Research plan for the exploratory longline fishery for Dissostichus spp. in 2014/15 in Division 58.4.3a

In 2011/2012, the Saint André conducted its first exploratory fishery for Dissostichus spp. in division 58.4.3a. France notified its wish to continue this exploratory fishery over the coming years in order to achieve a robust stock assessment that would provide advice on a catch limit according to CCAMLR decision rules. This paper aims to present a research plan for 2014/2015 that takes into account the remarks made during the WG-FSA 2013. The objective is to progress on modelling tools and to improve the estimation of current biomass. An update of the assessment of Dissostichus eleginoides using a CASAL model and a simple Petersen biomass estimate derived from tagging data are presented. The CASAL model structure is improved with sub-fisheries “deep” and “shallow”. Three scenarios are tested. B₀ is estimated at around 400 tonnes and B₂₀₁₃/B₀ at around 50%. With Petersen’s method, geometric mean stock abundance for D.eleginoides, averaged over all available estimates is 403 tons. Application of the harvest rate applied to D. eleginoides in Subarea 48.4 (γ = 0.038) gives yields of 15 tons. But biomass estimates are uncertain, the CPUE analogy method indicates a substantially higher biomass (2,798 tons). CASAL and Petersen estimates were based on tags released and recaptured only in the western part of Elan Bank. It is necessary to revise the design survey and to produce a further work on the assessment model. Maintaining the catch limit to 32 tons is suggested for expect a number of recaptures of 35 in 2014/15.