The young clams were probably not ready to settle untilfall, when low tides and cold weather exposed and froze them.
Influxes of freshwater, caused by high-flowing streams or heavy
rain, result in increased mortality of adult and young razor clams
(ib'id.).
418
Adult razor clams are consumed by starfish, drilling snails,
crabs, rays, octopuses, flatfishes, ducks, and gu11s (Feder and
Paul t974, ADF&G 1978).B. Human-rel atedA summary of possible impacts from human-related activities
includes the following:
" Alteration of preferred water temperatures, PH, dissolved
oxygen, salinity, and chemical compositiono Introduction of water-soluble substanceso Alteration of preferred water circulation patterns and deptho Increase in su.spended organic or mineral materialo Increase in siltation -and reduction in permeability of
substrate" Reduction in food suPPlY
" Seismic shock waves
" Human harvest
(See the ImPacts of Land and Water
additional impacts information. )
VI I I. LEGAL STATUS
Use volume of this series for
Sport and commercial harvests of razor clams are regulated
Alaska Department of Fish and Game.
by the
REFERENCES
ADF&G, comp. 1978. A fish and wildlife resource inventory of the Prjnce
!{illiam Sound area. Vol. 2: Fisheries. Juneau. 241 pp.
Amos, M.H. 1966. Commercial clams of the North American Pacifjc Coast.
USFWS. Cjrc. 237. 18 pp. Cited in Nosho 1972.
Feder, H., and A.J. Paul. 1974. Alaska clams: a
Alaska Seas and Coasts 2(1): I,6'7.
Keen, A.M. 1963. Mari ne mol I uscan genera'l of
Stanford, CA: Stanford Univ. Press. 126 pp-
McMullen, J.C. 1967. Some aspects of the life
resource for the future.
western North America.
Cited in Nickerson 1975.
history of razor clams
ADF&G, InformationalSilqua patula (Dixon) in Cook Inlet, A'laska.
Nelson, D.C. 1982. A review of Alaska's Kenai Peninsula east side beach
recreational razor clam (Silqua patula, Dixon) fishery,1965-1980.
Unpubl . MS. ADF&G, Div. Sport-fishf766' pp.
Nickerson, R.B. 1975. A critical analysis of razor clam (Si'lqua patu'la,
D'ixon) populations in Alaska. ADF&G, Div. FRED. 194 pp.
Nickerson, R.B., and T.J. Brown. 1979. The effects of an experimental
hydriulic harvester on marginal and submargina'l razor clam (Silqua
419
patula, Dixon) habitat on the Copper River delta, Cordova, A'laska.
mFEe Informational Leaflet No. I79. 19 pp.
Nosho, T.Y. L972. The clam fishery of the Gulf of Alaska. Pages 351-360
in D.H. Rosenbergr ed. A review of the oceanography. and renewable
resources of the Northern Gu'lf of Alaska. Univ. A]aska, Inst. Mar.
Sci. Rept. No. R72-23 (Alaska Sea Grant Rept. 73-3).
0regon Fish Conrnission. 1963. Razor c'lams. Educ. Bull. 4. Portland, 0R.
13 pp. C'ited in Nosho 1972.
Pau'f , A.J., and H.M. Feder. 7976. Clam, mussel and oyster resources of
Alaska. Alaska Sea Grant Rept. AK-56-76-6. 41 pp.
Sayce, C.S., and D.F. Tufts. 1972. The effect of high water temperatule-o!'l- the razor clam, Siliqua patul,a (Dixon). Proc. National Shellfish
Assoc. 62:31-34.
420
Shrimp Life History and Habitat Requirements
Soutlrwest and Southcentral Alasha
I.
tt*r,,'ili:::::l:'
Map 1. Range of shrimp (ADF&G 1978)
NAMEA. Cormon and Scientific Names: Northern pink shrimp
shrimp or
or deep sea
flexed shrimp
or spot prawn (Panda'lus
(Pdrnda'l'us hvEsTnoT[rsred (Pandalopus dispar
Brandt).
II. EXTENT TO WHICH SPECIES REPRESENTS GROUP
There are five important species of shrimp caught by cormercial
fisheries in Alaska, all of which belong to the family Panda'lidae.
Drawn (Pandalus borealis Kroyer); humpy
( panaat uTqo-ni uruffi on ) ; spot shrimp
pllitffi-s--ET6frd-t) ; coonstripe shrimp
EFand'-tT-s i destri pe shrimp or gi ant
421
I II. MNGEA. North America
The range of the northern pink shrimp extends from the Bering Sea
southward to the Columbia River mouth in hlashington (Rathjen and
Yesaki 1966).
Humpy shrimp have been found from the arctic coast of Alaska
southward to Puget Sound.
Coonstripe shrimp have been reported from the Bering Sea to the
Strait of Juan de Fuca.
The range of the spot shrimp extends from Unalaska Island, Alaska,
southward to San Diego, California.
Sidestripe shrimp are distributed from the Bering Sea, west of the
Pribi lof Islands, southward to Manhattan Beach, 0regon (ADF&G
1978).
Statewi de
Greatest concentrations of northern pink shrimp are located in
lower Cook Inlet, Kodiak, Shumagin Islands, and along the
southside of the Alaska Peninsula west to Unalaska Island. Pink
shrimp are also found along eastern Kenai Peninsula, Prince
William Sound, Yakutat Bay, throughout Southeast Alaska, and near
the Pribilof Islands in the eastern Bering Sea (ADF&G L978,
McCrary 1984).
Greatest concentrations of humpy shrimp are found off southeastern
Kodiak Island and the Shumagin Islands.
Coonstripe shrimp are primari'ly found in lower Cook Inlet, off
Kodiak Island, and among the Shumagin Islands.
Spot shrimp have been reported in lower Cook Inlet, off Kodiak
Island, and along the Alaska Peninsula.
Sidestripe shrimp concentrations have been located off Kodiak
Island, the Shumagin Islands, and in Lower Cook Inlet (ADF&G L978;
Merri tt, pers. comm. ) .
Regional Di stribution Sunmary
To-supplement the distribution information presented in the text,
a series of bluelined reference maps has been prepared for each
region. Most of the maps in this series are at 1:250'000 scale,
nui some are at 1:1.,000,000 scale. These maps are available for
review in ADF&G offices of the region or may be purchased from the
contract vendor responsible for their reproduction. In addition,
a set of colored 1:1,000,000-scale index maps of selected fish and
wildlife species has been prepared and may be found in the Atlas
that accompanies each regional guide.
1. Southwest. See the statewide summary above, and for more
Ae[l.TI ed- na rrati ve i nformati on , see vol ume I of the Al aska
Habitat Management Guide for the Southwest Region.
2. Southcentral. See the statewide summary above, and for more
ffiTl'ffiFrative information, see volume 2 of the Alaska
Habitat Management Guide for the Southcentral Region.
B.
c.
422
IV. PHYSICAL HABITAT REQUIREMENTSA. Water Qual ity
Distribution- of panda'lid shrimp is dependent upon the water's
temperature and salinity. Immature shrimp are to_1erant of a broad
range of temperature and sa1 inity and are often abundant in
retitive]y shallow depths, where these two parmeters are variable,
whereas older, sexual'ly mature shrimp prefer greater depths, where
these two parameters are more stable and less variable. With the
exception bf humpy shrimp, these pandalid species have been found
in a temperature -range of 7 to 11'C along the coast of British
Columbia'(Butler 1964). Humpy shrimp are apparently selective to
colder water temperatures. In laboratory studies' pink shrimp
were found to'have narrow thermal requirements for larval
production, with low temperatures (3-6oC) ge_nera'l1y more favorable
than high temperatures. Different thermal regimes resulted in
differenies in the time and duration of spawning and in the
abundance of egg-beari ng femal es. Larval production, I arval
survival, developmental and growth rates were enhanced by higher
(9"C) rearing temperatures, regardless of feeding levels. Size
inA viabiliti of newly hatched larvae are significant'ly influenced
by the therriral hi story of femal es duri ng the egg-bearing pgl!99
(a-t months). Low incubation (3"c) and higher rearing (9"c)
temperatures tended to increase 'larval and survival-growth rates
(Nuhes 1984). In the Bering Sea, concentrations of pink ll.,r!mpwere located at 0.5oC (Ivanov 1964b). Tolerance to sa'linity
appears to differ by species. The to'lerance of p'ink shrimp to
salinity in British Columbia waters has.be.en reported. to range
from 23.4 to 30.8 parts per thousand (o/oo) (Butler 1964). Butler
(1964) reported salinity tolerance ranges for coonstripe shrimp
from 25.9 to 30.6 o/oo, for spot shrimp from 26.4 to 30.8 o/oo,
and for sidestripe shrimp from 26.7 to 30.8 o/oo. During thq
winter, pink shrimp are generally absent from inner bay waters-of
less than 30 fathoms when bottom temperatures may be less than 2oC
and jce cover may be present. At the same time, where northern
shrimp are most concentrated, temperatures may range from I to 2"C
warmer than those of innermost bays of comparable depth (ADF&G
1e78).
ADF&G studies have shown that pandalid shrimp tend to be distri-
buted in one of two ways: 1) Younger age groups are located in
shallower areas, whereai older age gioups-are deeper; and 2) o'lder
age groups occur offshore, and younger age groups'are 'inshore.
ApparLntly, o'lder, sexually mature shrimp, especially. oviparous
fbmales, - prefer deeper water, where temperature an-d _sal inity
parameters are less variable. Younger shrimp, particu.'la11y those_
irior to first sexual maturity, are tolerant of a broader range of
salinities and temperature and are therefore often abundant in
nearshore or shal lower areas, where these two parameters are
general 1y more vari ab1e (ADF&G 1978) .
423
Water Quantity
The depth at which pandalid shrimp are found depends upon the
species and their stage of development. Shrimp larvae are found
in sha'llower waters than adults, ranging from about 5 to 35
fathoms in depth. From ages one to two years' pink shrimpjuveniles begin util izing bottom habitats of from 20 to 40
fathoms, though dense aggregations may be found at 50 to 70
fathoms. Adult pink shrimp inhabit water depths of from 10 to 350
fathoms (Rathjen and Yesaki 1966). The depth at which coonstripe
shrimp occur is similar to the depth range of humpy shrimp, whichis 3 to 100 fathoms (fox 1972). Spot shrimp have been found to
occur in depths from 2 to 266 fathoms (ibid.), and sidestripe
shrimp are commonly found in depths ranging from 20 to 351 fathoms
(Ronhol t 1963).
Substrate
Substrate preference appears to be species-specific. Pink and
sidestripe shrimp appear to prefer smooth, mud seabottoms. Humpy
shrimp primari'ly occur in areas with a substrate of smooth mud,
sand, or organic debris. Coonstripe shrimp prefer areas of smooth
mud, sand, or organic debris. Unlike the other species, spot
shrimp are primari]y found in rough, rocky areas (ADF&G 1978).
NUTRITIONAL REQUIREMENTSA. Preferred Foods
Adu'lt pandalid shrimp feed both by scavenging dead animal material
and by prey'ing on such living organisms as amphipods, euphausiids,
annel ids, and other shrimps ( ibid. ).
Feeding Locations
Larvae feed in the water co]umn. Juven'iles and adults are benthic
feeders.
Factors Limiting the Availability of Food
No information available.
Feeding Behavior
Adults are carnivorous bottom feeders (ibid.). Pink shrimp larvae
feeding rates increased with increasing temperatures. Among
starved larvae, higher temperatures lowered the threshold
concentrations of prey organisms required for successful first
feeding. The amount of food required by larvae to complete
development was sign'ificantly reduced at higher temperatures
(Nunes 1984).
VI. REPRODUCTIVE CHARACTERISTICSA. Breeding Habitat
The normal distribution of adults and breeding habitat covers a
wide range of depths varying by area and species. Breeding
habitat is not considered as vast'ly different from the normal
annual distribution of adults, except that depths occupied in fa'll
and winter tend to be deeper than in spring and summer for all
species. Commercial fisheries commonly operate on concentrationsof adults during the breeding season in areas and depths that
produce adults all year ((McCrary 1984).
B.
c.
V.
B.
c.
D.
424
B.
c.
D.
Breeding Seasonal ity
Timing bf spawning differs by geographica'l range for panda'lid
shrim[, where temferature is the controlling factor. For pink
shrimil at the northern extremities of its range.' _incubation.of
eqqs is lonqer because of an earlier spawning and later hatching
diie (Rasmuisen 1953, Al1en 1959). Genera'11y, eggs ripen in the
ovaries of the females. Breeding and egg deposition occur from
late September through mid November (ADF&G 1978).
Reproductive Behavior
Witnin SO hours after the female molts into breeding dress, the
male attaches a sperm mass to her underside between the last two
pairs of pereiopods (wa'lking legs) (Needler 1931). Fertilization
hnd ovipolit'ion occur as eggs are released from the oviducts and
onto thb sperm masses. Eggs then become attached to the forward
four pai ri of pleopods - (abdominal appendages) and abdominal
segments (ADF&G 1978).
Age at Sexual Maturity
The age at which sexual maturity is reached differs by species.and
by geographica'l location within a species. Pink shrimp f.ou.nd in
the- PriUitof areas of the Bering Sea and in the Kodiak and
Shumagin islands areas are estimated to reach maturity at 2.5
years (Ivanov 1964a, McCrary 1971). The same estimate is believed
1o hold true for sidestripe shrimp and, to a lesser extent, for
coonstripe and humpy shrimp in Kodiak and Shumagin islands waters.
Pink, humpy, coonstripe, and sidestripe shrimp species in
Southeast Alaska waters have been found to mature at 1.5 years
(McCrary 1971).
Pandalid shrimp may occur in one of three forms as they mature
sexual'ly. These include the hermophrod'itic male form, the
"primary female" form, or the "secondary -female" lorm.Hbrmaphioditic pandalid shrimp mature first as males, then later
in thejr life cycle transform into females. The age at which the
transition from male to female occurs also varies by species and
by geographical location within species. Individuals of a 9!ven
sbeCiei mature less rapidly as they inhabit waters in a co'lder
portion of the'ir range. Generally, mos.t shrimp function two years
hs a ma'le before becoming female (ADF&G 1978). In British
Co:lumbia, humpy shrimp mature as males during their first autumn
and again as'females at 1.5 years of age (But'ler 1964). Pink
shrimp, coonstripe shrimp, spot shrimp, . and sidestripe shrimp
general'ly mature as males at 1.5 years (Butler 1964, Dahlstrom
tgZO). An individual that has become female remains so throughoutits I ife.
"Primary females" are shrimp that mature directly as fema'les and
are never hermaphroditic. Though primary females have been
documented in pink shrimp populations off the coast of British
Columbia (Butler 1964), their occurrence in Alaskan waters is
believed to be rare (ibid.).
"secondary female" development entails the appearance of female
425
characteristics that are repressed before maturity is reached.
When the secondary female attains sexual maturity it remains
female for the rest of its life. Secondary females have been
documented in Southeast Alaska populations of pink, humpy, and
coonstripe shrimp but have not been documented in other Alaskan
waters (ADF&G 1978).E. Fecundity
Pandalid shrimp exhibit high fecundity. Eggs per clutch for pink
shrimp have been found to range in number from 478 to 2,II7. In
Southeast Alaska, the fecundity range for pink shrimp was from 809
to L,642; sidestripe shrimp ranged from 674 to 1,454; humpy shrimp
from 97L to 3,383; coonstripe shrimp from 1,083 to 4,583; spot
shrimp from 4,044 to 4,528. Fecund'ity is related to the size of
the shrimp, with larger shrimp producing more eggs (Alaska OCS
1e80).F. Frequency of Breeding
Shrimp usually mature sexually as males. After spawning one or
more times, they pass through a transitional phase and
subsequent'ly spawn as femal es. Transformation may occur so
rapidly that an individual spawning one year as a male will spawn
the following year as a female (Fox 1972).G. Incubatjon Period/Emergence
Females carry eggs for five to six months prior to hatching.
Hatching usually occurs from March through April for pink shrimp,
and for sidestripe shrimp it may extend into June or Ju1y. For
pink shrimp, the lengths of the spawning, carrying, and hatching
periods vary inversely with the water temperatures (Haynes and
Wigley 1969). Laboratory studies indicate that most eggs hatch at
night during periods of vigorous pleopod movement by the female.
Hatching of an entire clutch may require two days. Larvae are
planktonic for about two to three months; they pass through six
stages to become juveniles, at which time they become benthjc
(Berkeley 1930).
VII. MOVEMENTS ASSOCIATED hJITH LIFE FUNCTIONSA. LarvaeIn British Columbia, fresh'ly hatched larvae were found in the
vicinity of the spawned adults. The larvae then move to shallower
areas ranging from 9 to 64 m in depth, where they spend the first
summer ( ibid. ).B. Juveni I eIn British Columbia, juvenile p'ink, coonstripe, sidestrjpe, and
spot shrimp move to deeper water during their first winter to ioin
the adul t popul ati on ( i bi d. ) .C. Adul tPink shrimp have displayed fair'ly distinct seasonal
onshore-offshore migrations. They use shallow, nearshore, and
inner bays primarily from spring through fall. With the onset of
winter and colder temperatures 'in nearshore and inner bays, pink
shrimp migrate to warmer offshore areas (ADF&G 1978).
426
Female pink shrimp have been reported to move jnshore as their
eggs devel op i n i ate fal I and early wi nter (Haynes and hli g'ly
1i59). Pink' shrimp have also engaged in diel vertical migratio_ns,.
which appear to be related to feiding behavior because shrimp feed
main'ly on euphausiids and copepods, wh'ich make the same movements
(ADF&G 1e78).
Kachemak Bay studies have shown that pink shrimp leave the bottom
in late afiernoon or evening, returning to the same area about
dawn. The period of time that the shrimp remained away from the
sea bottom'varied directly with the season's number of hours of
darkness.
VIII. FACTORS INFLUENCING POPULATIONSA. Natural
Pandalid shrimp are subject to a high level of predation, both as
p1 anktoni c I arvae and as benthi c adul ts. Predators incl ude
Facific hake, Pacific cod, sablefish, lingcod, so1e, rockfish,
spring dogfish, skates, rays, Pacific halibut, salmon, and harbor
sbalsl Parasites and diiease also cause mortality of shrimp
populations. The black spot gi11 disease has been documented in
itri^imp from the Kodiak area. The gi1'l lamellae of the shrimp are
destrbyed, and a chi ti nous growth covers the damaged area 'creati-ng i "black spot" (Fox 1972, Yevich and Rinaldo 1971).
Spot shiimp in the.British Columbia area have been parasitized by
a rhizocephalen (sylon spp. ) (Butler 1970). -Bopyro'id isopods
(Bopyrus.ipp.) a'lslil-pE-ras'itize most species of pandalid shrimp
( Fox 1972) .It is apparent that the mechanism of stock recruitment for pink
shrimp in Alaskan waters is markedly influenced by temperature.
Temperature appears to control the reproductive pro-cess in pin!
shrimp, particularly during the period between egg formation and
egg development (Nunes 1984).B. Human-rel atedA summary of possible impacts from human-related activities
i ncl udes the fol 'lowi ng :o Alteration of preferred water temperatures, PH'
oxygen, and chemical compositiono Alteration of preferred substrate
" Alteration of intertidal areaso Increase in suspended organic or mineral materialo Reduction in food supply" Reduction in protective- cover (e.g., seaweed beds)o 0bstruction of migration routeso Shock waves in aquatic environmento Human harvest
(See Impacts of Land and Water Use of this series for additional
impacts information. )
di ssol ved
427
IX. LEGAL STATUSA. Managerial Authority
Shrimp populations are managed by the Alaska Department of Fish
and Game under policy regulations and management plans adopted by
the Alaska Board of Fisheries.
REFERENCES
ADF&G. 1978. Alaska's fisheries atlas. Vol. 2 [R.F. Mclean and
K.J. Delaney, comps.]. 43 pp. + maps.
Alaska OCS. 1980. Socioecomomic Studies Program, Western Alaska and Bering
- Norton petro'leum development scenarios: corrnercial fishing industry
analysis. Tech. Rept. 30. February 1980. Appendices A, B' and C.
Allen, J.A. 1959. 0n the biology of Pandalus borealis Kroyer, with
reference to a population off the Northumber'land land coast. J. Mar.
Biol. U.K., 38(1) :189-220.
Berkeley, A.A. 1930. The post-embryonic devel opment of the comnon
pandalids of British Columbia. Contrib. Can. Bio'1. 10(6):79-163.
Butler, T.H. 1964. Growth, reproduction, and distribution of pandalid
shrimps in British Columbia. J. Fish. Res. Bd. Can. 21(6):1,403-1,452.
. 1970. Synops i s of b'io1 ogi ca1 data on the prawn Panda'lgq
-.-@re.r* Brandi, i9s1. FAO Fish. Rept. 57(4):1,289-1,315.
Dahlstorm, W.A. 1970. Synopsis of biological data on the ocean shrimp
Pandalus jordani Rathbun, L902. FAO Fish. Rept. 57(4)2I,377-I,466.
Fox, l,|.W. 1972. Shrimp resources of the northeastern Pacific 0cean. Pages
313-337 in D.H. Rosenberg, ed. A review of the oceanography and
renewable-resources of the northern Gulf of Alaska. Alaska Institute
of Marine Science, Fairbanks.
Haynes, E.B., and R.L. Wi91y. 1969. Bio]ogy of the northern shrimp,
Pandalus borealis, in the Gulf of Maine. Trans. Am. Fish. Soc.
9'6-(-tl-: oo- 7T'.
Ivanov, B.G. 1964a. Results in the study of the biology and distributionof shrimps jn the Pribilof area of the Bering Sea. Trudy VNIR0'
vol.49. (Soviet Fisheries Investigations in the Northeast Pacific, USDI
trans'l . , 1968).
. 1964b. Bi ol ogy and di stri buti on of shrimps duri ng wi nterin the-TTf of Alaska and the Bering Sea. Trudy VNIRO, vol . 53. (Soviet
Fisheries Investigations in the Northeast Pac'ific, USDI transl., 1968).
428
McCrary, J.A. 1971. Pandalid shrimp studies proiect. Ann. tech. rept.,
Commercial Fisheries Research Development Act.
. 1984. Personal communication. Asst. Regional Supervisor.
-DF&G,
Div. commer. Fish., Kodiak.
Merritt, M. 1985. Personal communication. LCI Shellfish Research
Biologist, ADF&G, Div. Commer. Fish., Homer.
Needler, A.B. 1931. Mating and oviposition in
Field Nat. 45(5):107-8.
Pandalus danae.Canada
Nunes, P. 1984. Shrimp fishery research. Institute of Marine Science
Notes. Vol. 4. Univ. Alaska, Fairbanks. 4 pp.
Rasmussen, B. 1953. 0n the geographical variation in growth and sexual
development of the deep sea prawn (Pandalus borealis Kr.). Fish. Skr.
Havindersok, 10(3) : 160.
Rathjen, W.F., and M. Yesaki. 1966. Alaska shrimp explorations, 1962-64.
Comm. Fish. Rev. 28(4):1-14.
Ronholt, L.L. 1963. Distribution and relative abundance of commercial'ly
important pandalid shrimps in the northeastern Pacific 0cean. USFWS,
Spec. Sci. Rept. Fish. No. 449. 28 pp.
Yevich, P., and R.G. Rinaldo. I97L. Black spot gi11 disease of Pandalus
borealis. National Shellfish Association, 63rd Annual Convention.
IioT-T
429