HomeMy WebLinkAboutAPA1712November 1982
nt of Canada Gollvemement du Canada
and Oceans ~hes et Oceans
ALASKA RF:
U.s.DEP'
J.R.Brett,W.C.Clarke,and J.E.Shelbourn
.Department of Fisheries and Oceans
Fisheries Research Branch
Pacific Biological Station
Nanaimo,British Columbia V9H 5K6
Experiments on Thermal
Requirements.for G.rowthand
Food Conversion Efficiency of
Juvenile Chinook Salmon
Oncorhynchus tshawytscha
SH
223
.A3473
no.1127
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Canadian Technical Report of
Fisheries and Aquatic Sciences No.1127
November 1982
EXPERIMENTS ON THERMAL REQUIREMENTS FOR GROWTH AND
FOOD CONVERSION EFFICIENCY OF JUVENILE CHINOOK SALMON
Oncorhyncpus tshawytscha
by
J.R.Brett,W.C.Clarke,and J.E.Shelbourn
Department of Fisheries and Oceans
Fisheries Research Branch
·Pacific Biological Station
Nanaimo,British Co~umb,ia V9R 5K6
ARLIS
Alaska Resources
Library &lnfonnatlon ServIces
Anchorage,Alaska
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(c)Minister of Supply and Services Canada 1982
Cat.No.Fs 97-&/1127 ISSN 0706-6457
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ABSTRACT
J.R.Brett,W.C.Clarke,and J.E.She1bourn~1982.Expertments on thermal
requirements for growth and food conversion efficiency of juvenile
chinook salmon,Oncorhynchustshawytscha.Can.Tech.Rep.Fish.Aquat.
Sci.No.1127:iv +29 p.
Feeding and growth experiments on Nechako River and Big Qua1icum
River chinook juveniles were conducted for 28 days at temperatures from 16°to
24i>C (Nechako)and 14°to 25°C (Big Qualicum).On maximum daily ration,
optimum temperature for growth was approximately 19°C,above which feeding and
growth decreased particularly above 22°C.Mortalities reached 64%at 25°C,1n
agreement with earlier studies on lethal temperatures.In comparison with
Qua1icum chinooks,Nechako juveniles had a lower growth rate and food
conversion efficiency at all but the highest temperatures.
Measures of growth rate of natural populations in the NechakoRiver
showed that the rate corresponded to a feeding level of 60%of maximum daily
intake.The effect of such a reduced ration on the optimum temperature for
growth was deduced from a response model for sockeye salmon.This
showed that the expected optimum in nature for growth of Nechako River
chinooks would occur at 14.8°C.It was further deduced that sublethal growth
stress (20%reduction ingrowth from·optimum)would occur in the region of
18~19°C,and that for this feeding level no growb~would be possible at
21.4°C..
Key words:chinook salmon,temperature effect,growth rates,food conversion,
racial difference
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J.R.Brett,W.C.Clarke,and J.E.Shelbourn.1982.Experiments on thermal
requi rements for growth and food conversion effici ency of juvenile
chinook salmon,Oncorhynchus tshawytscha.Can.Tech.Rep.Fish.Aquat.
Sci.No.1127:iv +29 p.
Des experIences portant sur l'alimentation et Ia croissance ont ete
effectuees pendant 28 jours sur de jeunes saumons quinnats provenant des
ri vH~res Nechako et Big Qualicum a des temperatures variant respecti vement de
16 a 24°C (Nechako)et de 14 a 25°C (Big Qualicum).Moyennant une ration
quotidienne maximale,Ia temperature optimale de croissance des saumons etait
d'environ 19°C;a une temperature superieure,il y a eu une diminution de
1 'alimentation etde la croissance,particulierement au-dessusde 22°C.Le
taux de mortalite a atteint 64%a 25°C,ce qui concorde avec des etudes
anterieures portant sur les temperatures Ietales.A toutes les temperatures
sauf aux temperatures les plus elevees,Ie taux de croissance et l'efficacite
de la transformation de nourriture ont ete plus faibles chez les jeunes
saumons quinnats de la riviere Nechako que chez ceux de la riviere Qualicum.
Les mesures de taux de croissance des ,populations indigenes de la
rIVlere Nechako ont montre que celui-ci correspondait a une alimentation
equi valent a 60%de la ration quotidienne maximale.L'effet d'une rat ion
aussi reduite sur la temperature optimale de cro'issance a ete deduit a partir
des react ions enregistres chez Ie saumon rouge.Celles-ci ont mnt re que la
croissance,dans la nature,des saumons quinnats de Ia riviere Nechako devrait
etre optimale a 14,8°C.On en a conclu egalement que Ie niveau sous-letal de
croissance (baisse de 20%par rapport a l'optimum)serait atteint entre 18 et
19°C et que,a ce niveau d'alimentation,aucune croissance ne serait possible
a 21,4°C.
Mots-cles:Saumon quinnat,effet de Ia temperature,taux de croissance,
transformation de Ia nourriture,difference entre les races.
I.INTRODUCTION
Altered flQws and reduced discharge of water in the Nechako River,
British Columbia,have resulted in temperature elevations considerably above
normal,on occasion temporarily exceeding the lethal temperature for most
salmonids.The Aluminum Company of Canada (Alcan)holds the water licence for
developing hydro electric power in the region1 •Following the construction of
Kenney Dam,located at .the outlet of Natalkuz Lake,the headwaters of the
Nechako River were diverted westward to the Kemano generating station;spill
into the Nechako River was subject to full control by the operators.
In 1980,Alcan planned to reduce the spill discharge into the
Nechako River to a lower level in order to provide additional water for power
generation.This caused the Department of Fisheries and Oceans to become
concerned for the safety of resident juvenile chinook salmon (Oncorhynchus
tshawyts~ha)and migrant adult sockeye salmon (0.nerka).As a result,the
Department eriter¢d into discussions with Alcan in order to ensure that
discharge into the Nechako River was adequate to provide the salmon with
sufficient habitat and to protect them from excessively high water
temperatures.
The present study was undertaken to determine the effec ts of high
water temperature on growth and food conversion efficiency in juvenile chinook
salmon.Such information was required in addition to field observations in
order to assess the potential for sublethal stress imposed by reduced feeding
opportunity in warm water.Knowledge of temperature tolerance and sublethar
stress responses of chinook salmon is far from adequate to define safe thermal
limits.Indeed,the question of setting acceptable limits of natural
environmental factors like temperature,which can range from beneficial to
harmful effects,is a problematical one for precise definition.It is
therefore considered necessary at the outset to outline the plan of research
and its conceptual basis.
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II.RESEARCH PLAN
The criteria for setting safe limits of temperature for ·fish have
been considered by various authors (e.g.,Coutant 1977;Alabaster and Lloyd
1980;Elliott 1981).It has been noted,for instance,that no direct relation
exists between limits of distribution and upper lethal temperatures,the
latter usually being 4°-6°C above the limits of normal environmental
experience.One principle governing the criteria for determining tolerable
lIn 1950 the Government of British Columbia granted the right to Alcan to
divert a portion of the waters of the Nech~ko and Nanika rivers into the
Kemano River.I
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sublethal stress involves setting acceptable limits to the reduction of such
vital functions as swimming speed,metabolic scope,reproductive capacity,
growth,and food conversion efficiency.Because such information on chinook
salmon was almost entirely lacking,recommendations for safe limits of
temperature elevation were made initially by inference from knowledge of other
salmonids,particularly sockeye salmon (Brett 1969;Brett et ale 1969).In
general,abundance ,of sockeye juveniles is'curtailed at high environmental
temperatures where growth capacity and food conversion efficiency are reduced
by about one-fifth of that for the optimum temperature,according to the
feeding level or ration involved (Brett 1971).Because rising temperatures
place an increasing demand for energy to sustain metabolism,high feeding
rates are required to achieve good growth.Alternatively,if feeding
opportunity is restricted,a shift in the curve relating growth rate to
temperature occurs such that the optimum temperature for growth decreases.
This temperature-shunt phenomenon has been determined experimentally for
sockeye salmon (Fig.1),brown trout,yellow perch,and white suckers (Brett
et ale 1969;Kitchell and Stewart 1977;Elliott 1976;Koenst and Smith 1980).
The principle would apply in a similar fashion to starving fish which would
lose least weight when at the lowest tolerable temperature.The vertical
migration of lake-dwelling young sockeye into cold,deep water in summer has
been explained on the above energetic hypothesis,which is a further
illustration of improved growth at lower temperature when food is limiting
(Brett 1971;Biette and Geen 1980).
To determine the relation ofenvironntental temperature to the growth
capacity of young chinook salmon generally,and more particularly for the
level of feeding opportunity of the Nechako River population,a series of
steps involving laboratory experiments,field observations,and the
application of salmonid growth models was necessary.These entailed:
(1)Laboratory tests to establish the relation between temperature,
ration and growth --from which food conversion efficiency could also be
determined.The experiments involved local stocks of an appropriate river
size,and were conducted during the season of maximum environmental
temperature;
(2)Field studies of resident populations with representative
samples taken through the growing season to establish natural growth rates;
(3)The application of developed growth models (for coho and
chinook salmon)involving the parameters of ration,temperature,and fish
size,whiCh would permit determining the natural feeding rates of the juvenile
salmon for the particular river growth they achieved;
(4)Further,because of the'possibility of racial adaptation to the
thermal characteristics of a given watershed,some comparative studies on
chinook from an entirely different location were conducted.
In brief,the objective was to develop the 'curve that represented
the expected temperature-growth relations for the daily feeding level of the
natural population.From this,an informed estimate of limits of maximum
suitable environmental temperature could b~ascertained.
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III.MATERIALS AND METHODS
A.EXPERIMENTAL STUDIES
(1)Source and supply of fish
Chinook fry (n =280)were obtained in early May by seining 1n the
upper Nechako River.They were then shipped by air to the Pacific Biological
Station,NanairilQ,Be.C.On May 11,1981,a sample of 30 fry had a mean length
of 3.8S cm +0.37 SD and mean weight of 0.41 g +0.21 SD.The yolk was mostly
absorbed,all fry being "buttoned up"•.As indicated by the variance,
the range in length and weight was considerable,with some of the fry in
fairly poor condition bordering on pinheads.For experimental purposes,these
were subsequently weeded out,using only those that fell within +lSD of the
mean.
A comparable stock (n =440)from the Big Qualicum River hatchery
(Vancouver Island)was obtained in February,1981,as eggs.The hatched fry
were held at SoC.When sampled (n =30)on the same date as the Nechako fry
(May 11)they had a mean length of 3.88 cm +O.OS SD and a mean weight of
0.44 g +0.05 SD.Although of very similar-average size to the Nechako fry,
the Big-Qualicum fry were not fully buttoned-up and were of very uniform size
without any suggestion of being underfed.
(2)Culture and temperature history
The two stocks were raised on Oregon Moist Pellets (OMP)following
an initial appetite stimulant of brine shdmp.Feeding was three times per
day to near satiation •.Temperatures were maintained at approximately 10°C
until July 27,then raised to lSoC for 1 wk.At that time the fish were
transferred from the culture tanks to randomly assigned experimental tanks
(23)in which the temperatures were uniformly set at 20°C.A total of 30~ish
was weighed for each tank on August S,the start of the 28-day experiment.
The assigned experimental temperatures were then set for each tank on that
day.A sample of 2S fish from each of the river stocks was drawn from the
remaining reserves for determining initial dry weights.Final dry weights
were obtained for five fish from each of the 23 tanks following the last
weighing.The dry weight of the feed was also determined at the start and
finish of the experiments.
(3)Experimental design
Because or interest in the effects of warm water on the viability of
young salmon,experimental temperatures were chosen in the vicinity of the
expected optimum (between IS °and 20°C)rising to the limit of temperature
tolerance,in the vicinity of the upper lethal temperature at about 2SoC
(Brett 19S2).In essence the sockeye model (Fig.1)was used as the
prototype;however,the sensitivity of the present study was increased
considerably by testing at 1°C intervals instead of the wide-ranging SoC
intervals used previously for sockeye.
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With the lesser number of fry available for the Nechako stock,the
selected temperatures were:16°,19°,20°,21°,22°,23°,and 24°C,with
replicates performed at 20°,22°,and 24°C (total of 10 tanks).The Big
Qualicum stock was tested at a slightly wider range of temperatures:14°,
16°,18°,19°,20°,21°,22°,23°,24°,and 25°C,with replicates at 20°,22°,
and 24°C (total of 13 tanks).
Food was carefully weighed out each day,with the last feeding
continued until pellets were rejected.This was estimated (by counting
uneaten pellets)to be 5%in excess of satiation.In this way the maximum
daily ration (Rmax)was established.Food convkrsion efficiency was
determined by relating the total dry weight of food consumed to the dry weight
of growth achieved.In the few cases wh~re fish were injured or died between
weighings the assumed quantity of food eaten was prorated according to the
fraction of the period that the fish were alive.
B.FIELD STUDIES
Sampling of Fish
Juvenile chinooks were trapped or seined within 2 km of Irvine's
Lodge on the upper Nechako River approximately 10 km downstream from Cheslatta
Falls,the outfall of Murray Lake.The fish were either measured and weighed
immediately (trapped),or preserved in alcohol (seined)and weighed later.
Sample size was usually 50 fish,but on occasion only smaller
numbers were caught ranging down to 20 and 10.
Fishing began on March 22nd,1981,and continued on a daily basis
to May 8,1981.Late in May and early June some more samples were obtained
with a lapse until September when intensive sampling was renewed lasting
throughout the month.River temperatures were recorded at Irvine's Lodge.
RESULTS AND DISCUSSION
A.EXPERIMENTAL STUDIES
(1)Mortalities and,lethal temperature
Because of the limited number of Nechako chinooks available,only
the Big Qualicum juveniles were exposed to a temperature over 24°C.One tank
was assigned a temperature of 25°C.Over the 28-day period,the temperature
averaged 24.8°C +0.4 range.Although most fish appeared to be feeding at the
start (~hey had come from 20°C),within a week it was apparent that many had
ceased to feed.The first fish died on the 8th day,and fish continued to die
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sporadically reaching a cumulative total of 64%dead by the 28th day {Table 1,
Fig.2).Moribund fish were frequently bloated with water and usually
developed popeye.
"At 24°C,two Big Qualicum fish died on the 7th and 8th days without
any further loss.Since a mean growth rate of 1.6%wt/day characterized the
stock asa whole (2 Qualicum tanks and one Nechako tank,for a total n=75)no
direct lethal temperature significance was attached to these 2 cases.
Presumably,temperature had precipitated death from other causes.
The upper lethal temperature for juvenile chinook salmon (4.4 em,
1.03 g)from Dungeness River hatchery,Washington,U.S.A.was determined by
Brett (1952)to be 25.1 °c +0.1 SEe Fish were tested for a period of just
over 1 week.At 24.5°C the-resistance times were reported to exceed the
allotted test time i.e.,less than 50%death was recorded.At a test
temperature of 25.0°C the times to 50%death were determined as 7.4 days when
acclimated to 20°C,and 8.5 days when acclimated to 24°C.This illustrates
the fact that lethal temperatures are a sensitive physiological index.At the
critical thermal level a change of no more than 0.2°C can make the difference
between life and death.
The present experiments were not directed at determining lethal
temperatures,but the tank temperatures were elevated to border on the known
lethal level.From the results at 24.0°C and 24.8°C the temperature causing
50%death {LT50}in 28 days was 24.7 °C.There is insufficient evidence to
conclude that any significant difference in lethal temperature occurred
between any of the present stocks (Qualicum and Nechako)and the earlier tests
(Dungenessstock).In general,they confirm the previous findings as far as.
lethality is concerned.
(2)Growth rate x temperature {satiation ration}
As expected from results with other salmonids the gro\o1th rate rose
with temperature,passing through an optimum and then falling rapidly as the
lethal temperature was approached (Table 2;Fig.3 and 4).The apparent small
but positive growth rate at 24.8°C for Big Qualicum fish contains a bias in.lt
that the size achieved w~s that of the survivors -36%of the total.Loss of
weight-and subsequent death characterized the balance,meaning that if they
had lived the net result would have been negative growth.With this exception
and the loss of 2 fish at 24°C {Big Qualicum},the points represent the mean
growth rates over the period of 28 days.
A paired t-t;estfor treatments at comparable temperatures (IO)
indicated that the Big Qualicum fish grew significantly faster than the
Nechako fish{p <0.05).However,growth rate is known to be inversely
related to body size (Brett and Shelbourn 1975).If the growth rates were
adjusted to'account for the larger starting size of the Big Qualicum fish,the
mean difference between stocks would increase from an average of 0.15%/day to
O.59%/day,i.e.,a highly significant difference (see Fig.6,and later
discussion)•
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Fig •.3 and 4 illustrate the growth performance of each stock in
-relation to temperature.The lines represent nonlinear quadratic fits to the
data (Table 3).The standard deviations for the growth rates predicted by the
regression equations at 19°-23°C were 0.02%-0.03%/day;however the mean
difference in growth rate between all replicates was +0.11 %/day (Table 2).
The peak growth response on maximum ration was estimated to occur at 20.5°C
for the Big Qualicum stock <3.32%/day)and l8.9°C for the Nechako stock
(3.l5%/day).
Despite the lack of comparable temperature prec~s~on in earlier
experiments it is clear that chinooks have a higher optimum temperature,of
the order of 3-4°C above sockeye.This is undoubtedly in keeping with their
habit of occupying streams during the summer months,unlike sockeye which
daily descend to cool,deep waters during July and August.
(3)Feeding response
Daily records were kept of the appetite displayed by the fish in
each tank.At every temperature up to 22°C the response was at least good,
and mostly excellent.There was no noticeable change during the 4-week
period.At 23°C an initial good appetite fell off by the 3rd week to fair.
At 24°C,the appetite sequence was recorded as good +fair +poor +irregular
in the final week.For the highest temperature,at 25°C,an initial fair
response quickly fell off to poor and then toni!(with food rejected)by the
second week.This coincided with the start of mortalities.
(4)Food conversion efficiency
Food conversion efficiency in both stocks exhibited little change at
temperatures from l6-2l oc (Table 2;Fig.5).However,the difference between
the stocks was more pronounced than for growth rate.A paired t-test for the
ten comparable treatments demonstrated that the food conversion efficiency of
the Big Qualicum fish was significantly greater than for the Nechako fish
(P<O.OOl).In contrast to growth rate,food conversion efficiency is not
known to be size-dependent for juvenile fish.Hence,the difference in
starting size between stocks would not be expected to influence the
comparison.
Despite the broad dome shape of the relationship,optima were
computed from the nonlinear quadratic equations.These were 19.6°C (30.9%
conversion efficiency)for the Big Qualicum chinooks and 19.BoC (25.1%
conversion efficiency)for the Nechako chinooks.These optima differ from
those determined for growth rate by about 1°C.However,the curves are so
flat in this region that 1°C alters conversion efficiency by less than
0.2%--certainly not a biologically significant difference.
(5)Temperature relations for common s~ze
In order to further the growth comparison between the two stocks,
the specific growth rates (G)were corrected for initial size difference by
applying the general equation developed for salmonids:tn G =5.42-0.40 tnWt
it
where.
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(Brett and Shelbourn 1975).A common starting weight 'of 3.0 g was adopted.
It was assumed that the equation parameters applied equally at all
temperatures.The correction called for adding 0.12%wt/day to the observed
values for Big Qualicum and subtracting 0.32%wt/day for the Nechako growth
rates.The uncorrected average difference of O.lS%wt/day became 0.S9%/day.
It was also possible to'extend the curve relating G to temperature
by reference to studies performed by Banks (1971;Banks et a1.1971)and
modelled by Stauffer (1973).Results obtained for temperatures at 7.S 0,10°,
12.So and lSoC were applied to the Big Qualicum curve by prorating the values
starting at lSoC with an average G of 3.0S%wt/day (Fig.6).
Lacking the actual growth data for the full range of tolerable
temperatures (OO-2S0C),the above extension provides the best approximation of
how the dome-shaped curve would appear for this salmonid species.It is
deduced from the composite information that the optimum temperature for growth
of chinook juveniles occurs at about 19°C when on maximum ration.
(6)Stock difference
It is of interest that the greatest difference between the two
stocks of fish occurred in the region of the optimum temperature,with least
difference appearing in the proximity of the upper lethal temperature.This
suggests a selective mechanism operating to produce a genetic difference at
the point where physiological capacity to convert food and to grow is
greatest.Since abundance and distribution depend on being prosperous,
would appear that selection for suitability would occur at temperatures
viability was greatest.As stated,salmon do not normally occur in the
vicinity of their lethal temperature.
.Because the Big Qualicum fish were from hatchery stock,it could be
argued that selection for growth was occurring amongst those fish best able to
digest and use artificial food -Oregon moist pellets.However,successful
hatching and release of significant numbers of chinook juveniles did not occur
until19722 •With a maturation time of 3-S yr only three generations could
have reproduced in the time-span involved,hardly enough for any'significant
genetic change.
Alternatively,the consistently milder climate of the coast could
have brought about a shift of the temperature response system to be more
growth productive in the intermediate range of tolerable temperatures.
Whatever the cause,the significant fact is that the experiments clearly show
that the Nechako River chinooks possess no advantageous adaptation towards
survival in warmer waters than do chinooks from a coastal stream.
2First experimental releases of chinook fry (160,000)began in 1967,but
survival was poor and fertility low.Similar releases occurred in 1968 and
1970.In 1972 the first major successful release (300,000)was made (1971
brood),with precocious males returning in 1974.Since then ever-increasing
egg collection has grown to the point where over 3,000,000 are now cultured.
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B.FIELD STUDIES
(I)Growth of Nechako River juveniles
From the start of sampling on March 22nd to late May,the average
weight of fry (0.4 g)did not increase perceptibly.Apparently young fish
were arriving at the sampling point from upstream as a continuous production
of recently hatched fry without resident growth.Early in June,the weights
started to rise and were recorded in late summer and early fall as ranging
from 6 to 9 g (Fig.7).This is considered a resident population not subject
to major immigrations or emigrations.
From the growth curve presented,the average weight on June 1st was
0.5 g.The estimated average weight achieved by September 30th was 8.5 g.
The accompanying mean monthly temperatures are shown in Fig.7.These rose
from 4.0°C in April to peak at 17.7°C in August,falling back to l4.8°C in
September.
(2)Size prediction
Growth models for predicting expected size of hatchery fish have
been developed that take into account the initial size,the temperature
sequence,and the effect of level of feeding as a fraction of the maximum
ration -&max (McLean 1979).The most appropriate simulation model for
applicati~n to chinook salmon is that developed by Stauffer (1973)derived
from studies on coho and chinook salmon in Washington State hatcheries.
When applied to the Nechako chinook fry,starting on June 1st as
0.5 g fish,the prediction most closely approximating the attained growth by
September 30th corresponded to a ration equal to 60%of the maximum (Ro.6)'
Thus,for example,the weight predictions according to ration were as follows:
&max =17.4 g,Ro'8 =14.7 g;Ro'6 =8.6 g,RO'4 =3.2 g.The approximation
of the Ro'6 feeding level is very close to the 8.5 g average observed.
(3)Deduced thermal optimum
As described in the research plan,and illustrated in Fig.I,there
1S a particular growth rate x temperature curve for every level of ration up
to &max'Only the maximum curve was established for chinook juveniles,fed to
satiation.The consequence of reduced ration was modelled by applying the
proportional effect derived from the sockeye data.This is depicted in
Fig.8.
The deduced optimum temperature fora feeding level of 'Ro.6 occurred
at approximately 14.8°C with an expected growth rate of 1.8%!day.The
temperature for which RQ'6 would just provide for maintenance (Le.zero
growth)was estimated at 21.4°C.
Applying the safety criterion of accepting a 20%reduction in growth
rate (to 1.44%!day),the corresponding temperature providing for this growth
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occurs at 17.Boc.At 20°C the reduction in growth rate (0.7%/day)would be
approximately 50%of that provided by the Ro.6 optimum temperature.
CONCLUSIONS
(1)On a satiation ration,chinook salmon have an optimum temperature
for growth that is 3°t'o 4°C higher than that for sockeye salmon.It appears
to occur at about 19°C.
(2);In the region of the optimum temperature,Nechako chinook juveniles
show a si~nificantly reduced capacity to grow when compared with Big
Qualicum chinooks.
(3)Growth rates of summer populations of chinook juveniles in the
Nechako River indicate that the feeding level is 60%of that required to
satiate them.
(4)On such a ration,the optimum occurs at about 15°C;a temperature of
20°C would only permit 50%of the maximum growth capacity.At 21.4°C no
growth at all would occur.
ACKNOWLEDGMENTS
.__A
Field data on the Nechako River chinooks and the sample of wild fry
were kindly supplied by Mr.R.Russell of the Habitat Management Division,
Department of Fisheries and Oceans,Vancouver.The young chinook salmon from
Big Qualicum Hatchery were part of a stock held at low temperature by
Dr.D.F.Alderdice,Pacific Biological Station,Nanaimo.We are indebted to
the above for their contribution to the study.
REFERENCES
Alabast~r,J.S.,and R.Lloyd.1980.Water quality criteria for freshwater
fish •.Butterworths,London &Boston,297 p.
-10 -
Banks,J.L.1971.A temperature-time-weight equation for management of fall
chinook fingerlings in controlled environmental systems.Bureau of
Sports Fisheries and Wildlife,Tech.Rep.(Referred to in Stauffer
1973).
Banks,J.L.,L.G.Fowler,and J.W.Elliott.1971.Effects of rearing
temperature on growth,body form,and hematology of fall chinook
fingerlings.Prog.Fish.Cult.33:20-26.
Biette,R.M.,and G.H.Geen.1980.Growth of underyearling sockeye salmon
(Oncorhynchus nerka)under constant and cyclic temperatures in relation
to live zooplankton ration size.Can.J.Fish.Aquat.Sci.37:203-210.
Brett,J.R.1969.Temperature and fish.Chesapeake Science,10(3 &4}:
275-276.
Brett,J.R.,and J.E.Shelbourn.1975.Growth rate of young sockeye
salmon,Oncorhynchus nerka,in relation to fish size and ration level.
J.Fish.Res.Board Can.32:2103-2110.
Brett,J.R.1971.Energetic responses of salmon to temperature.A study of
some thermal relations in the physiology and freshwater ecology of
sockeye salmon (Oncorhynchus nerka).Am.Zool.11:99-113.
Temperature tolerance in young Pacific salmon,genus
J.Fish.Res.Bd.Can.9(6}:265-323.
Brett,J.R.1952.
Oncorhynchus.
Brett,J.R.,J.E.Shelbourn,and C.T.Shoop.'1969.Growth rate and body
composition of fingerling sockeye salmon,Oncorhynchus nerka,in relation
to temperature and ration sue.J.Fish.Res.Board Can.26:2363-2394.
Coutant,C.C.1977.Physiological considerations of future thermal
additions for aquatic life.251-266 p.In:Proc.of the World Conf.
"Towards a Plan of Action for Mankind",Vol.3,"Biological Balance and
Thermal Modifications".M.Marios [Ed.],Pengamon Press,New York,
251:266.
Elliot,J.M.1976.The energetics of feeding,metabolism and growth of
brown trout (Salmo trutta L.)in relation to body weight,water
temperature and ration size.J.Anim.Ecol.45:923-948.
Elliot,J.M.1981.Some aspects of thermal stress on freshwater teleosts.
p.209-245.In:Stress and Fish (Ed.A.~.Pickering)~cademic Press,
London and New York.
Kitchell,J.F.,and D.T.Stewart.1977.Applications of a bioenergetics
model to yellow perch (Perca flavescens)and walleye (Stizostedion
vitreum vitreum).J.'Fish.Res.Board Can.34:1922-1935.
Koenst,W.M.,and L.L.Smith Jr.1980.Factors influencing growth and
survival of White sucker,Catostomus commersoni.MS Dept.Ent.Fish.~
Wild.,Univ.Minnesota,St.Paul,Minn.,U.S.A.
McLean,W.E.1979.A rearing model for salmonids.M.Sc.thesis,Dept.
Interdiscip.Stud.,Univ •.British Columbia,Vancouver,B.C.120'p.
-11 -
Stauffer,G.'D.1973.A growth model for salmonids teared in hatchery
environments.Ph.D.thes is,Dept.Zoo 1.,Uni v.Wash.,Seat tIe,
Washington,U.S.A.213 p.
Schnute,J.
,fishery
,Pacific
1981.A manual for easy nonlinear parameter estimation in
research,with interactive microcomputer programs.Manuscript.
Biological Station,Nanaimo,B.C.
...
l I
-12 -
Table 1.Record of daily mortalities of juvenile chinook salmon from Big
Qua1icum River exposed to 24.8 +0.4°C range.
Time No.Cum.Dead
(days)dead dead (%)
8 1 1 4
9 1 2 8
11 1 3 12
18 1 4 16
21 1 5 20
24 1 6 24
25 3 ·9 36
28 7 16 64
-13 -
Tab Ie 2.weight,growth rate and food convers ion ef fic iency in reI at ion to
temperature for juvenile chinook salmon from Big Qualicum River stock (A)and
Nec:tlako River stock (B).Period of growth was 28 days,using 25 fish per
tank.Dry weights are the total gained for all fish per tank with the total
dry weight of food eaten.
Mean wet wt.
Assigned Mean Growth Dry wt.Dry wt.Conv.
temp.temp.Init.Final rate gain food effic.
(OC)(OC)(g) (g)%/day (g)(g)(%)
(A)
25 24.8 3.18 3.53*0.37**1.57 32.1 4.9
24 23.9 3.21 5.37 1.84 13.71 70.0 19.6
24 24.0 3.43 5.65 1.78 13 .63 69.4 19.6
23 23.0 3.16 6.50 2.58 22.04 85.3 25.8
22 22.0 3.34 8.26 3.23 32.84 101.4 32.4
22 21.8 3.34 7.98 3.11 30.97 100.8 30.7
21 20.9 3.35 8.82 3.46 36.51 116.0 32.7
20 19.9 3.24 8.32 3.37 33.91 108.3 31.3
20 19.9 3.14 7.79 3.25 31.04 107.5 28.9
19 19.0 3.30 7.65 3.00 29.04 100.5 28.9
18 18.1 3.29 8.56 3.42 35.18 111.5 31.6
16 16.0 3.27 7.31 2.87 26.97 88.6 30.4
14 13.9 3.35 7.71 2.98 29.10 90.5 32.2 •
(B)
24 23.9 2.09 3.48 1.82 9.00 58.1 15.5
24 23.7 2.48 3.82 1.54 8.68 65.2 13.3
23 23.0 2.49 4.78 2.33 15.11 83.2 18.2
22 21.9 2.56 5.62 2.81 20.43 90.2 22.6
22 21.8 2.48 5.63 2.93 23.43 91.7 25.6'"
21 21.0 2.30 5.60 3.18 22.03 93.7 23.5
20 20.0 2.46 5.84 3.09 22.56 94.9 23.8
20 19.9 2.64 6.22 3.06 23.36 85.1 27.5
19 19.0 2.28 5.50 3.14 21.49 90.6 23.7
16 15.9 2.31 5.44 3.06 20.96 90.3 23.2
*Mortality of 64%;weights are those of 9 surviving fish.
**Growth rate of surviving fish;not a true representation of total
sample,which would be characterized by negative growth.
-14 -
Table 3.Parameter values derived for fitting a nonlinear quadratic equation
to the specific growth rates <G)and food conversion efficiencies <CE)of Big
Qualicum and Nechako juvenile ch inook salmon in relat ion to temperature.Form
of equation:yo =bO +blXa +b2X2~.
Gamma bO bl b2 Alpha
Big Qualicum - G 0.98 0.83 0.94 -1.75 6.71
Nechako - G 2.65 0.87 0.81 -1.69 4.03
Big Qualicum -CE 0.12 0.97 0.03 -0.99 18.0
Nechako -CE 0.69 0.70 0.98 -1.64 4.95
Erratum p.14
For equation read
25201015
Temperature -°C
5o
-15 -
01--------------~---t""~~----±-~---+--1
Fig.1.The relation of growth rate (+2 SE)of sockeye salmon juveniles to
temperature for different levels of ration.Determinations computed in terms
of dry weights (%per day).Dotted line passes through the optimum
temperature and maximum growth rate for each ration level.Rmax =maximum
daily ration.From Brett et al.,1969.
-17 -
70
282420161284
•
I
/,.
•25°C /'-----------.•~24°CA-.----~-----...4 _
1/II.
Io-f"oo=;;,,;;:;;;,;:-==-=;o-:;;;,,;;:;;;,~IL.,--.--..-----,---r--.--..--.-----r--.----.:......,J
o
10
20
50 ----------------------------MEDIAN LETHAL --------------------
60
~
I 40
>-.....
-.J
<{
.....30a::o
~
TIME DAYS
Fig.2.Progress of mortality of chinook salmon juveniles from Big Qualicum
River when held for 28 days at approximately 24°and 2SoC.Actual mean
temperatures (+2 SD)were 24.0 +0.2°C and 24.8 +0.3°C.
-19 -
Fig.3.The relation of growth rate to temperature for juvenile Big Qua1icum
River chinook salmon fed to satiation.Initial mean weight =3.28 g.The
line was fitted by a nonlinear quadratic equation (Table 3).The arrow
indicates calculated optimum temperature.Circled point with arrow is based
on 36%9f fish that survived for 28 days at 24.8°C.The lethal temperature
limit is from Brett,1952.
l
I
,I,
.',I
I'II
!IIII
iii
Iii
"1
-21 -
4.0~·---'--------------------------..,
I
>-'<{
0 3.0r~-~
~°
1
IJ.1 2.0~a::
:r:
~
3:
0a::
(!)1.0
•
•
wa::
:::::>
I-«a::wa....
~w
I-
-J«
I
I-w
-J
262416182022
TEMPERATURE -°c
14
O+---,;---,--r-----r--r--r--~-~___r-_,_____.-_,.....-+_---r--J
12
Fig.4.Temperature relation for growth rate of juvenile Nechako River
chinook salmon fed to satiation.Initial mean weight =2.41 g.Fitted line
and arrow for optimum temperature calculated as stated in Fig.3..
·,
-23 -
BIG QUALICUM
35 1 0 0000
~0 ---0
°30 0 0
I •>-u ez25....----........w ",.--.......
u .""-;1 • •.,
LL /..,w
LL \0:::::>W 20 NECHAKO ,0)~«.,0::
Z W
0 CL
\.~CJ)w~15 \~w>e,z ...J
0 \«
u I
10 \~w
\...J
5 @
Ii
0 I
12 14 16 18 20 22 24 26
TEMPERATURE _oC
Fig.5.The relation of food conversion efficiency to temperature for chinook
salmon juveniles from Nechako and Big Qualicum rivers.The curves were fitted
by a nonlinear quadratic equation (see Table 3).Circled point is based on
the 36%of fish that survived for 28 days at 24.8°C.
·-
!!!
-25 -
4.0
W
0::
:::>
I-
<!
0::
W
0...
~w
I-
25
.$:
~<I••i)
··.1
15 20
TEMPERATURE -°c
10
3.5
as
~o
w 2.0....«a::
BIG QUALICUM
•If i)
~:"':
.,.•I)\
/•••••in/....$·...W/$...'...•./.;,/..~
//Y $
/NECHAKO ..
ABERNATHY //
~,//.
/
/
/
/I 1.5 /.
..../~/offi ID 1I/
Fig.6.The relation of growth rate to temperature for juvenile chinook
salmon fed to satiation.Growth rates adjusted to a common initial size of
3.0 g.Points for Abernathy derived from model of Stauffer (1973)based on
data of Banks (1971).They show the expected relative position for Big
Qualicum chinook salmon.Lines drawn by eye.
-27 -
•
u
o
1
W
0:::::>
I-«
0::
W
0...
~w
I-
4
16
10
6
14
8
12
18
•
•
o
o /••
-...........•-:.-..--"
2
7
8
6
CJl
5
I
t9 4
~
3 0
0+---r---r---r---r---r---r---r-----..---------..--------.--+2
o I 20 40 60 80 100 120 140 160 180 /200
APR.I TIME -DAYS SEPT.29
Fig.7.Mean wet weights (rt=50)of chinook salmon juveniles caught in the
Nechako River from March 22nd to September 29th,1981.Fish were not sampled
from June 10th to August 29th.Growth curve drawn by eye (broken line).Mean
monthly temperatures shown with solid line.
-29 -
DETERMINED
3·5 NECHAKO
CURVE SUBLETHAL
'-GROWTH>-<r 3.0 STRESS
0 f"-I7m!lll~·3
2.5 I~°
I
W 2.0I-
<r RO.60::,,,
r
,
I ,.-w
1.5 ,,0::I-,.-::J~.-I 1--
0
~.,,,,,,/<{
0::
,/0::
",;,WC>,,-PATH OF 0...1.0 ,,"-"~,,-
OPTIMUM TO w
I-
DEDUCED ---l
0.5 <{r
RIVER I-
W
RELATION ---l
0
10 12 14 16 \18 20 22 24 26
TEMPERATURE -°c
Fig.8.Growth rate ~temperature curves for Nechako River juvenile chinook
salmon.Top curve is from data presented in Fig.4 for fish fed a maximum
ration (Rmax )'Additional curves drawn for reduced daily rations (RO.8 and
Ro'6)according to the relation obtained for sockeye salmon juveniles (Fig.
1).Broken line indicates path of optimum temperature shifting to a lower
value as feeding level falls.The hatched bars indicate the temperature range
in which growth rate is reduced by 20%or more from that achieved at the
optimum temperature.