Mapping deep-water benthic habitats around South Georgia

No abstracts are to be cited without prior reference to the author.

South Georgia lies on a small continental shelf with water depths of a few hundred meters. At the margins of this, the seabed rapidly declines to the ocean floor at depths between 3-4,000 m. The continental shelf supports numerous fish species within a complex ecosystem that has attracted much interest from commercial fishing. A significant longline fishery exists for toothfish (Dissostichus eleginoides), whereas both demersal and pelagic trawling has been used to target mackerel icefish (Champsocephalus gunnari). Although these species are managed sustainably within precautionary limits, the impact of these fisheries on the benthos is relatively unknown. Benthic species data now available from scientific observers working on commercial longliners have been analysed to map the location and relative abundance of different species around South Georgia. This has enabled areas of high diversity and biologically important species, such as deep-water corals, to be identified. Recent advances in charting the bathymetry around South Georgia using acoustic surveys now reveal the detailed topography of the slope and allow us to characterise species to specific features of the seabed. A number of statistical models have been developed to describe these relationships in more detail. With additional knowledge of the behaviour and specific location of fishing activities, areas of potential impact can be identified for fisheries management and species conservation purposes.