Sustainable Fisheries Stock Assessment Update & Biological Reference Points
This document provides insights into the 2017 stock assessment update for sustainable fisheries, focusing on blue crab population analysis, abundance estimates, exploitation rates, and biological reference points comparison between 2011 and 2017. Findings suggest model stability and non-depletion of stock status.
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Presentation Transcript
Stock Assessment Update & Biological Reference Points Sustainable Fisheries GIT Meeting 1/12/2021
2017 Stock Assessment Update Updates the 2011 blue crab stock assessment Same model: Sex specific catch multiple survey analysis Same parameters Growth, fecundity, stock-recruitment Natural mortality (M=0.9) Proportion of juveniles recruited to the fishery within the year (rf=0.6) Proportion of females recruited to the population (prop fem = 0.52)
2017 Stock Assessment Update Data inputs Abundance updated through 2017, landings updated through 2016. Indices of abundance VIMS trawl (geometric mean, 1968-2017) MDNR trawl (delta-lognormal mean, 1977-2017) WDS (stratified arithmetic mean, 1990-2017) Landings Includes intervention functions 1968-1993. MDNR (estimated) VMRC PRFC
2017 Stock Assessment Update Findings Very little change from the 2011 assessment Updated estimates of abundance had a high correlation with 2011 estimates and empirical estimates. Updated exploitation rates highly correlated with 2011 estimates, better with empirical estimates 2010-2016. Biological reference points from 2011 stock assessment and the 2017 update 2011 Threshold Target Threshold 215 mil 70 mil 25.5% 34% 2017 Target Abundance Exploitation 196 mil 28% 72.5 mil 37%
2017 Stock Assessment Update Female exploitation rate with biological reference points. Presented are updated estimates of exploitation and reference points, estimates and reference points from the 2011 stock assessment, and empirical estimates.
2017 Stock Assessment Update Adult female abundance with biological reference points. Presented are updated estimates of abundance and reference points, estimates and reference points from the 2011 stock assessment, and empirical estimates.
2017 Stock Assessment Update Conclusions Stock status remained unchanged not depleted/over- fished and over-fishing was not occurring. Similar results to 2011 assessment (BRPs, estimates of abundance/catch) likely indicate model stability.
Biological Reference Points CBSAC meeting Oct 20, 2020 hosted SFGIT ex-comm to discuss and vote on new reference points Updated biological reference points from the 2017 stock assessment update were approved Consensus was the new reference points are the best available science and should be adopted for management
