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    Demography of Antarctic krill in the Elephant Island area (Antarctic Peninsula) during austral summer 2001

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    Número de documento:
    V. Siegel (Germany), B. Bergström (Sweden), U. Mühlenhardt-Siegel (Germany) and M. Thomasson (Sweden)
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    A net sampling survey was carried out for krill in an established standard station grid around Elephant Island during 27 January to 4 February 2001. Results show a spatial separation of the juvenile and the spawning stock. The station grid was extended to the south, where a large proportion of small size classes, one year old juvenile krill was found. Krill density was significantly higher than during the past years (between 198 and 230 krill 1000 m-3 , i.e. between 40 and 46 m-2 or 11.3 g m-2). The proportional recruitment index for the entire survey area for the 1999/2000 year class was R1 = 0.573, and the absolute index was RI1 = 131.4 * 1000 m-3 , which is among the highest values for the past 20 years. The high krill abundance and the high recruitment index reflect the end of a succession of years with poor recruitment success. The maturation index (G, according to gravid stages), which is discussed as an indicator for a successful spawning season, was G = 0.99, indicating an early initiation of the spawning season. 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.