Patterns of covariation in length and age at maturity of British Columbia and Alaska sockeye salmon (Oncorhynchus nerka) stocks

1999 ◽  
Vol 56 (6) ◽  
pp. 1046-1057 ◽  
Author(s):  
Brian J Pyper ◽  
Randall M Peterman ◽  
Michael F Lapointe ◽  
Carl J Walters
Keyword(s):  
British Columbia ◽  
Survival Rate ◽  
Body Length ◽  
Sockeye Salmon ◽  
Large Scale ◽  
Oncorhynchus Nerka ◽  
Regional Scale ◽  
Survival Rates ◽  
Age At Maturity ◽  
Environmental Processes

We examined patterns of covariation in age-specific adult body length and in mean age at maturity among 31 sockeye salmon (Oncorhynchus nerka) stocks from western Alaska to southern British Columbia. Positive covariation in body length was prevalent across stocks of all regions (e.g., correlations (r) from 0.2 to 0.6), suggesting either that growth periods critical to final body length of sockeye salmon occur while ocean distributions of these stocks overlap or that large-scale environmental processes influence these stocks similarly while they do not overlap. We also found stronger covariation among body length of stocks within regions (r from 0.4 to 0.7), indicating that unique regional-scale processes were also important. Mean age at maturity also showed positive covariation both among and within regions, but correlations were weaker than those for length. We also examined patterns of covariation between length and mean age at maturity and between these variables and survival rate. Although length and mean age at maturity were negatively correlated, there was little evidence of covariation between these variables and survival rate, suggesting that environmental processes that influence marine survival rates of sockeye salmon are largely different from those affecting size and age at maturity.

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

1985 ◽  
Vol 42 (10) ◽  
pp. 1595-1607 ◽  
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.

The distribution of plerocercoids of Diphyllobothrium dendriticum (Nitzsch) in sockeye salmon (Oncorhynchus nerka) smolts from Great Central Lake, British Columbia

1988 ◽  
Vol 66 (4) ◽  
pp. 850-852 ◽  
Author(s):  
Hilda Lei Ching
Keyword(s):  
British Columbia ◽  
Body Length ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Vancouver Island ◽  
Infected Fish ◽  
Mean Intensity ◽  
Diphyllobothrium Dendriticum ◽  
Pyloric Ceca

Sockeye salmon (Oncorhynchus nerka) from Great Central Lake, Vancouver Island, British Columbia, were sampled in May of 1986 and 1987 to study the locations and sizes of plerocercoids of Diphyllobothrium dendriticum. In 1986, 93% of 59 smolts were infected with a total of 222 plerocercoids (mean intensity ± SE, 4.0 ± 3.4; range, 1–15). In 1987, 77% of 168 smolts were infected with a total of 341 plerocercoids (mean ± SE, 2.6 ± 1.8; range, 1–9). More than 75% of the infected fish contained one to three plerocercoids, which were more often found free in the musculature than encysted in the viscera. Plerocercoids occurred most frequently in the midepaxial and midhypaxial musculature and encysted on the stomach and pyloric ceca. Plerocercoids varied in body length: those from the stomach area were <2 mm, and those in the viscera and musculature were 3–10 mm (a few from the musculature were >10 mm).

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

1984 ◽  
Vol 41 (12) ◽  
pp. 1814-1824 ◽  
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.

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

1986 ◽  
Vol 43 (2) ◽  
pp. 269-274 ◽  
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.

Long-term trends in age-specific recruitment of sockeye salmon (Oncorhynchus nerka) in a changing environment

2004 ◽  
Vol 61 (12) ◽  
pp. 2455-2470 ◽  
Author(s):  
Carrie A Holt ◽  
Randall M Peterman
Keyword(s):  
Kalman Filter ◽  
Sockeye Salmon ◽  
Large Scale ◽  
Oncorhynchus Nerka ◽  
Age At Maturity ◽  
Age Class ◽  
Sibling Models ◽  
Long Term Trends ◽  
Forecasting Errors

Sibling – age-class (sibling) models, which relate abundance of one age-class of adult sockeye salmon (Oncorhynchus nerka) to abundance of the previous age-class in the previous year, are commonly used to forecast abundance 1 year ahead. Standard sibling models assume constant parameters over time. However, many sockeye salmon populations have shown temporal changes in age-at-maturity. We therefore developed a new Kalman filter sibling model that allowed for time-varying parameters. We found considerable evidence for long-term trends in parameters of sibling models for 24 sockeye salmon stocks in British Columbia and Alaska; most trends reflected increasing age-at-maturity. In a retrospective analysis, the Kalman filter forecasting models reduced mean-squared forecasting errors compared with standard sibling models in 29%–39% of the stocks depending on the age-class. The Kalman filter models also had mean percent biases closer to zero than the standard models for 54%–94% of the stocks. Parameters of these sibling models are positively correlated among stocks from different regions, suggesting that large-scale factors (e.g., competition among stocks for limited marine prey) may be important drivers of long-term changes in age-at-maturity schedules in sockeye salmon.

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

1998 ◽  
Vol 55 (11) ◽  
pp. 2503-2517 ◽  
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.

The Effect of reduction of Predaceous Fish on survival of young Sockeye Salmon at Cultus Lake

1941 ◽  
Vol 5b (4) ◽  
pp. 315-336 ◽  
Author(s):  
R. E. Foerster ◽  
W. E. Ricker
Keyword(s):  
British Columbia ◽  
Survival Rate ◽  
Sockeye Salmon ◽  
Coho Salmon ◽  
Oncorhynchus Nerka ◽  
First Year ◽  
The Mean ◽  
Control Work ◽  
The Cost ◽  
Gill Netting

By persistent gill-netting in Cultus lake, British Columbia, the predaceous fish which feed on young sockeye (Oncorhynchus nerka) have been considerably, though unevenly, reduced in numbers. The populations of squawfish and char, of lengths greater than 200 millimetres, were reduced in three years to about 1/10 of their original numbers. The abundance of trout and coho salmon have been much less affected by netting, if at all, though a considerable number have been killed. From the first year of control operations the survival rate of young sockeye salmon was considerably increased. In the three years which have been tested, the mean survival rate has been increased three and a third times over average conditions prior to control. In absolute figures, this represents 3,800,000 migrants saved, which are expected to yield 380,000 adult sockeye. Even disregarding the important cumulative future increase, the immediate return from the work is a quantity of sockeye whose value is many times greater than the cost of control work.

Relationship among adult body length, abundance, and ocean temperature for British Columbia and Alaska sockeye salmon (Oncorhynchus nerka), 1967–1997

1999 ◽  
Vol 56 (10) ◽  
pp. 1716-1720 ◽  
Author(s):  
Brian J Pyper ◽  
Randall M Peterman
Keyword(s):  
British Columbia ◽  
Time Series ◽  
Body Length ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Gulf Of Alaska ◽  
Reduced Body ◽  
Adult Body ◽  
Northeastern Pacific ◽  
Length Data

Body length of adult Pacific sockeye salmon (Oncorhynchus nerka) has decreased significantly in recent years. We used 69 time series of age-specific body-length data (1967-1997) for 30 sockeye salmon stocks from southern British Columbia to western Alaska to test hypotheses about the effects of oceanographic conditions and competition on growth rate of sockeye salmon. Using principal components analysis (PCA), we constructed a single time series (PC1) that represented the dominant pattern of variability in length-at-age shared among these stocks. Taking into account time trends and autocorrelation in residuals, we found that increases in total Gulf of Alaska sockeye abundance and increases in sea-surface temperature (SST) across the Gulf of Alaska were significantly associated with reduced adult body length. Abundance and SST together accounted for 71% of the variability in PC1. Although researchers have documented increases in both abundance of sockeye salmon and their food in the northeastern Pacific Ocean over the last few decades, it is possible that increased food was more than offset by increased sockeye abundance, leading to greater competition and reduced body size.

Freshwater and marine migration and survival of endangered Cultus Lake sockeye salmon (Oncorhynchus nerka) smolts using POST, a large-scale acoustic telemetry array

2009 ◽  
Vol 66 (5) ◽  
pp. 736-750 ◽  
Author(s):  
David W. Welch ◽  
Michael C. Melnychuk ◽  
Erin R. Rechisky ◽  
Aswea D. Porter ◽  
Melinda C. Jacobs ◽  
...  
Keyword(s):  
Sockeye Salmon ◽  
Large Scale ◽  
Oncorhynchus Nerka ◽  
Exit Time ◽  
Survival Rates ◽  
Release Site ◽  
Fraser River ◽  
Continental Scale ◽  
Marine Migration ◽  
Post Array

Freshwater and early marine migration and survival of endangered Cultus Lake sockeye ( Oncorhynchus nerka ) salmon were studied using the Pacific Ocean Shelf Tracking (POST) array. Smolts were acoustically tagged in 2004–2007, and their migration was recorded within the lower Fraser River and coastal southern British Columbia waters. Most smolts showed rapid directional movement (swimming speeds of ~15–30 km·day–1). Average exit time from the Fraser River was 4.0–5.6 days after release, and average residence time within the Strait of Georgia was 25.6–34.1 days. Most individuals migrated northward, generally close to the mainland coast. Survival rates, assessed using standard mark–recapture methods, were generally high during the downstream migration (50%–70%), except in 2005 when survival was <20%, possibly because of a late release. Marine survival rates were stable among years, between 10%–30% at a subarray sited 500 km away from the release site. Movement rates were similar to those of previously published work, but the POST array provided direct measurements of movement and estimates of survival and demonstrated the feasibility of establishing continental-scale acoustic arrays for management and conservation of marine species.

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