Population subdivision and distribution of Euphausia superba in the region of the Antarctic Peninsula and adjacent waters in relation to fishery development

Analysis of original and literature data for the past 10 years pertaining to the region -of the Antarctic Penunsula and adjacent waters points to a relationship between the distribution of krill and the waters of two major circulation systems - those of the Weddell Sea and the Bellingshausen Sea inhabited by separate subpopulations of the species. The latter are predominant in the region while the proportion of the Weddell Sea krill increases eastward, primarily in the Bransfield Strait but also off the Mordvinov Island. Seasonal coastward migrations (Siegel's suggestion) may actually result from the fact that waters of each of the two major modifications carry out krill into the eastern part of the region at different times. Isaacs-Kidd trawl surveys yielded krill biomass values of 1233±41% and 1708±30% thousand tons in March and December-1984 respectively for the area south of 60°S between 60 and 52°W. The frequency of occurrence of krill aggregations in the area between 75 and 52°W was estimated. For this area, the 1984 survey data yielded krill biomass estimates of 3.27 to 7.89 million tons.