Distribution of Antarctic krill concentrations exploited by Japanese krill trawlers and minke whates

The distribution of krill (Euphausia superba) concentrations derived from Japanese krill fishing and minke whaling (Balaenoptera acutorostrata) data was investigated in relation to bottom topography, sea-ice and hydrographic features. Data were from the Indian, Pacific and western Atlantic sectors. In early summer (December) the areas of operation for both fisheries were affected by the latitudinal position and shape of the pack-ice edge. Harvesting was frequently conducted in the vicinity of a more southerly positioned pack-ice edge. Whaling was also undertaken in the embayments created by the pack-ice edge. When the ice-edge was at its southernmost limit (January- March), krill fishing data indicated that harvestable areas were associated with the continental and insular shelf breaks, not the pack-ice edge. Minke whaling data also suggested that not only sea-ice but also topographical features such as the continental shelf break and various banks may be important factors affecting minke whale distribution. Krill harvesting areas in the vicinity of the shelf breaks were often coincident with hydrographic fronts. These frontal features, by accompanying convergence or by coupling with krill specific behavior, were speculated to induce the formation of krill concentrations. The concentration of E. superba around a bank on the Ross Sea shelf is suggested on the basis of extreme high concentration of minke whales and their food composition