Seasonal growth and mortality of Euphausia superba in Admiralty Bay, South Shetland Islands, Antarctica

• Published in: ICES Journal of Marine Science
• Main Authors: McClatchie, Sam, Rakusa-Suszczewski, Stanislaw, Filcek, Krzysztof
• Format: Text
• Language: English
• Published: Oxford University Press 1991
• Subjects: Articles; South Shetland Islands; Admiralty Bay; Antarc*; Antarctica; Euphausia superba
• Online Access: http://icesjms.oxfordjournals.org/cgi/content/short/48/3/335; https://doi.org/10.1093/icesjms/48.3.335

The mean size of adult and juvenile Euphausia superba in populations sampled during 1979–1986 in Admiralty Bay, South Shetland Islands, Antarctica shows a sinusoidal seasonal oscillation: mean krill size is reduced in winter. This has previously been interpreted as evidence of negative growth. Monthly total mortality was highest over winter, between July and October: there was notable interannual variability. We suggest that the winter-time decrease in mean krill size in Admiralty Bay results from predation reducing the numbers of larger, but less abundant krill, at a time when juvenile krill spawned the previous summer are recruiting to the population. This mechanism can explain the seasonal oscillation of mean krill size, without invoking negative growth.