Standing stock, biology, diet and spatial distribution of demersal finfish from the 2003 US AMLR bottom trawl survey of the South Shetland Islands (Subarea 48.1)

The United States Antarctic Marine Living Resources (U.S. AMLR) program has conducted bottom trawl surveys of the South Shetland Islands (Subarea 48.1) during the 1998, 2001, and 2003 austral summers. Information on species and size composition, abundance, spatial distribution, and dietary patterns from the 2003 survey is presented. The spatial distributions and standardized densities for demersal finfish species have remained relatively consistent across all surveys. Shelf regions of importance for krill, fish, and benthic feeding guilds based on stomach content analysis demonstrate the most important feeding areas lie to the west and north of Elephant Island and to the north of King George Island greater than 200 meters. Estimates of total stock biomass from these surveys were computed for eight species: Champsocephalus gunnari, Chaenocephalus aceratus, Chionodraco rastrospinosus, Gobionotothen gibberifrons, Lepidonotothen larseni, Lepidonotothen squamifrons, Notothenia coriiceps, and Notothenia rossii. The standing stock for most species has fluctuated, with no signal of substantial year classes or significant recruitment for any species. Although standing stocks of G. gibberifrons remain the largest relative to all other species, there appears to be a decline in biomass. The overall abundance of finfish in the South Shetland Islands has yet to reach a level at which commercial exploitation would be advisable.