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Demography of krill in the Elephant Island area during summer 2001 and its significance for stock recruitment

Published online by Cambridge University Press:  27 April 2004

V. Siegel
Affiliation:
Seafisheries Research Institute, Palmaille 9, D-22767 Hamburg, Germany
B. Bergström
Affiliation:
Kristineberg Marine Biological Station, Fiskebäckskil, Sweden
U. Mühlenhardt-Siegel
Affiliation:
German Centre of Marine Biodiversity, Martin-Luther-King Platz 3, D-20146 Hamburg, Germany
M. Thomasson
Affiliation:
Kristineberg Marine Biological Station, Fiskebäckskil, Sweden

Abstract

A net sampling survey was carried out for krill in a standard station grid around Elephant Island during 27 January to 4 February 2001. In comparison with recent years the station grid was extended south, where a large proportion of small size classes, one-year-old juvenile krill was found. Results show a spatial separation of the juvenile krill and the spawning stock, Krill density was significantly higher than during the past years (229 krill 1000 m−3 or 13.0 g m−2). The proportional recruitment index for the entire survey area for the 1999/2000 year class was R1 = 0.573, which is among the highest values recorded during the past 20 years. The maturation index (based on the proportion of gravid stages) was G = 0.99, indicating an early initiation of the spawning season. The results indicate a turning point after a succession of years with poor recruitment success and low stock biomass. This is thought to be the first step for a successful spawning event and a later potential recruitment success of the 2000/01 year-class. The spatial extent of the station grid is discussed in the light of a representative coverage of the stock and the estimated recruitment index.

Type
Life Sciences
Copyright
© Antarctic Science Ltd 2002

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