REPORT OF THE UK GROUNDFISH SURVEY AT SOUTH GEORGIA (CCAMLR SUB-AREA 48.3) IN JANUARY 2009

In January 2009 the UK undertook a bottom trawl survey of CCAMLR Sub-area 48.3 on the FV Sil. A total of 71 random and representative 30 min tows were made giving good geographic coverage. The estimated mean biomass of Mackerel icefish (Champsocephalus gunnari) calculated using 10 strata, updated sea-floor areas and adjusting for the low headline height of the trawl (see CCAMLR WG-FSA (2003)) was 31,753 t with a lower 1-sided CI at 18,904 t. Catches of icefish across the region were dominated by a single length class whose mean length varied between South Georgia and Shag Rocks and were assumed to be 3+. Very few juvenile fish were observed except in the south eastern sector of the South Georgia shelf. Icefish diet was dominated by the amphipod, Themisto gaudichaudii with very low levels of krill, Euphausia superba found. This was likely to have been a result of the anomalous environmental conditions experienced at South Georgia during 2009. Biomass estimates and length frequencies are reported for other non-target species. There was evidence that the large cohort of juvenile Patagonian toothfish (Dissostichus eleginoides) observed an all surveys since 2003 had moved into deepwater and was no longer present at depths <300m. The estimate of biomass of the marbled rockcod, Notothenia rossii was considerably higher than estimated from the 2008 survey data.