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

• Published in: Antarctic Science
• Main Authors: Siegel, V., Bergström, B., Mühlenhardt-Siegel, U., Thomasson, M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2002
• Subjects: Geology; Ecology, Evolution, Behavior and Systematics; Oceanography; Elephant Island; Antarctic Science
• Online Access: http://dx.doi.org/10.1017/s095410200200072x; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S095410200200072X

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 R 1 = 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.