Composition and characteristics of ichthyofauna in pelagic waters of South Georgia (Subarea 48.3)
This paper presents the results of randomly stratified pelagic trawl census surveys conducted in Subarea 48.3. From 1984 to 1990 daily sampling stations aimed at studying the vertical migrations of some of the most abundant species were carried out during the six pelagic surveys. Horizontal distribution and length composition of fish, as well as the comparative distribution of krill and juvenile Champsocephalus gunnari were studied. The pelagic component of the ichthyocenosis in the subarea consisted of pelagic fishes (mainly Myctophidae), distributed at a depth range of 250 to 300 m, as well as demersal fishes in the pelagic stage of their life cycle. Catches contained both young and adult specimens of 42 species from 16 families. Numerically, catches were dominated by C. gunnari, Lepidonotothen larseni, Chaenocephalus aceratus and Gymnoscopelus nicholsi. Nototheniidae (12 species), Myctophidae (9 species) and Bathydraconidae (5 species) were the most common families. Adults and juveniles of some demersal species inhabited different areas, i.e. juveniles were distributed mainly in the south, whereas adults were found in the northern shelf area. Diurnal vertical distribution of young and adult fish was also different. Large fishes were most often taken near the bottom, while small ones were caught in the water column. The main food item (up to 60-80%) of both juvenile and adult fish taken by the sampling trawl in the water column was found to be krill. Aggregations of juvenile C. gunnari were observed only outside dense concentrations of Antarctic krill.