Observations of demersal fish, benthic communities and seafloor composition of the Southern Ocean Atlantic sector from the ICEFISH 2004 cruise

A multi-disciplinary research cruise in the Atlantic sector of the Southern Ocean was conducted during the 2004 austral winter as part of the International Collaborative Expedition to collect and study Fish Indigenous to Sub-antarctic Habitats (ICEFISH). Sampling during the ICEFISH cruise included demersal finfish, benthic invertebrates, and information of seafloor composition. The objectives of the cruise included Antarctic fish and invertebrate biochemical, molecular and physiological, ecological and population genetics research. Trawling was conducted within the CCAMLR Convention area at Shag Rocks, South Georgia, the South Sandwich Islands, and Bouvetoya Island from 5 June to 30 June, 2004. A description of demersal finfish and benthic invertebrate collections, distribution, and composition from each island group is presented, including some preliminary information on the seabed composition of shelf areas. The total number of finfish specimens recorded within the Antarctic convergence during the ICEFISH cruise trawl deployments was 9105 specimens of 29 species.
A wide contrast in finfish and invertebrate species composition between island groups was observed, with the greatest differences between the South Sandwich Islands and Bouvetoya, where the isolation of the latter island likely played a role in the different community structure. Due to mixed gear selectivity and possible avoidance, it was not feasible to make quantitative estimates of finfish abundance. However, using data from the Blake trawl, estimates of benthic invertebrate densities by station were computed and maps generated that provide information on benthic communities.