Champsocephalus gunnari stock status in the South Georgia area
ata of age composition and fishing effort for 1976/77-1987/88 were used to analyse stock status and TAC for C. gunnari. Stock estimates were obtained using VPA with the following variations: mean F, Gamma methods, Pope and Shepherd method, using F regression on fishing effort and method of average weighted F.
For 1986/87 the values obtained by different methods differed considerably from each other, from 120 thousand tonnes (regression method) to 213 thousand tonnes (Pope-Shepherd method). For TAC prediction the stock size value was obtained by VPA with variations using F regression methods. The recruitment was taken at the lowest possible level for all these years (400 million specimens). Catch-per-unit-effort was also taken at the lowest level.
TAC was calculated for three possible situations:
(a) Fishing intensity (F) in a predicted period was equal to the average value of fishing mortality:
(b) For the predicted period fishing intensity was at the level of that in 1987/88;
(c) For the predicted period fishing intensity was F0.1.
In the first two cases TAC=25-30 thousand tonnes and stock size does not change. For the third case TAC= 14-18 thousand tonnes and stock size increases. The analysis of the information shows that at the currently used value of stock size and even at the lowest possible recruitment levels and catch-per-unit-effort the present fishing regime does not lead to a decline in C. gunnari stock size.