CCAMLR

Some peculiarities of spatial and temporal variability of the glassfish distribution on the South Georgia Island shelf relative to environmental conditions have been revealed from summarizing and analysis of hydrographic and commercial fishery and biological data for 1986-1987.

Scales and otoliths were collected from 304 specimens of the Antarctic fish Notothenia gibberifrons. When interpreted separately, only 25% of scale and otolith readings agreed. When a scale and otolith from a single simultaneously, 75% of readings agreed. of otolith readings changed between specimen were interpreted 60% of scale readings and 30% separate and simultaneous interpretations. Estimates of age tend to be lower when made from scales. Predictions of yield per recruit utilising age data derived from scales are approximately 30% greater than predictions utilising age data derived from otoliths.

This study focuses on the Chamsocephahus gunnari stock around South Georgia. The principle aims are, first, to assess current and past biomass and recruitment levels and, second, to analyse the relationship between the spawning stock and number of recruits. A conventional VPA and an ad hoc tuning method are used to estimate biomass levels and fishing mortality for the period 1971/72 to 1988/89. VPA-estimates of recruitment levels are used to investigate the degree of variability and the likely statistical distribution of recruitment. Data obtained during the UK/Polish survey around South Georgia in March 1989, were included in the study.
Results indicate that the current biomass level of the C. gunnari stock around South Georgia is only about 25% of the estimated peak biomass and that catch levels observed in recent years cannot be sustained. There is no clear relationship between the size of the spawning stock and recruitment, which is highly variable