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    Diet composition and observations on reproduction of Champsocephalus gunnari in Subarea 48.3 in March/April 1996, Dr Eduardo Holmberg survey

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    Document Number:
    WG-FSA-96/28 Rev. 1
    Author(s):
    Marschoff, E., Barrera-Oro, E., Casaux, R.
    Agenda Item(s)
    Abstract

    The diet composition of the icefish Champsocephalus gumari caught in the Subarea 48.3 in March/April 1996 was analyzed using Frequency of occurrence (F%) and coefficient "Q" (%) methods. Krill was by far the main food around South Georgia and Shag Rocks (F= 85%, Q= 99%). Other prey items, known as an important alternative food in years of krill scarcity, were ingested only occasionally (Themisto gaudichaudii, F= 1 8%, Q= 1 % at SG; mysids, F= 11 %, Q= 1.1 % at SR) or in negligible amounts (Thysanoessa sp.). Many empty stomachs (56%) were found in the sampling area, in levels even higher than those reported for the 1991 and 1994 years of krill shortage. The analysis of the ovarian maturation stages showed that a high proportion of the mature fish sampled (79 %) were 1996 spawners, a fact which may be related with a large availability of food (= krill). It is suggested that krill was present in the region in levels equivalent to the historical years of high abundance.

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