The structure and spatial distribution of Antarctic krill aggregations from acoustic observation in the South Georgia area

Results of acoustic surveys carried out in winter months of 2000 and 2002 demonstrate significant distinctions in spatial distribution patterns of krill in the northwestern and the northeastern parts of South Georgia area. The boundary between two areas is located at about 37°30/ W. It is shown that in winter months in the northwestern part where foraging areas of dependent predators are located is non-attractive to fishery . The observed grounds with krill density exceeding the threshold value 100 g/m2 determined as potential fishing grounds were located in the northeastern part of South Georgia.
Comparison of krill aggregations structure in the northwestern and the northeastern parts of South Georgia area allows to assume that dispersed aggregation (layer and irregular forms) much more suits to the foraging tactics of dependent predators than krill distribution in the form of dense swarms or patches, which on the contrary are attractive to the fishing fleet. The considered results show that not only krill biomass density, but also its availability determined by krill aggregations distribution, will be very important both to fishery and to dependent species,