Updated squid assessment results
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2013
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University of Cape Town
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Abstract
Glazer & Butterworth (2013) reports progress on refinements to the squid stock assessment model focusing particularly on replacing the discrete Pope catch equations with differentiable Baranov catch equations as recommended by the Panel of the International Stock Assessment Workshop held at UCT in December 2012. A comparison of key parameter estimates as per the Pope and Baranov models (utilizing data to 2011) indicated that although initial recruitment, and hence biomass, is estimated to be somewhat higher for the Baranov model (driven mainly by the lower estimate of h in that model), the ratio of current stock status relative to pristine (��2012 ∗ ��1971 ∗ ) was at a similar level for both models. This paper reports further results to those in Glazer & Butterworth (2013): • A comparison of risk statistics for the Pope and Baranov models where each model was projected 5000 times into the future from their joint posterior mode values • Updated joint posterior mode parameter estimates for the Baranov model including data to 2012
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Reference:
Glazer, J. P., & Butterworth, D. S. (2013). Updated squid assessment results. FISHERIES/2013/AUG/SWG-SQ/49