Zonation of demersal fishes off Anvers Island, western Antarctic Peninsula

摘要

The Antarctic fish fauna from outer continental shelf/upper slope depths is under-sampled compared to that of the inner shelf, and there are limited quantitative data available on absolute abundance and taxonomic change with depth. A photographic survey of demersal fishes was conducted along a depth-gradient of 400-2099m on the outer shelf and upper slope west of Anvers Island, Palmer Archipelago. A total of 1490 fishes were identified at least to the family level. Notothenioids composed 52.7% of absolute abundance and non-notothenioids 47.3%. The most abundant families were Nototheniidae (39.4%), followed by Macrouridae (28.9%), Zoarcidae (16.9%), and Channichthyidae (12.1%). The most abundant species were the notothenioids Lepidonotothen squamifrons (30.5%) and Chionobathyscus dewitti (11.7%), and the non-notothenioid Macrourus spp. (29.5%). The absolute abundance of all fishes peaked at 400-599 m. Depths of maximum abundance were 400-599m for L. squamifrons, 700-1499m for Macrourus spp., and 900-1499 for C. dewitti. At 700-999m the abundance shifted from primarily notothenioids to the non-notothenioids Macrourus spp. and zoarcids. Fishes of the outer shelf and upper slope are not provincialized like those of the inner shelf and are circum-Antarctic.