Report of the Workshop for the International Coordinated Survey in conjunction with CCAMLR-2000 Survey

Vessels from Japan, Republic of Korea, Peru and the USA had participated in the conduct of five acoustic/oceanographic surveys from late December 1999 and to early March 2000 in conjunction with CCAMLR 2000 survey. Time-series acoustic data from the coordinated survey were analyzed. Excluding the highest and lowest surveys, biomass densities on three remaining surveys were 49.2 g m-2 (CV 19.5 %), 39.5 g m-2 (CV 15.2 %) and 43.0 g m-2 (CV 14.1 %) over a nine-week period. Maps of biomass density for each of the surveys are presented, and examination of these maps suggests three consistent area of high krill density; near the east end of Elephant Island, mid-way between Elephant and King George Islands, and near Cape Shirreff on the north side of Livingston Island. It appears that highest densities of krill move closer to the shelf break as the season progresses. This apparent movement is complemented by a change in the demographic structure of the population. The smaller size modes disappear and krill are more sexually mature later in the summer. If the lowest estimate is treated as the result of measurement errors, then the consistency between the four other surveys suggests low variability in krill biomass north of South Shetland Islands throughout the summer of 1999/2000. Future work analyses could include analyses of patch sizes and densities along transects as a means of investigating variations in krill availability to predators under conditions of constant krill biomass density. Additional oceanographic observation together with satellite-derived information could be jointly analyzed to explain variations in krill abundance and dispersion patterns.