On commercial significance of krill aggregations

We made an attempt to estimate krill commercial biomass density within the fleet operation areas and compare it with critical density values for marine animals feeding on krill. The results of acoustic investigation obtained in the Soviet trawler operation areas in Subareas 48.1-48.4 were used. We also analyzed commercial statistics data, including haul by haul data from Soviet trawlers numbering 22000 hauls for the period of 1986-1990 and those from Ukrainian trawlers for the period of 2001 and 2002 (2380 hauls).
In the course of the recent twenty years, krill has been fished in the areas with biomass density of at least 100 g/m2. This threshold value of krill commercial biomass considerably exceeds a critical value of krill density for aquatic animals feeding on krill and has been estimated at 24 g/m2 (Boyd, 2001). As is evident from comparison of above density values, the fleet and dependent predators will have different density niches.