North Pacific Anadromous Fish Commission

Technical Report 15

Table of Contents

Evaluating Impacts of Time-varying Productivity in Stock-recruit Relationships on Biological Benchmarks

Authors:
Carrie A. Holt and Catherine G.J. Michielsens

Abstract Excerpt:
Time-varying models that account for changes in productivity are increasingly being applied to assess fish stocks, including Pacific salmon (Peterman et al. 2000; Dorner et al. 2008; Peterman and Dorner, 2012), but their reliability under different harvest and productivity scenarios has not been thoroughly evaluated. In particular, the Kalman filter has been used as an analytical tool to identify time-varying productivity in Pacific salmon stocks assessed with a Ricker stock-recruit relationship (Peterman et al. 2000). While variability in the underlying spawner and recruitment data, e.g., due to variability in a stock’s exploitation history, may impact the relative performance of models, this has not been considered in model evaluations. In addition, the implications of time-varying productivity on the derivation of biological reference points or benchmarks have not been quantified for Pacific salmon. Here, we evaluated stock-recruitment models with and without time-varying productivity parameters in a closed-loop simulation model of sockeye salmon (Oncorhynchus nerka). This modelling approach allowed us to evaluate biases and precision of parameter estimates under various hypotheses about trajectories in productivity and exploitation rates, and their implications on biological benchmarks.

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DOI:
https://doi.org/10.23849/npafctr15/145.147.

Citation

Holt, C.A., and C.G.J. Michielsens.  2019.  Evaluating impacts of time-varying productivity in stock-recruit relationships on biological benchmarks.  N. Pac. Anadr. Fish Comm. Tech. Rep. 15: 145–147.  https://doi.org/10.23849/npafctr15/145.147.