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Implementing the 2014 three-stock model for Southern Hemisphere Breeding Stocks E1, Oceania and G

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posted on 2022-03-25, 12:36 authored by Andrea Ross-GillespieAndrea Ross-Gillespie, Doug ButterworthDoug Butterworth
The three stock model approach with mixing on feeding grounds, which was implemented in 2014 to assess the BSD, BSE1 and BSO breeding stocks, is applied in a similar manner to the BSE1, BSO and BSG breeding stocks. This is intended as a first step in applying this approach consecutively around the globe to check for consistency of results in circumstances of uncertainty in the allocation of feeding ground catches. Compared to earlier assessments of the BSE1, BSO and BSG breeding stocks in partly separate analyses, there is an appreciable change in that the pre-exploitation level is estimated higher for BSE1and lower for BSO; correspondingly, BSE1 is estimated as less and BSO as more recovered towards those pre-exploitation levels. Comparable likelihoods do not differ greatly for data for these stocks used in both the 2014 BSD+BSE1+BSO and the 2015 BSE1+BSO+BSG assessments, suggesting that the data used here do not contain sufficient information to distinguish these rather different results.

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Department of Mathematics and Applied Mathematics, University of Cape Town