Krill ( Euphausia superba ) recruitment indices from the western Antarctic Peninsula: are they representative of larger regions?

Abstract

This study presents data on krill demography west of the Antarctic Peninsula covering many years since 1982. The recruitment indices are compared with those for other mesoscale study regions collected over the last 25 years. We use these data to investigate whether results from such mesoscale surveys are representative of large-scale stocks or regional populations. Generally, the proportional recruitment indices for 1- (R1) and 2-year-old (R2) krill differ substantially between years for a given area. However, indices were in conformity with the results from other regional scientific surveys. Recruitment indices showed a significant correlation for age-class 1 krill between scientific surveys from the northern Bellingshausen Sea, the Elephant Island area and South Georgia. The correlation becomes weaker for R2 recruitment indices. There was no correlation between krill recruitment indices from Atlantic and Indian Ocean survey sites. Problems of single-year outliers from Elephant Island are discussed, as well as the problem of "undersized" length classes of the age-1 group that occur in the samples of some years.