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    Diet composition of Champsocephalus gunnari in Subarea 48.3, Dr Eduardo Holmberg survey, February/ March 1994

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    Document Number:
    WG-FSA-94/27
    Author(s):
    E. Barrera-Oro, R. Casaux and A. Roux (Argentina)
    Agenda Item(s)
    Abstract

    The diet composition of the icefish Champsocephalus gunnari caught in the Subarea 48.3 in February/March 1994 was analyzed using the frequency of occurrence (%) method. Krill (Euphausia superba) followed by the amphipod hyperiid Themisto gaudichaudii were the main prey items at South Georgia and Shag Rocks; fish were found in the stomachs more frequently than in past seasons around South Georgia, in parallel with the virtual absence of mysids and Thysanoessa spp.. Krill was available for fish in common levels, equivalent to those of previous years (e.g. 1985, 1992). However, high proportions of empty stomachs were found at South Georgia and Shag Rocks, close to the values reported for the 1991 year of krill "shortage". Besides, the tentative analysis of part of the samples using the coefficient Q (%) showed a greater importance of T. gaudichaudii with respect to krill. It is possible that the inconsistencies found between the results obtained by both methods are due to a particular spatial distribution of krill in the area in the period of study, but no previous data are available for comparison. No krill aggregations were found in the region by acoustic methods in the 1994 summer season; a fact that might be related with a significant change in surface temperature observed during the cruise.

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