scholarly journals Stock-recruitment models, principles of management and rules for regulating the fishery on the main Chukotka stocks of sockeye and chum salmon

2021 ◽  
Vol 201 (3) ◽  
pp. 735-751
Author(s):  
E. A. Shevlyakov ◽  
M. G. Feldman ◽  
A. N. Kanzeparova
Keyword(s):  
Sockeye Salmon ◽  
Chum Salmon ◽  
Fishery Management ◽  
Pacific Salmon ◽  
Far East ◽  
Simulation Models ◽  
Processing Capacity ◽  
Spawning Stock ◽  
Stock Recruitment ◽  
Recruitment Model

Fishery pressure on populations of pacific salmons has increased in the Rusian Far East in the last decade because of growing fishing and processing capacity, so measures for the fishery regulation are necessary, as the regime of pass days in rivers and marine coastal areas. Chukotka is now almost the only region where such restrictions are still absent. However, if the interest of fishery industry to the stocks of pacific salmon in Chukotka will grow, a successful scientifically based strategy of fishery should be developed to maintain exploitation of the stocks without exceeding the limits of excessive use. Year-to-year time series on spawning stock and recruitment of chum salmon in the Anadyr area and sockeye salmon in the Meynypilgyn area were analysed for development of recruitment models and establishment of general principles for adaptive fishery management. Nonlinear adaptive fishery management based on principles of buffer managing is proposed and tested under various regimes of landing using the stock simulation models accounting deviations from the standard stock-recruitment model. There is concluded that the level of exploitation is much lower than optimal for the Anadyr chum salmon, whereas escapement for spawning of the Meynypilgyn sockeye salmon should be increased in cases of low spawning stock of this species.

scholarly journals An explicit solution for calculating optimum spawning stock size from Ricker’s stock recruitment model

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1623 ◽  
Author(s):  
Mark D. Scheuerell
Keyword(s):  
Explicit Solution ◽  
Model Fitting ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Stock Size ◽  
Points Of Interest ◽  
Spawning Stock ◽  
Stock Recruitment ◽  
Explicit Formulae ◽  
Recruitment Model

Stock-recruitment models have been used for decades in fisheries management as a means of formalizing the expected number of offspring that recruit to a fishery based on the number of parents. In particular, Ricker’s stock recruitment model is widely used due to its flexibility and ease with which the parameters can be estimated. After model fitting, the spawning stock size that produces the maximum sustainable yield (SMSY) to a fishery, and the harvest corresponding to it (UMSY), are two of the most common biological reference points of interest to fisheries managers. However, to date there has been no explicit solution for either reference point because of the transcendental nature of the equation needed to solve for them. Therefore, numerical or statistical approximations have been used for more than 30 years. Here I provide explicit formulae for calculating bothSMSYandUMSYin terms of the productivity and density-dependent parameters of Ricker’s model.

scholarly journals Adaptive Control of Fishing Systems

1976 ◽  
Vol 33 (1) ◽  
pp. 145-159 ◽  
Author(s):  
Carl J. Walters ◽  
Ray Hilborn
Keyword(s):  
Sockeye Salmon ◽  
Optimization Methods ◽  
Fishing Effort ◽  
Model Parameters ◽  
Fraser River ◽  
The Face ◽  
Stock Recruitment ◽  
Best Fitting ◽  
Uncertainty Parameter ◽  
Recruitment Model

This paper discusses some formal techniques for deciding how harvesting policies should be modified in the face of uncertainty. Parameter estimation and dynamic optimization methods are combined for the Ricker stock-recruitment model to show how exploitation rates should be manipulated to give more information about the model parameters; in general, harvesting rates should be lower than would be predicted by the best fitting recruitment curve unless this curve predicts that the stock is very productive. A decision procedure is developed for comparing alternative stock-recruitment models; when applied to the Fraser River sockeye salmon (Oncorhynchus nerka), the procedure indicates that an experimental increase in escapements would be quite worthwhile. It appears that there is considerable promise for extending these methods and procedures to cases where the stock size is unknown and where fishing effort is poorly controlled.

scholarly journals Delay in fishery management: diminished yield, longer rebuilding, and increased probability of stock collapse1

2006 ◽  
Vol 64 (1) ◽  
pp. 149-159 ◽  
Author(s):  
Kyle W. Shertzer ◽  
Michael H. Prager
Keyword(s):  
Fishery Management ◽  
Economic Loss ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Short Term ◽  
Stock Status ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Stock Recruitment ◽  
Stock Collapse

Abstract Shertzer, K. W., and Prager, M. H. 2007. Delay in fishery management: diminished yield, longer rebuilding, and increased probability of stock collapse. ICES Journal of Marine Science, 64: 149–159. When a stock is depleted, catch reductions are in order, but typically they are implemented only after considerable delay. Delay occurs because fishery management is political, and stricter management, which involves short-term economic loss, is unpopular. Informed of stock decline, managers often hesitate, perhaps pondering the uncertainty of scientific advice, perhaps hoping that a good year class will render action moot. However, management delay itself can have significant costs, when it exacerbates stock decline. To examine the biological consequences of delay, we simulated a spectrum of fisheries under various degrees of delay in management. Increased delay required larger catch reductions, for more years, to recover benchmark stock status (here, spawning-stock biomass at maximum sustainable yield). Management delay caused stock collapse most often under two conditions: (1) when the stock–recruitment relationship was depensatory, or (2) when catchability, unknown to the assessment, was density-dependent and fishing took juveniles. In contrast, prompt management resulted in quicker recoveries and higher cumulative yields from simulated fisheries. Benefits to stock biomass and fishery yield can be high from implementing management promptly.

Escapement goal analysis and stock reconstruction of sockeye salmon populations (Oncorhynchus nerka) using life-history models

2008 ◽  
Vol 65 (10) ◽  
pp. 2269-2278 ◽  
Author(s):  
Robert B. Lessard ◽  
Ray Hilborn ◽  
Brandon E. Chasco
Keyword(s):  
Life History ◽  
Sockeye Salmon ◽  
Model Estimate ◽  
Policy Variable ◽  
Optimal Harvest ◽  
Spawning Stock ◽  
Maximum Sustained Yield ◽  
History Of ◽  
Stock Recruitment

We compare life-history models with the Beverton–Holt approach of escapement goal analysis. We model the life history of a sockeye salmon ( Onchorhynchus nerka ) population from a spawning stage, through juvenile and adult stages, and ending with adults that return to spawn. We fit models to data by statistically comparing predicted and observed numbers of four dominant adult ages. Posterior estimates of parameters from Markov chain Monte Carlo simulations are then used to assess optimal harvest policies. We search for policies that produce the highest average yield. We find that it is possible to detect density dependence with a life-history model where analysis of Beverton–Holt stock–recruitment relationship fails to do so. We find that Beverton–Holt relationships produce policies and long-term yield estimates that are inconsistent with empirical trends. Conversely, we find that optimal spawning stock sizes and maximum sustained yield estimates using the life-history model estimate are consistent with the historical behavior of fisheries examined. Adding smolt data to the analysis does not substantially change predicted optimal spawning stock size, but decreases the variance in estimated posterior parameter distributions and policy variable distributions.

Uncertainties in population dynamics and outcomes of regulations in sockeye salmon (Oncorhynchus nerka) fisheries: implications for management

2008 ◽  
Vol 65 (7) ◽  
pp. 1459-1474 ◽  
Author(s):  
Carrie A. Holt ◽  
Randall M. Peterman
Keyword(s):  
Sockeye Salmon ◽  
Management Practices ◽  
Pacific Salmon ◽  
Oncorhynchus Nerka ◽  
Simulation Models ◽  
Age At Maturity ◽  
Sources Of Uncertainty ◽  
Future Assessment ◽  
Long Term Trends

Fisheries managers usually have multiple options available but are often unclear on how to choose among them owing to uncertainties in biological and management components of fisheries systems. We evaluated the performance of current and possible future assessment and management practices for sockeye salmon ( Oncorhynchus nerka ) in British Columbia and Alaska by using a computer model that included major biological and management components and their associated uncertainties (interannual variability in recruitment, age-at-maturity, and sex ratio, as well as uncertainty in observations of spawner abundances, forecasts of recruitment, and outcomes from implementing management regulations). One option for management practices that we evaluated was designed to make the forecasting model more realistic by accounting for long-term trends in age-at-maturity. A second option was designed to reduce deviations between management targets and actual or “realized” harvest levels. We found that compared with practices that ignore those sources of uncertainty, the second option produced annual catches that were higher, on average, and less variable over time while maintaining recruitment above critical conservation levels. Contrary to our expectations, the first modification did not result in comparable benefits. Our results demonstrate the value of using simulation models to evaluate potential modifications to Pacific salmon management practices.

scholarly journals An explicit solution for calculating optimum spawning stock size from Ricker's stock recruitment curve

2015 ◽  
Author(s):  
Mark D. Scheuerell
Keyword(s):  
Explicit Solution ◽  
Model Fitting ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Stock Size ◽  
Points Of Interest ◽  
Spawning Stock ◽  
Stock Recruitment ◽  
Explicit Formulae ◽  
Recruitment Model

Ricker’s stock recruitment model is widely used to describe the spawner-offspring relationship for fishes. After model fitting, the spawning stock size that produces the maximum sustainable yield (SMSY), and the harvest corresponding to it (UMSY), are two of the most common biological reference points of interest to fisheries managers. However, to date there has been no explicit solution for either reference point because of the transcendental nature of the equation needed to solve for them. Therefore, numerical or statistical approximations have been used for more than 30 years. Here I provide explicit formulae for calculating both SMSY and UMSY in terms of the productivity and density-dependent parameters from Ricker’s model.

The estimation and robustness of FMSY and alternative fishing mortality reference points associated with high long-term yield

2012 ◽  
Vol 69 (9) ◽  
pp. 1468-1480 ◽  
Author(s):  
Jan Horbowy ◽  
Anna Luzeńczyk
Keyword(s):  
Total Yield ◽  
Reference Points ◽  
Superior Performance ◽  
Equilibrium Yield ◽  
Spawning Stock ◽  
Stock Recruitment ◽  
Yield Per Recruit ◽  
Different Sources ◽  
Recruitment Model

Equations for equilibrium yield and biomass are presented and used to derive FMSY and alternative reference points (ARPs). ARPs are analogues of the traditional points based on yield-per-recruit (YPR) or spawning stock-per-recruit (SPR) (F0.1, F40%, F50%), but refer to the equilibrium total yield or biomass. The method combines YPR and SPR analysis with stock–recruitment relationships. The sensitivity of FMSY and ARPs to the range of available stock–recruitment data, recruitment variance, various steepness levels in the stock–recruitment models, assessment variance, and bias are tested. The analysis showed that in most cases, F40%B and F50%B, defined by the equilibrium biomass (B), were the most robust relative to the different sources of uncertainty. However, in the case of the misspecification of the stock–recruitment relationship, FMSY showed superior performance. F40%B for the Beverton and Holt stock–recruitment model and F50%B for the Ricker recruitment model can be recommended as conservative fishing mortalities associated with high long-term yield. For the considered steepness, they produced yield up to 5%–10% lower than yield at FMSY.

Application of microsatellite DNA variation to estimation of stock composition and escapement of Nass River sockeye salmon (Oncorhynchus nerka)

1999 ◽  
Vol 56 (2) ◽  
pp. 297-310 ◽  
Author(s):  
Terry D Beacham ◽  
Chris C Wood
Keyword(s):  
Microsatellite Dna ◽  
Sockeye Salmon ◽  
Fishery Management ◽  
Pacific Salmon ◽  
Oncorhynchus Nerka ◽  
River Mouth ◽  
Large River ◽  
Allele Frequencies ◽  
Dna Variation ◽  
Mixed Stock

Spawning escapements of individual Pacific salmon stocks returning to remote spawning locations throughout large river systems can in theory be estimated by mixed-stock analysis of appropriately weighted samples from test fisheries near the river mouth. However, the feasibility of this approach has usually been limited by practical difficulties in identifying closely related populations within the same watershed. Microsatellite DNA techniques offer new promise for overcoming these limitations as illustrated for sockeye salmon (Oncorhynchus nerka) in the Nass River of northern British Columbia. Variation at six microsatellite DNA loci (Omy77, Ots3, Ots100, Ots103, Ots107, and Ots108) was surveyed from about 1400 fish from nine stocks in the Nass River drainage as well as from 249 fish in a test fishery conducted in the lower river during 1996. Five stocks were surveyed in more than one year, and variation in allele frequencies among stocks was, on average, about 10 times greater than annual variation within stocks. Allele frequencies of stocks where the juveniles do not rear in lakes ("riverine" or "sea type") were more similar to each other compared with frequencies from lake-rearing stocks. Significant differences in allele frequencies were observed among most stocks at all loci. About 4.5% of observed variation over all loci was attributable to stock differentiation. Simulated mixed-stock samples suggested that the six microsatellite DNA loci surveyed should provide the ability to provide relatively accurate and precise estimates of stock composition when utilized for fishery management applications. The estimated proportion of Meziadin Lake sockeye salmon in the 1996 test fishery was about 73%, in close agreement with an estimate derived from direct tagging of fish in the test fishery.

Ocean Migrations of Pacific Salmon

1964 ◽  
Vol 21 (5) ◽  
pp. 1227-1244 ◽  
Author(s):  
Ferris Neave
Keyword(s):  
Coastal Area ◽  
Sockeye Salmon ◽  
Chum Salmon ◽  
Pacific Salmon ◽  
Oncorhynchus Nerka ◽  
Pink Salmon ◽  
Direct Approach ◽  
Spawning Area ◽  
Inshore Waters ◽  
High Seas

Sockeye salmon (Oncorhynchus nerka), pink salmon (O. gorbuscha), and chum salmon (O. keta) commonly return to their places of origin from distant high-seas areas. Maturing fish closely associated at high-seas localities travel in many different directions to their respective destinations. They also travel from many different high-seas localities to a common coastal area. Prior to their return to inshore waters, pink salmon perform ocean journeys which are associated with changes in temperature and which do not necessarily represent a direct approach to a spawning area. The ocean journeys of both juvenile and maturing salmon are largely independent of currents. Homing is not thought to be commonly accomplished by random or near-random ocean travel or by extensive searching of coastlines. It is suggested that ability to set a compass course, using a celestial feature, is insufficient to account for the indicated performance and that some form of bico-ordinate navigation may be required.

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