Dependence of Exploitation Rates for Maximum Yield and Stock Collapse on Age and Sex Structure of Chinook Salmon (Oncorhynchus tshawytscha) Stocks

1986 ◽  
Vol 43 (9) ◽  
pp. 1746-1759 ◽  
Author(s):  
David G. Hankin ◽  
M. C. Healey
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Maximum Yield ◽  
Complex Nature ◽  
Sex Structure ◽  
Early Maturing ◽  
Stock Recruitment ◽  
Mixed Stock ◽  
Age And Sex ◽  
Stock Collapse

In this paper we investigate the equilibrium behavior of an age- and sex-structured version of the Ricker stock–recruitment model specifically tailored to the complex nature of chinook salmon (Oncorhynchus tshawytscha) biology and fisheries. Conclusions from our analysis include the following. (1) Exploitation rates for maximum yield (umsy) and stock collapse (umax) depend strongly on a stock's maturity schedule, being lowest for a late-maturing stock and greatest for an early maturing stock. (2) Values of exploitation rates for umax overlap considerably with those for umsy, emphasizing the probability of stock collapse in fully exploited mixed stock fisheries. (3) Values of umsy and umax are independent of the value of the Ricker β parameter but depend directly on the Ricker α parameter, indicating that management research should focus on obtaining better estimates of α, contrary to recent suggestions in the literature. (4) Because they mature at older ages, female chinook suffer greater cumulative fishery removal rates than males and decline in abundance more rapidly as exploitation increases. Consequently, the use of sex-independent maturity schedules can give misleading estimates for umsy and umax. (5) Maximum changes in mean age of stocks that can be attributed to fishing up effects ranged from 0.32 to 0.81 yr. Many stocks appear already to have declined in mean age by this amount, further emphasizing the probability of impending collapse of some stocks.

Fry-to-adult survival of natural and hatchery-produced chinook salmon (Oncorhynchus tshawytscha) from a common origin

1997 ◽  
Vol 54 (6) ◽  
pp. 1246-1254 ◽  
Author(s):  
M J Unwin
Keyword(s):  
New Zealand ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Survival Rates ◽  
Adult Survival ◽  
Poor Survival ◽  
Stock Size ◽  
Hatchery Fish ◽  
Stock Recruitment

Fry-to-adult survival rates for chinook salmon (Oncorhynchus tshawytscha) from Glenariffe Stream, a tributary of the Rakaia River, New Zealand, were estimated for fish of both natural and hatchery origin. Survival of naturally produced fry, most of which leave Glenariffe Stream within 24 h of emergence, averaged 0.079% (range 0.013-1.17%). For hatchery fish released at 8-12 months, standardised to a mean weight of 38 g, survival covaried with weight at release consistently across all brood years and averaged 0.34% (range 0.008-3.28%). Survival rates for hatchery fish were four times higher than for naturally produced fry, but were extremely poor relative to their size at release. Survival rates for fish of natural and hatchery origin were positively correlated, suggesting that recruitment of both stocks is primarily controlled by common influences within the marine environment, probably during the first winter at sea. Stock-recruitment analysis for the natural population showed little tendency for recruitment to increase with stock size, suggesting that marine survival rates may be density dependent. Although the reasons for the relatively poor survival of hatchery fish are unclear, the results provide a case study in which hatchery fish appear to have a poorer ``fitness to survive'' than their natural counterparts.

scholarly journals Identifying the contribution of wild and hatchery Chinook salmon (Oncorhynchus tshawytscha) to the ocean fishery using otolith microstructure as natural tags

2007 ◽  
Vol 64 (12) ◽  
pp. 1683-1692 ◽  
Author(s):  
Rachel Barnett-Johnson ◽  
Churchill B Grimes ◽  
Chantell F Royer ◽  
Christopher J Donohoe
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Wild Fish ◽  
Otolith Microstructure ◽  
Exogenous Feeding ◽  
Daily Growth ◽  
Wild Salmon ◽  
Growth Increments ◽  
In The Wild ◽  
Mixed Stock

Quantifying the contribution of wild (naturally spawned) and hatchery Chinook salmon (Oncorhynchus tshawytscha) to the mixed-stock ocean fishery is critical to understanding their relative importance to the persistence of salmon stocks. The inability to distinguish hatchery and wild salmon has inhibited the detection of declines or recoveries for many wild populations. By using Chinook salmon of known hatchery and wild origin, we established a baseline for separating these two sources using otolith microstructure. Otoliths of wild salmon contained a distinct exogenous feeding check likely reflecting an abrupt transition in food resources from maternal yolk not experienced by fish reared in hatcheries. Daily growth increments in otoliths from hatchery salmon immediately after the onset of exogenous feeding were wider and more uniform in width than those in wild fish. The discriminant function that we used to distinguish individuals reared in hatcheries or in the wild was robust between years (1999 and 2002), life history stages (juveniles and adults), and geographic regions (California, British Columbia, and Alaska) and classified fish with ~91% accuracy. Results from our mixed-stock model estimated that the contribution of wild fish was 10% ± 6%, indicating hatchery supplementation may be playing a larger role in supporting the central California coastal fishery than previously assumed.

Comment on “Gene flow increases temporal stability of Chinook salmon (Oncorhynchus tshawytscha) populations in the Upper Fraser River, British Columbia, Canada”Appears in Can. J. Fish. Aquat. Sci. 66: 167–176.

2010 ◽  
Vol 67 (1) ◽  
pp. 202-205 ◽  
Author(s):  
Terry D. Beacham ◽  
Ruth E. Withler
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Pacific Salmon ◽  
Temporal Stability ◽  
Time Span ◽  
Population Variation ◽  
Stock Identification ◽  
Fraser River ◽  
Mixed Stock ◽  
Conservation And Management

Temporally stable genetic structure among salmonid populations has been reported in many studies, although the time span evaluated in most studies is limited to 10 years or less. This result has important implications in conservation and management of Pacific salmon ( Oncorhynchus spp.) and ramifications for the construction and application of genetic databases for stock identification of fish sampled from mixed-stock fisheries. Walter et al. (2009. Can. J. Fish. Aquat. Sci. 66: 167–176) failed to consider recent studies providing evidence that their conclusion “the overall magnitude of temporal within-population variation exceeding that of among-population variation” for the populations under study may be invalid for Fraser River Chinook salmon ( Oncorhynchus tshawytscha ) populations. Their estimation of rates and patterns of migration among Chinook salmon populations also provided results that are difficult to reconcile with published information. Evaluation of the experimental designed employed by Walter et al. (2009) indicates that their sample sizes were too small to estimate reliably genetic variation among or within populations. Extrapolation of their conclusions relating temporal instability of population structure to other Chinook salmon populations or indeed other salmonid species is unwarranted.

Comparison of Methods for Estimating Mixed Stock Fishery Composition

1990 ◽  
Vol 47 (11) ◽  
pp. 2235-2241 ◽  
Author(s):  
R. B. Millar
Keyword(s):  
Maximum Likelihood ◽  
Maximum Likelihood Estimator ◽  
Random Sample ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Comparison Of Methods ◽  
Likelihood Estimator ◽  
Mixed Stock ◽  
Theoretical Considerations ◽  
Scale Data

Given information on fish of known origin, and a random sample from the mixed stock fishery, the composition of that mixed fishery may be estimated in a number of ways. This study compares the performance of four classification-based estimators and a maximum likelihood estimator. Theoretical considerations show that the maximum likelihood estimator makes better use of the information contained in the mixed fishery sample. However, the classification estimators are shown to be more robust to violations in some of the model assumptions. Scale data from four regional stock groups of chinook salmon (Oncorhynchus tshawytscha) were used in an applied comparison of the five estimators. The results suggest that the maximum likelihood estimator performs best in practice.

Low productivity of Chinook salmon strongly correlates with high summer stream discharge in two Alaskan rivers in the Yukon drainage

2015 ◽  
Vol 72 (8) ◽  
pp. 1125-1137 ◽  
Author(s):  
Jason R. Neuswanger ◽  
Mark S. Wipfli ◽  
Matthew J. Evenson ◽  
Nicholas F. Hughes ◽  
Amanda E. Rosenberger
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Population Declines ◽  
Environmental Predictors ◽  
High Discharge ◽  
Stream Discharge ◽  
Yukon River ◽  
Stock Recruitment ◽  
Sources Of Variation ◽  
Major Floods

Yukon River Chinook salmon (Oncorhynchus tshawytscha) populations are declining for unknown reasons, creating hardship for thousands of stakeholders in subsistence and commercial fisheries. An informed response to this crisis requires understanding the major sources of variation in Chinook salmon productivity. However, simple stock–recruitment models leave much of the variation in this system’s productivity unexplained. We tested adding environmental predictors to stock–recruitment models for two Yukon drainage spawning streams in interior Alaska — the Chena and Salcha rivers. Low productivity was strongly associated with high stream discharge during the summer of freshwater residency for young-of-the-year Chinook salmon. This association was more consistent with the hypothesis that sustained high discharge negatively affects foraging conditions than with acute mortality during floods. Productivity may have also been reduced in years when incubating eggs experienced major floods or cold summers and falls. These freshwater effects — especially density dependence and high discharge — helped explain population declines in both rivers. They are plausible as contributors to the decline of Chinook salmon throughout the Yukon River drainage.

Evidence for Inheritance of Age of Maturity in Chinook Salmon (Oncorhynchus tshawytscha)

1993 ◽  
Vol 50 (2) ◽  
pp. 347-358 ◽  
Author(s):  
David G. Hankin ◽  
Jay W. Nicholas ◽  
Timothy W. Downey
Keyword(s):  
Growth Rate ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Negative Bias ◽  
Parental Age ◽  
Minimum Threshold ◽  
Older Parents ◽  
Age Of Maturity ◽  
Males And Females ◽  
Age And Sex

We report results of age-specific mating experiments carried out with chinook salmon (Oncorhynchus tshawytscha) at Elk River Hatchery, Oregon. Our analysis of returns from these experiments includes assessment of the marine growth of progeny, and we also account for the negative bias on mean age of returning mature progeny that is a consequence of troll fishery harvest of immature salmon. Results suggest that (a) heritability of age of maturity is relatively high in this species (calculated h2 were 0.49–0.57 and 0.39–0.41 for males and females, respectively), (b) inheritance of age of maturity of females appears to be independent of age of male parent, and (c) for a given parental age, "faster-growing" progeny generally mature at younger ages, but (d) progeny from older parents are not generally smaller at age than progeny from younger parents. Inheritance of age of maturity therefore cannot be a simple reflection of inheritance of growth rate. We tentatively propose the existence of heritable minimum threshold lengths that differentially trigger maturation according to age and sex of parents. We also consider the significance of these experiments for artificial propagation of this species.

Multivariate Morphometric Variability in Pacific Salmon: Technical Demonstration

1984 ◽  
Vol 41 (8) ◽  
pp. 1150-1159 ◽  
Author(s):  
Gary A. Winans
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Pacific Salmon ◽  
Specific Information ◽  
Data Sets ◽  
Morphometric Data ◽  
Morphometric Characters ◽  
Hatchery Stock ◽  
Mixed Stock ◽  
And Storage

A computer oriented approach to the collection and analysis of morphometric characteristics in juvenile chinook salmon (Oncorhynchus tshawytscha) is described. A three-step data collection and storage method is used whereby X–Y coordinate data for relevant morphological features on a body form are collected with a digitizing pad and used to calculate morphometric characters. To test this method, I calculated two morphometric data sets, a conventional and a truss network, and compared them by multivariate analysis in a preliminary study of growth and development in one hatchery stock of fish, and in a survey of population differences in three naturally occurring populations of chinook salmon. Technical advantages of using a digitizing pad for collecting morphometric data are demonstrated. Hatchery-reared chinook salmon showed marked changes in body shape during the period of spring smoltification when marked changes in condition factor occurred. Multivariate differences were discerned among the three Oregon coastal stocks. Truss data provided more specific information concerning shape changes in the study of early development and produced greater between-group differences in the geographic survey. The results of these preliminary analyses can be applied to problems of identifying smolt status in hatchery fish and stock origin in mixed-stock fisheries.

Wild Chinook salmon productivity is negatively related to seal density and not related to hatchery releases in the Pacific Northwest

2019 ◽  
Vol 76 (3) ◽  
pp. 447-462 ◽  
Author(s):  
Benjamin W. Nelson ◽  
Carl J. Walters ◽  
Andrew W. Trites ◽  
Murdoch K. McAllister
Keyword(s):  
Pacific Northwest ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Maximum Sustainable Yield ◽  
Bayesian Hierarchical ◽  
The Pacific ◽  
Bioenergetics Modeling ◽  
Stock Recruitment ◽  
High Conservation ◽  
Conservation Concern

Predation risk and competition among conspecifics significantly affect survival of juvenile salmon, but are rarely incorporated into models that predict recruitment in salmon populations. Using densities of harbour seals (Phoca vitulina) and numbers of hatchery-released Chinook salmon (Oncorhynchus tshawytscha) smolts as covariates in spatially structured Bayesian hierarchical stock–recruitment models, we found significant negative correlations between seal densities and productivity of Chinook salmon for 14 of 20 wild Chinook populations in the Pacific Northwest. Changes in numbers of seals since the 1970s were associated with a 74% decrease (95% CI: −85%, −64%) in maximum sustainable yield in Chinook stocks. In contrast, hatchery releases were significantly correlated with Chinook productivity in only one of 20 populations. Our findings are consistent with recent research on predator diets and bioenergetics modeling that suggest there is a relationship between harbour seal predation on juvenile Chinook and reduced marine survival in parts of the eastern Pacific. Forecasting, assessment, and recovery efforts for salmon populations of high conservation concern should thus consider including biotic factors, particularly predator–prey interactions.

Integration of natural and artificial markers in a mixed stock analysis of Chinook salmon (Oncorhynchus tshawytscha)

2010 ◽  
Vol 102 (1-2) ◽  
pp. 152-159 ◽  
Author(s):  
Jessica A. Miller ◽  
M. Renee Bellinger ◽  
James T. Golden ◽  
Lorissa Fujishin ◽  
Michael A. Banks
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Mixed Stock Analysis ◽  
Stock Analysis ◽  
Mixed Stock

Critical Size and Maximum Yield for Chinook Salmon (Oncorhynchus tshawytscha)

1960 ◽  
Vol 17 (2) ◽  
pp. 199-210 ◽  
Author(s):  
Robert R. Parker
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Critical Size ◽  
Maximum Yield ◽  
Minimum Size ◽  
Relative Growth Rates ◽  
Size Regulation ◽  
Direct Injury ◽  
Feasible Alternative ◽  
Temporal Restriction

Instantaneous natural mortality rate is estimated from tagging and recovery data and compared with instantaneous relative growth rates for each life history type of chinook salmon. It is demonstrated that critical size is not attained prior to maturity, hence, juveniles should be protected from fishing if maximum yield in pounds is desired. Yield cannot be increased by a minimum size regulation, for losses due both to direct injury and hyperactivity reduce critical size to levels not ordinarily encountered by existing fisheries. A further complication arises in that size is not a reliable indicator of maturity. The most feasible alternative to a minimum size regulation appears to be spatial and temporal restriction of the fishery to known concentrations of maturing fish, together with the encouragement of non-size-selective gear.

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