Adjustment of a Bayesian surplus production model for Northern shrimp for stocks in the Gulf of St. Lawrence

Abstract

As part of the review of the precautionary approach for northern shrimp in the Estuary and northern Gulf of St. Lawrence (ENGSL), a Bayesian, state-space, surplus production model was fit to commercial landings and the biomass index for each of the four stocks. This document describes the methods used to fit the Bayesian surplus production model to biomass data for the northern shrimp stocks in the ENGSL. According to the results obtained, this model could be useful for assessing stock status and for revising the precautionary approach. The results presented here are consistent with the findings of the previous assessment and show that the Esquiman, Anticosti and Sept-Iles stocks have been declining for several years, with biomass values in 2022 falling to the lowest levels observed since 1990. The results also show that the Estuary stock is currently stable with high biomass values.