The integrated Antarctic expedition of the YugNIRO in the season of 1989–1990: main results of the ichthyological studies

From the field material collected on the YugNIRO integrated expedition in the Indian Ocean sector of the Antarctic in the season of 1989-1990, information is presented in this paper on ichthyofauna, size–weight composition and main parameters of the biological state of the more abundant fishes taken on the shelf of Antarctica, at Ob and Lena Seamounts (referred to as Banks in the Russian usage), and in the zone of the Southern Polar front.
In the shelf area, of Cooperation Sea, localities of elevated bioproductivity were pinpointed, mixed-species aggregations of Chaenodraco wilsoni and Pseudotrematomus eulepidotus were found in those places. Both seasonal and diurnal trends of the species cooccurrence (i.e. the varying species ratio in the aggregation) were brought out. The bulk of fish examined was made up of matte individuals with gonads in postspawning stages of maturity. Krill was the chief component in the diet of fish.
From census survey by trawl and acoustic means, simultaneous ichthyomass was estimated on Rise "6230" (Storegg Bank), where some 30 thousand tons of fish concentrated over an area of some 50 square miles. Census surveys were carried out also in other areas of the Cooperation Sea shelf and in the subantarctic zone of the Indian Ocean (Ob and Lena Banks).