On assessing the size of the humped rockcod stock (Notothenia gibberifrons) in Subarea 48.3

An adaptive approach was used to assess the Notothenia gibberifrons stock in Area 48.3. It is demonstrated that when tuning the VPA using abundance indices from trawl surveys it is imperative to estimate the catchability coefficient. This parameter was equal to 0.326 to 0.635.
An adaptive approach in this case involved using a target function in the form of the sum of square deviations in logarithms of observed and calculated biomass indices and resulted in an estimate of from 21.5 to 42.1 thousand tonnes for N. gibberifrons biomass in the 1989/90 season. It is thus possible to suggest a TAC of 1.9 to 2.7 thousand tonnes.
A similar approach is recommended for assessing the stock of other commercial species in this area.