Alternative models of climatic effects on sockeye salmon, Oncorhynchus nerka, productivity in Bristol Bay, Alaska, and the Fraser River, British Columbia

The objective of this study was to combine radio telemetry with individual thermal loggers to assess the extent to which adult migrating sockeye salmon ( Oncorhynchus nerka (Walbaum in Artedi, 1792)) behaviourally thermoregulate during their migration through the Fraser River mainstem, British Columbia. The Fraser mainstem represents a region of the migration route that contains some of the highest mean temperatures encountered by sockeye salmon during their life history. We found that throughout the study area, individual sockeye salmon body temperatures occasionally deviated from ambient temperatures (ΔT), yet individuals maintained a ΔT of –1 °C or cooler for only 5% of their migration through the study region. There were moderate mean deviations of ΔT in two segments that are known to contain thermally stratified waters. In one of the study segments with the greatest ΔT, mean body temperatures decreased as river temperatures increased and ΔT became increasingly positive with higher river discharge rates, but these relationships were not observed in any of the other study segments. No relationship existed between ΔT and migration rate. While periodic associations with cool water were evident, mean body temperatures were not significantly different than mean river temperatures throughout the lower Fraser mainstem. This finding raises further conservation concerns for vulnerable Fraser River sockeye stocks that are predicted to encounter increasing peak summer river temperatures in the coming decades.

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Estimating Stock Composition of Migrating Juvenile Fraser River (British Columbia) Sockeye Salmon, Oncorhynchus nerka, Using Parasites as Natural Tags

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f88-071 ◽

1988 ◽

Vol 45 (4) ◽

pp. 586-591 ◽

Cited By ~ 15

Author(s):

R. E. Bailey ◽

L. Margolis ◽

C. Groot

Keyword(s):

British Columbia ◽

Maximum Likelihood ◽

Sockeye Salmon ◽

Oncorhynchus Nerka ◽

Fraser River ◽

Dominant Group ◽

Strait Of Georgia ◽

Natural Tags ◽

Lake Washington ◽

The Individual

Simulated mixtures of juvenile sockeye salmon (Oncorhynchus nerka) were constructed using parasite data to represent proportionally the major component stocks of Fraser River and Lake Washington sockeye migrating within the Strait of Georgia, British Columbia, in 1982–84. Samples of migrating juveniles were also collected from Bedwell Harbour, South Pender Island, British Columbia, each year and analyzed for parasites and stock composition. The compositions of simulated and sample mixtures were estimated using a maximum likelihood stock composition model. Simulated mixture compositions were accurately estimated for most stocks for all year-classes. When significant misassignment occurred between stocks, the stocks were analyzed as a complex using the allocate-sum procedure. Sample mixture estimates correctly identified the dominant stock for each year-class, although for 1984 the dominant group was determined as a complex of three stocks because the individual stocks were not distinguishable. The results indicate that it is feasible to use parasites as natural tags to estimate stock compositions of migrating juvenile sockeye salmon in the Strait of Georgia.

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Patterns of Interannual Variation in Age at Maturity of Sockeye Salmon (Oncorhynchus nerka) in Alaska and British Columbia

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f85-200 ◽

1985 ◽

Vol 42 (10) ◽

pp. 1595-1607 ◽

Cited By ~ 16

Author(s):

Randall M. Peterman

Keyword(s):

British Columbia ◽

Life Histories ◽

Sockeye Salmon ◽

Oncorhynchus Nerka ◽

Comparative Approach ◽

Age At Maturity ◽

Bristol Bay ◽

Freshwater Environment ◽

Marine Life ◽

Alternative Hypotheses

Interannual variations in mean age of maturity tend to be positively correlated among 10 stocks of sockeye salmon (Oncorhynchus nerka) which spawn in rivers emptying into Bristol Bay, Alaska. Taking a comparative approach, I utilized data from British Columbia and Alaska sockeye stocks with different life histories to test alternative hypotheses about sources of these variations in mean age at maturity. The hypotheses included freshwater environment, marine environment, and parental influences. Freshwater hypotheses were rejected and while some parental effects do exist, they are small compared with the effect of events in early marine life. Early marine growth rate data do not exist for these stocks but evidence from five other sockeye stocks shows that fast growth during this period tends to lead to earlier age at maturity.

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Cross Correlations Between Reconstructed Ocean Abundances of Bristol Bay and British Columbia Sockeye Salmon (Oncorhynchus nerka)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f84-222 ◽

1984 ◽

Vol 41 (12) ◽

pp. 1814-1824 ◽

Cited By ~ 5

Author(s):

Randall M. Peterman ◽

Fred Y. C Wong

Keyword(s):

British Columbia ◽

Sockeye Salmon ◽

Population Analysis ◽

Oncorhynchus Nerka ◽

Survival Rates ◽

Gulf Of Alaska ◽

Time Lags ◽

Bristol Bay ◽

Reconstruction Methods ◽

Cross Correlations

Anecdotal reports of a tendency for British Columbia sockeye salmon (Oncorhynchus nerka) to be low when Bristol Bay, Alaska, returns are high prompted a reconstruction of minimum abundances of sockeye resident in the Gulf of Alaska each year from the early 1950s to mid-1970s. This backwards reconstruction using Fry's virtual population analysis was done by using catch, escapement, and age structure data for each area in British Columbia and Bristol Bay. Use of more sophisticated backwards reconstruction methods was precluded by lack of age-specific annual survival rates by stock. Ocean abundances of British Columbia and Bristol Bay sockeye show significant autocorrelations at periods consistent with the cyclic dominant patterns of their largest stocks. Cross correlations at lag 0 between ocean abundances of various ages of fish from these two regions show one case of a significant inverse relation in abundances. In addition, there are significant cross correlations between British Columbia and Bristol Bay ocean abundances at various time lags, showing that cycles in their abundances are out of synchrony. This lack of synchrony persisted longer than would be expected from cyclic dominance patterns and age at maturity of British Columbia and Bristol Bay sockeye, and several alternative explanations of this asynchrony are discussed.

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Environmental and Parental Influences on Age at Maturity in Sockeye Salmon (Oncorhynchus nerka) from the Fraser River, British Columbia

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f86-034 ◽

1986 ◽

Vol 43 (2) ◽

pp. 269-274 ◽

Cited By ~ 5

Author(s):

Randall M. Peterman ◽

Michael J. Bradford ◽

Judith L. Anderson

Keyword(s):

British Columbia ◽

Age Structure ◽

Sockeye Salmon ◽

Oncorhynchus Nerka ◽

Data Series ◽

Fraser River ◽

Age At Maturity ◽

Long Term Effects ◽

River Population ◽

The Mean

Commercial fisheries possess the potential for applying strong selection on size or age at maturity in the populations they exploit. It is therefore important to know the extent to which these traits are inherited. We examined regressions of the mean age at maturity of cohorts of offspring on the mean ages of the female and male spawners which produced them for four populations of sockeye salmon (Oncorhynchus nerka) from the Fraser River, British Columbia. Unlike previous researchers, we found that neither genetic nor maternal effects are important, relative to environmental variables, in influencing year-to-year variation in age at maturity in these stocks. The differences between our findings and earlier ones are due to a longer data series and more complete population statistics than were available previously. We further analyzed the age structure of the Adams River population, which has a cyclic pattern of abundance. Fluctuating population density appeared to account for variation in age structure among cycle years in the Adams stock. We concluded that serious concerns about the long-term effects of size-selective fishing on mean age at maturity are probably not warranted for Fraser River sockeye.

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Variants of Lactate Dehydrogenase Isozymes in Sera of Sockeye Salmon (Oncorhynchus nerka)

Journal of the Fisheries Research Board of Canada ◽

10.1139/f69-002 ◽

1969 ◽

Vol 26 (1) ◽

pp. 15-19 ◽

Cited By ~ 20

Author(s):

H. O. Hodgins ◽

W. E. Ames ◽

F. M. Utter

Keyword(s):

British Columbia ◽

Lactate Dehydrogenase ◽

Sockeye Salmon ◽

Oncorhynchus Nerka ◽

Gulf Of Alaska ◽

Bristol Bay ◽

Lactate Dehydrogenase Isozymes ◽

Skeena River ◽

Total Body ◽

Ldh Isozymes

Three phenotypes of lactate dehydrogenase (LDH) isozymes were found in sera of sockeye salmon (Oncorhynchus nerka), presumably representing B′B′, B′B, and BB genotypes. No association was obvious between LDH phenotype of sera and sex or total body length.Of 1006 sera from Asian, Bristol Bay, and Gulf of Alaska stocks, 826 were B′B′ and 180 were B′B or BB. Of 591 sera from Washington and British Columbia stocks, 589 were B′B′ and 2 were B′B; both of the B-allele phenotypes were found in fish captured at the Skeena River in northern British Columbia. These findings suggested that LDH isozymes should be useful in studies on ocean distribution of sockeye salmon and in characterizing certain Asian and Alaskan sockeye salmon populations.

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Precocial maturation of male sockeye salmon in the Fraser River, British Columbia, and its relationship to growth and year-class strength

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f00-202 ◽

2000 ◽

Vol 57 (11) ◽

pp. 2248-2257 ◽

Cited By ~ 7

Author(s):

M C Healey ◽

M A Henderson ◽

Ingrid Burgetz

Keyword(s):

British Columbia ◽

Age Structure ◽

Sockeye Salmon ◽

Historical Data ◽

Oncorhynchus Nerka ◽

Fraser River ◽

The West ◽

Migration Distance ◽

Male Brood ◽

Class Strength

We analyzed historical data on the age structure and abundance of males in 22 populations of sockeye salmon (Oncorhynchus nerka) in the Fraser River, British Columbia, to determine geographical and temporal patterns of precocial maturation, its relationship with growth and maturation at other ages, and the value of precocial males as indicators of year-class strength. Most Fraser sockeye males spend two winters at sea before maturing at 3-5 years of age. Precocial males return to spawn at 2, 3, or 4 years of age (ages 0.1, 1.1, and 2.1) and comprised <1 to >33% of male brood year returns among populations. Precocity was lowest among populations that spawned far upstream and highest among populations spawning to the west of the main Fraser River and was not correlated with migration distance. Precocial maturation was related to growth during the second summer in the ocean to brood line and to brood line abundance. The combination of brood line, abundance, and size of precocial males accounted for more than 75% of the variation in total returns in four populations, suggesting that these variables might be used to predict abundance 1 year in advance.

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Patterns of covariation in survival rates of British Columbian and Alaskan sockeye salmon (Oncorhynchus nerka) stocks

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f98-179 ◽

1998 ◽

Vol 55 (11) ◽

pp. 2503-2517 ◽

Cited By ~ 81

Author(s):

Randall M Peterman ◽

Brian J Pyper ◽

Michael F Lapointe ◽

Milo D Adkison ◽

Carl J Walters

Keyword(s):

Survival Rate ◽

Sockeye Salmon ◽

Spatial Scales ◽

Oncorhynchus Nerka ◽

Survival Rates ◽

Ocean Basin ◽

Similar Response ◽

Fraser River ◽

Bristol Bay ◽

Basin Scale

We used a multi-stock comparison to identify spatial and temporal characteristics of environmentally driven sources of variability across four decades in the productivity of 29 sockeye salmon (Oncorhynchus nerka) stocks from British Columbia (B.C.) and Alaska. We examined patterns of covariation among indices of survival rate (residuals from the best-fit stock-recruitment curve) and found positive covariation among Fraser River sockeye stocks (southern B.C.) and, to a greater extent, among Bristol Bay stocks (western Alaska) but no evidence of covariation between these two regions or with stocks of other regions in B.C. and Alaska. This indicates that important environmental processes affecting variation in sockeye survival rate from spawners to recruits operate at regional spatial scales, rather than at the larger, ocean-basin scale. The observed covariation in survival rates of Bristol Bay stocks appears to be due to a combination of both freshwater and, to a greater degree, marine processes. Bristol Bay sockeye stocks showed a dramatic and persistent increase in survival rates coinciding with the abrupt changes in the North Pacific environment in the mid-1970s; however, there was little evidence of a similar response for Fraser River stocks.

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Parvicapsula minibicornis infections in gill and kidney and the premature mortality of adult sockeye salmon (Oncorhynchus nerka) from Cultus Lake, British Columbia

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f10-017 ◽

2010 ◽

Vol 67 (4) ◽

pp. 673-683 ◽

Cited By ~ 48

Author(s):

Michael J. Bradford ◽

Jan Lovy ◽

David A. Patterson ◽

David J. Speare ◽

William R. Bennett ◽

...

Keyword(s):

British Columbia ◽

Sockeye Salmon ◽

Oncorhynchus Nerka ◽

Premature Mortality ◽

Fraser River ◽

Myxosporean Parasite ◽

Gill Disease ◽

Gill Lamellae ◽

Severity Of The Disease ◽

Using Data

In recent years, large losses of migrating adult sockeye salmon ( Oncorhynchus nerka ) from the Fraser River, British Columbia, Canada, have resulted in reductions in catches and productivity. We investigated patterns of mortality and the occurrence of the myxosporean parasite Parvicapsula minibicornis in adult sockeye salmon from Cultus Lake, tributary to the Fraser River. Using data from a captive broodstock program, we found that early migrants to Cultus Lake had less severe P. minibicornis infections and were more likely to survive to maturity than those fish that arrived later after they had presumably held in the warmer Fraser River. We found P. minibicornis in kidneys and gills of spawners. In some fish, significant histopathology in the gills that included severe inflammation and hyperplasia of the gill lamellae was observed; the severity of the disease was correlated with the severity of P. minibicornis infections. Kidney and gill pathologies were more prevalent and more severe in fish that died before spawning compared with those that matured successfully. Gill disease associated with P. minibicornis infections had not been previously identified in Fraser River sockeye salmon, and its role in the loss of spawners needs further investigation.

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