ANALYSIS OF ICE-FISH (CHAMPSOCEPHALUS GUNNARI) SPATIAL DISTRIBUTION FOR OPTIMIZATION OF THE BOTTOM TRAWL SURVEY SAMPLING

The spatial distribution characteristics of ice-fish in the near-bottom layer are analyzed using the acoustic data obtained in the South Georgia area during the Russian bottom trawl surveys 2002. Acoustic and trawl density samples obtained in the near-bottom layer covered by trawl survey are compared. It is shown the possibility to estimate the bottom trawl efficiency. The high heterogeneity of horizontal and vertical fish distribution in the near-bottom layer of the survey area is shown. Influence of this fish distribution heterogeneity on trawl surveys efficiency and reliability is analyzed. In addition, the author discuses the results of bottom trawl surveys carried out in the South Georgia area during season’s 2000 and 2002. It is shown, that observed inter-seasons and inter-vessels differences between fish biomass estimates from bottom surveys may be to a considerable degree stipulated by heterogeneity of fish distribution in the near-bottom layer relative to the fishing gear operation zone (Russian trawl HEK-4M and UK trawl FP120) and the trawl station location rather than by the variability of the stock state.