HomeMy WebLinkAboutAPA4162The Effect of the Hydro Dam
on the
Mayo River Fish Stocks
Report
by
R. E. Kende1
January 31, 1973
Department of the Environment
Fisheries Service
Northern Division
~ilhitehorse, Yukon Territory
1
INTRODUCTION
In 19.54 a hydro-power dam was placed on the Mayo River.
This structure poses a complete barrier to up stream :nri.gration of
fish from the Stewart River. Chinook salmon that had spawned above
the dam are now reported to spa~m in small numbers below, in .the
short section of rive~ between the Stewart River and the Dam.
The object of this study was to:
(1) assess the situation created by the dam in order
to insure the continued propagation of chinook
salrn6ri. ·
(2) acquire. information of other fish which inhabit
this stream.
2
METHODS
On June 13, 1972, the assessment program of the Mayo River
began, using the public campground as a base camp.
Species composition was determined with the use of a 50' x
8 1 small mesh seinet2-!" to 4-!" stretch mesh monofilament gill nets
and a 4 1 x 4' double throat fyke net. The gill nets were set in
various locations in the area of the public campground. The fyke
net was set in mid stream across from the campsight. Seineing was
done in various locations between the dam and the Stewart River and
also in the Mayo River above the dam, at Roop River and at Duncan
Creek. (Fig. #1)
Transportation to the various s&~pling locations was pro-
vided by truck, helicopter and a 12 foot rubber raft -powered with
a 9~· horsepower motor.
Species, length, weight and sex were recorded for most
samples collected.
Physical characteristics were quantified using standard
stream inventory techniques.
Disolved oxygen and pH were ~aKen using a Hach water
chemistry kit. Daily temperatures were recorded in °F using a
small pocket the~mometer.
Two local residents and the dam Supervisor were inter-
viewed in order to gain information about the area and about the
effects of the dam on the 1\iayo River.
3
Fig. #1 Study area
4 miles
~ -seineing sights
4
RESULTS
Species Composition
The species observed in the Mayo River between the dam and
the Stewart River are presented below.
Connnon Name" Scientific Name
l. chinook salmon (fry) Oncorhynchus tshawytscha
2. arctic grayling Thymallus arcticus
3. inconnu Stenodus leucichthys nelma
4. . . 1?-ke whitefish (humpback) Coregonus clupeaformis
5. round whitefish Proso~ium cylindraceum
6. lake trout Salvelinus namaycus~
7. longnose sucker Catostomus catostomus
8. northern pike Esox lucius --·
9. lake chub Couesius plumbeus
10. slimy sculpin Cottus cognatus
The longnose sucker was the most abundant fish taken in
the gill nets. Many were mat11!'8 and in spawning colours. Grayling
and round whitefish were secondary in abundance.
Seineing produced large numbers of immature ~rayling and
round whitefish as v.Jell ·as numerous chinook salmon fry. Fig. #2
gives the length frequency distribution of 36 chinook fry captured
by seine during the study period.
The length range of im~ature grayling taken wa~ 75 mm to
158 mm with the heaviest concentration between 81 and 90 mm.
Lengths and weights of all fish sampled can be found in
Fig. 3.
The results of the scale readings will be added after they
have been processed at regional office.
5
Fig. #2 LENGTH FREQUENCE -JULY 1972
FOR CHINOOK FRY
10 n"' :36
9
8 •
7 0
6 • ~
Q)
~5
:z:
4 •
3 •
2 • • •
1 • •
33 34 35 3 37 3 39 40 41 42
Length in nnn
Phvsical Characteristics
The physical characteristics observed were similar to those
by C. Walker and G. Jones in the report Shut-Off of Discharge at Mayo
River Powerhouse, 1972.
Comnensing at the mouth:
0.0 -3.0 miles -generally riffle-pool
80% coarse material with some fines; silt and sand.
3.0 -·4.5 miJ.es -slightly steeper gradient
90% coarse material.
4.5 -5.5 miles -canyon area, bedrocks and boulder
steepest gradient of stream.
5.5 -7.0 miles -90% boulder, lesser gradient than canyon area but
greater than lower 4.5 miles.
Daily discharges varied according to the needs of the
powerhouse.· A record of daily discharges is available from Northern
Canada Power Corrunission at Mayo.
Colour varied from clear to dark brown and debris load
ranged from slight to heavy also depending on the discharge.
Water temperatures during the study period ranged from the low
to mid 40°1 s at night, to highs in the low 60°1 s during late after-
noon.
6
Dissolved oxygen concentrations remained between 10 and
ll ppm and a pH of 7.5 was recorded.
Interviews
The dam supervisor, Mr •. J. ?odhora, was interviewed on June
13, 1972. At this time it was ..Learned that large daily fluctuations
in discharge through the&m and powerhouse occurred. It was also
learned that in the summer of each year the flow was cut off com-
pletely in order to inspect the facility. It was requested at this
time that our office-in Ahitehorse be notified prior to any future
shut downs. These conditions were reported to our office and the
regional office was notified so that further action could be taken.
Mr. A.· Pelland, a long time resident of Mayo and cormnercial
fish.errnan, provided the following information about the area before
dam construction. According to his recollection, chinook salmon were
sighted in the Mayo River as far up as Mayo Lake as well as in Duncan
and Davidson Creeks, both being tributaries to the Mayo River. He
estimated the run of chum salmon to be in the thousands but declined
to estimate the numbers of chinooks. He also reported a drastic
increase in the pike populations in the Mayo area since the dam's
construction.
From a conversation held with Mr. C ~~'food, a local resident,
it was learned that during dam shut downs local residents were known
to catch stranded fish by methods which ranged from clubbing in the -
pools to jumping off the bridge after them. He also stated that shut
downs had Q_c.s;urred ,d:uri.qg~.::.!'~~Il!Qf! __ !U?§.Wll.:i,ng _ _,and was concerned about the
effects of this practice. ~ C-r~J& :.luJ,<J ... ;-_,,. _.
Other Areas Examined
July 5, 1972.
Mayo River -below Mayo Lake to Minto Bridge.
width -100 to 150 feet.
L
Composition -boulder 60%; coarse 3Cf~, fine 9~; sand and
silt 1%.
0 Temperature -59 F at 10 am.
Colour -clear up to reservoir.
Discharge -844 cfs.
Fish observed -grayling, longnose suckers and sculpins.
Obstructions -control dam, complete barrier~' c.~-r·?'o.'"" 1<t~><J>f.
7
July 8, 1972
Duncan Creek -tributary to Mayo River
Width -40 -50 feet
Composition--boulder 90%, coarse 9%, fines 1%.
Temperature -49°F at 1:00 pm.
Colour -clear.
Discharge -210 cfs.
Fish observed -grayling.
Obstructions ·-none.
June 30, 1972.
Roop Creek -tributary of :Mayo Lake - 3 miles upstream.
~'/idth -75-100 feete
Composition -boulder lry~, coarse 50%, fine 30%, silt and
sand 10%.
Temperature-51°F at 1:00pm.
Colour -clear.
Discharge 380 cfs.
Fish observed -Sculpin and grayling.
Obstructions -many dead falls but no major obstructions.
Salmon Counts
On August 26, 1972, the Mayo River was flown by helicopter
to count chinook salmon. At this time 20 dead chinook salmon were
sighted but no live were observed.
October 8, 1972, the Hayo River was again fl0\'1.'11 by heli-
copter to count chum salrnon. No chums were observed at this time.
8
DISCUSSION
This study has shown that the short section of river be-
tween the hydro da~ and the Stewart River is frequented by at least
9 species of fresh water fish and l species of Pacific Salmon. Chum
salmon, as well as chinook salmon have been reported to spawn in this
river but were not observed during the study period. The river also
appears to be used as a spawr1ing grounds for chinook salmon, arctic
grayling, northern pike, round whitefish and longnose suckers and is
used extensively as a rear.ing area for their fry.
From conversations with local residents, it was learned
that the chinook salmon spawning population has been reduced to a.
mere fragment of the original stocks by the dam's const~ction) and
that.damage to the total fish stocks is a continuing process due to
Gd'rafic changes in daily discharges through the river bed. During
the .study period the daily silt and debris load, due to soil erosion,
that accompanied the fluctuations in discharge posed a threat to in-
cubating eggs in the lower one third of the river. (Fig.#4) The
annual shut off of discharge at the powerhouse also sets the scene
for a potential disaster, since fish become stranded in pools and
overheating of the water may cause death to less heat tolerant species
such as arctic graying and whitefish. It also leaves the fish more
vulnerable to abuse by humans and predators at this time.
It is hoped that through continued study of this area and
through co-operation of Northern Canada Power Commission in implement-
ing the recommendations made by the Fisheries Service that these sit-
uations can be rectified to ensure the well being of the native fish
stocks.
9
Fig. # 3
METHOD
DATE AND )'fEIGHT LEtGTH OF
LOCATION SPECIES IN gm. IN mm. SEX HATURITY SCALES CAPTURE
1 June 13, 1972 Round 12.5 112 ? IM Seine
Ca;11psite ~'fhi tefish
2 II II Round 18.5 132 ? IM II
ltfhi tefi sh
3 II II Round 12.4 120 ? IM II
Whitefish
4 II II Grayling 36.7 155 ? IM II
5 II II Grayling 5.1 83 ? IM II
6 II II Grayling 28.0 141 ? IM II
7 II II Grayling -16.0 123 ? IM " 8 II II Grayling 17.0 158 ? IM II
9 II II Grayling 22.9 136 ? IM II
10 II II Grayling 25.5 145 ? IM II
11 II II Chinook fry .6 39 ? IM II
12 II II Pike 85.3 220 ? D1: Bl -1&2 Gillnet
13 II II Bur bot 20.7 150 ·? IM Fyke ne
14 II II Pike 859.1 502 M M-ripe Bl -3&4 Fyke ne·
15 June 14, 1972
Across from Chinook fry 0.7 42 ? IM Seine
Campsite
16 II II Chinook fry 0.5 37 ? IM II
17 II II Grayling 7.1 93 ? IM II
18 rr .II Grayling 6.2 82 ? IM II
19 II II Grayling 12.1 105 ? IM II
20 II II Grayling 6.3 84 ? IN " 21 II II Grayling 6.3 80 ? IM II
22 II II Grayling 6.5 87 ? IM II
23 II II Grayling 6.5 85 ? IM II
24 II II Grayling 6.0 84 ? D'I II
25 II II Grayling 5.9 76 ? IM II
26 rr II Grayling 7.1 90 ? HI II
27 II II Grayling 3.7 75 ? D4 II
28 II II Round 8.1 105 ? IM II
'vfuitefish
29 II II Round 14.0 122 ? IM II
V'lhitefish
30 II II Round 5.8 92 ? IM II
vihitefish
31 June 15, 1972 Burbot 5.5 100 ? IM Fyke net
Campsite
32 II II Bur bot 4.4 92 ? IM Fyke net
33 II II Lake Chub 1.5 57 ? IM Fyke net
34 Bridge Inconnu 570 I"' r1 Bl -5&6 G~l~netc
35 " Longnose 507.0 360 F H-ripe 2 me ....
II
Sucker
36 II Longnose 336.0 325 M M-ripe !I
Sucker
37 II Longnose 618.0 413 F M-ripe II
Sucker
38. June 16, 1972 Grayling 1o~o 100 ? IM Seine
l mile dovm-
stream from
Campsite
39 II !I Grayling 6.0 86 ? I£1 II
.J..V .l.u..JJ.!•VU
-DATE AND ~!EIGHT LENGTH OF'
LOCA}.'ION SPECIES IN gm. IN mm. SEX i"L!\.TURITY SCAL&S CAPTURE -
4C B:r:~..~ge Longnose 387.5 361 M M-:ripe Gillnet
June 16, 1973 Suckers 2t"
41 II Round 336.0 351 F M Bl -7&8 II
vfuitefish
42 II Grayling 164.0 245 F M-spawned out Bl -9&10 II
43 II Grayling 210.0 273 F M Bl 11&12 II
44 II Grayling 191.5 267 M M-spawned out Bl 13&14 II
45 July 18, 1972 Inconnu 433.0 335 ? M B2 -1&2 Seine
46 II II Grayling 325.0 310 ? M B2 3&4 II
47 II II Humpback 614.1 370 ? }1 B2 -5&6 II
Whitefish
48 II II Lake trout 5.4 80 ? IM II
49 II " Lake trout 5.2 77 ? IM II
50 II II Lake trout 5.J 78 ? IM II
'51 II II Lake trout 5.0 77 ? IM II
52 II II Chinook fry 0.9 40 ? IM II
53 " II Chinook fry 0.8 39 ? IM II
54 II II Grayling 425.2 350 M M B2 -7&8 II
55 II II Gray: ling 242.0 280 ? M B2 -9&10 II
56 II II Grayling 6.3 90 ? IM ?
57 II II Lake trout 2.3 55 ? IM
58 II II Lake trout 3.3 63 ? IM
59 II II Chinook fry 0.6 38 ? IM
60 II II Chinook fry 0.5 36 ? IM
61 II II Chinook fry 0.5 37 ? IM
62 II II Whitefish(?) 3.7 65 ? IM
63 II ,, II II 1.4 50 ? IM
64 II• II Chinook fry 11 t. l'l ? IIvl VoV Lj..<:.
65 II II Chinook fry 0.7 44 ? IM
66 II II Chinook fry 0.8 43 ? IM
67 II II Chinook fry 0.6 39 ? IM
68 II II Chinook fry 0.7 42 ? IM
69 II II Chinook fry 0.4 38 ? IM
70 II II Chinook fry 0.5 41 ? IM ...
71 II II Chinook fry 0.5 41 ? Ir1
72 II II Chinook fry 0.5 38 ? IM
73 II II .Chinook fry 0.3 36 ? IM
74 II II 'Whitefish (?) 2.9 76 ? IM
75 II II Chinook fry 50 1 seir
76 II II Humpback 439.5 340 M M B2 -11&12 ?
Whitefish
77 II II Grayling 184.0 265 M IM B2 -13&14 Seine
78 II II Chinook fry 1.5 52 ? ?
79 II II Chinook fry 1.5 50 ? ?
90 II II Chinook fry 1.1 45 ? ?
31 II II Chinook fry 1.0 45 ? ?
11
Fig . # 4 Bank erosion at Campground on Mayo River
J
Fig. # 5 Hayo River near Campground
I~
F . # / l.g. ,· 0 Area below Powerhouse where chinook are reported to spav-m.
Fig. # 7 Dry channel between Dam and Powerhouse
13
RECOMMENDATIONS
(1) The incomplete nature of findings from this years work
suggests that further studies t~ undertaken in the Mayo area.
(2) Some time should be spent in the area soon after break-up
in order to assess the chinook srnolt migration. Sca..le samples should be
taken in order to establish an age index for these juvenile fish.
(3) Efforts should be made to locate important spawning grounds
for chinook salmon, chum salmon, grayling, suckers and round whitefish.
(4) Spawning counts of chinook and chum salmon should be carried
out in the Mayo River below the dam.
(5) The operation of the N.C.P.C. Dam should be observed in
order to prevent actions with potentially harmful results, ie. shut off
of fl~s and continual fluctuation· of discharge.
14
Acknowledgement
Thanks is extended to the following people for their valuable
assistance in collection of data for this report: D. Kaines, D. Russell,
B. Smith and E. Smyth •.
Yukon Archi..-es
Whitehorse
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PA.M \-'\1 'S-OL\l 14