FISHERIES_2015_OCT_SWG-DEM_40.pdf (573.46 kB)
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Updated assessment of the toothfish (Dissostichus eleginoides) resource in the Prince Edward Islands vicinity to include data from 1997 to 2015, including tag-recapture data

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The assessment of the Prince Edward Islands (PEI) toothfish (Dissostichus eleginoides) resource carried out by Brandão and Butterworth (2014) is updated to take further data available for 2014 and 2015 (up to June) into account. This update again also incorporates tag-recapture data and a new basis to estimate the extent of cetacean depredation. For the Base Case and many of the assessment sensitivities the resource is estimated to be at a depletion (in relation to its average pre-exploitation level in terms of spawning biomass) in the 53-60% range. Introduction of the tag-recapture data hardly changes point estimates but does reduce estimation variance. Projections suggest that the resource would increase slowly under constant annual future catches of 500 t. This would remain the case for somewhat higher catches as well, but it remains a concern that for the last three years the longline CPUE is well below model predictions and there is a drop in the trotline CPUE index for 2014, which is the lowest in the series. In these circumstances, a possible recommendation to increase the TAC beyond 575 t should perhaps first await further trotline CPUE data.

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Department of Mathematics and Applied Mathematics, University of Cape Town