Krill distribution pattern due to water structure and dynamics near the South Sandwich Islands in January–February 2000 (Krill Synoptic Survey 2000)

There were carried out hydroacoustic, biological and oceanographic surveys in subarea 48.4 near South Sandwich Islands. The main water masses were revealed and their boundaries determined: waters of Antarctic Circumpolar Current, Weddell Sea and Secondary Frontal zone of Weddell Gyre. The schematic maps of geostrophic waters circulation are made. The joint analysis of environment parameters and krill distribution is carried out. There are determined three krill groups which differ each other by length frequency, maturity stages and waters inhabited. Distribution of the 1st krill group (juveniles 25-29 mm) well corresponds to meanders of Weddell Current to West of archipelago and distribution of the 2nd group (41 -47 mm) to Frontal Zone of Weddell Gyre. In small eddies on FZWG boundary takes place concentration of krill of the 3rd group (50-56 mm) transported there by ACC waters. Such concentrated schools are transported to South from East of archipelago, and may be mixed with krill of the 1st group. It is very probable that krill concentrated in stable eddies to East of archipelago may be kept there for a rather long time, maturation and spawning may take place. Newborn larvae may drift further providing krill recruitment for the range parts situated down the Current