Dr. André E. Punt1 and Dr. Jason Cope2
1School of Aquatic and Fishery Science
2Northwest Fisheries Science Center
November 18, 2014

Simple Stock Synthesis (SSS) and Depletion-Based Stock Reduction Analysis (DB-SRA) are two methods for calculating overfishing limits for data-poor fish stocks. Both methods are Bayesian in that priors are imposed on the parameters of the underlying population dynamics model (although there is no information to update the priors). DSB-SRA is based on a generalized production function which allows independent priors to be imposed on BMSY/B0 and FMSY/B0. However, SSS is based on the Beverton-Holt stock-recruitment relationship so there is a functional relationship between BMSY/B0 and FMSY/B0 as expressed in the steepness parameter (h). We outline two stock-recruitment relationships (the Shepherd and Generalized Ricker) which if incorporated in Stock Synthesis may allow the goal of independent priors to be imposed on BMSY/B0 and FMSY/B0 to be achieved. We show for some example species how well these stock-recruitment relationships achieve this goal and compare DB-SRA and SSS when they are applied to some example rockfish stocks.

Posted in Fisheries Think Tank.

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