Preliminary assessment of toothfish in Subarea 48.3

As with the 2009 assessment of Subarea 48.3, there is still uncertainty as to why there were high numbers of the 2001 cohort in commercial catches in 2009 onwards.  It is likely that it is due to a combination of a strong 2001 cohort and a change in selectivity for the commercial fleet, but it has not been possible to determine the relative importance of each explanation.

Median log-normal recruitment suggests a long-term yield of 3 200 t.  If year class strengths have been low since 1994 and continue for the next 35 years then appropriate long -term yields could be as low as 975 tonnes.  This scenario is highly unlikely as survey data from 2010 and 2011 suggest a strong 2007 cohort, and survey data from 2004 to 2008 suggest a strong 2001 cohort.

Model projections, evidence of cohort strength from the surveys and the stabilisation of both SSB and CPUE that a long-term yield in the region of 2 000 tonnes would be appropriate, at least until catch-at-age data can confirm the strength of the 2007 cohort.