CCAMLR

We present the beginnings of a compilation of a suite of physical and biological oceanographic data, and concomitant data on abundance and condition of some key zooplankton species and vertebrate higher predator species, collected at sea off South Georgia and from Bird Island between 1996 and 1999. We plan to use these data, some of which arise from the British Antarctic Survey's Core Programme, to develop multivariate indices of "ecosystem status". We expect that such indices will lead to an improved understanding of some cause-and-effect mechanisms that underlie the pronounced interannual variability that we observe habitually in many components of the South Georgia marine ecosystem. The indices may also contribute to CCAMLR's WG-EMM, the terms of reference of which include provision of advice on ecosystem assessment that combines information from dependant and harvested species, and from the environment, to provide holistic advice on ecosystem management.

Positions of commercial krill operation for 1980/81 season to 1998/99 season in the area to the north of South Shetland Islands were analyzed by using GLM (generalized linear model). Fishing season, the timing, and the longitude were significant factors to explain the variability of latitudes where operations were undertaken. Operations tended take place in the north in early 1980s, but from mid-1980 onwards, they tended to happen in the south, with exceptions of 1994/95 and 1995/96 seasons. Predicted latitudes of operation significantly correlated with Salp densities in the Elephant Island area (Spearman's rank correlation , p<0.05), but not with krill densities. This may be due to the intention of fishing vessels to reduce the salp in the products.

Scientific observations on fishes and salps incidentally caught during commercial krill fisheries by F/V Niitaka Maru were made from 3 January to 4 February 1999 in the vicinity of the South Shetland Islands. Among 74 net hauls quantitatively examined, only a total of 5 specimens of juvenile fishes belonging to three notothenioid species, Notothenia coriiceps, Chaenocephalus aceratus and Chaenodraco wilsoni were found in 4 trawl catches. On the contrary, salps were captured as by-catch in 69 hauls and those estimated value was 20 to 3560 ind./t of krill. By-catch fishes fed on Thysanoessa macrura and Euphausia superba was not found in their stomachs. Abundance of salps in krill catches could have been depended on the density of krill concentration. At least, the large incidental catch of salps (>2500 ind./t of krill) occurred in hauls with the low krill catch rates (