Environment-krill relations in the South Georgia marine ecosystem

Interannual variability in the Southern Ocean ecosystem has long been noted and physical factors appear to dominate the dynamics. There are, however, few ecological time series available to assess this variability and it is only recently that physical datasets have been generated for the Southern Ocean. In this study, time series of krill abundance (CPUE) indices were derived from Soviet fishing operations in the northeastern Scotia Sea around South Georgia for the period from 1974 to 1992. These indices were examined in relation to the variation in the physical environment. There are links between the ice, ocean and atmospheric components of the system, and there are also correlations with CPUE data. The CPUE index generally agrees with other data which give direct or indirect indications of krill availability, suggesting it can be a useful index for some regions. Associations with ice-edge position and atmospheric components were only expressed strongly in years of extreme conditions. The correlation with water temperature was more consistent, supporting suggestions that the variability in krill abundance around South Georgia is strongly influenced by the oceanographic regime of the Scotia Sea.

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