Preliminary assessment of Patagonian toothfish in Subarea 48.4

To date, the stocks of toothfish in Subarea 48.4 have been divided, for assessment purposes, into northern and southern components. The northern component is assessed as a single species of D. eleginoides whilst the southern component is assessed as a combination of D.eleginoides and D. mawsoni. Both species are caught throughout Subarea 48.4 although D.eleginoides are predominantly caught in the north, whilst D. mawsoni are mainly caught in the south. CCAMLR WG-FSA 2012 concluded that species specific assessments, covering the whole of the subarea, would be a more appropriate method for assessing the stocks than the existing area based, species combined approach. This paper describes the revised assessment of D. eleginoides in Subarea 48.4. The main changes to the assessment are: the removal of D.mawsoni data and the inclusion of D. eleginoides for the southern region; revision of tagging data for the full time series; re-estimation of the maturity ogive; changes to the assumed selection pattern and revised growth assumptions. The revised assessment is compared with the previous assessment for this stock. Data deficiencies and areas for future work to further improve the assessment are identified.