Variation in Geographical Distribution and Abundance of Larvae of Antarctic Krill, Euphausia superba, in the Southern Atlantic Ocean

Summary

The geographical distribution and annual fluctuations in abundance of Euphausia superba larvae, mainly calyptopis stages, were studied in 1976, 1978 and 1981 in the central Scotia Sea and in the Bransfield Strait region. Comparisons are restricted to January-March, since previous studies have shown that relatively few larvae occur earlier in the season. In 1981, larval abundance was highest in the open ocean of the central Scotia Sea and in the shelf region close to Elephant Island. Abundance was significantly lower in 1978 when only a few ‘rich’ catches were made northeast of the South Orkney Islands and in the Bransfield Strait. In 1976, Krill larvae occurred in fair numbers in both the Bransfield Strait and the northern Scotia Sea. The Bransfield Strait region appears to be a major spawning area for Krill. Spawning in the open ocean apparently varies from year to year, in both space and time, for which explanations are not yet available. The same holds for large fluctuations in the abundance of larval Krill.