The Northeast Arctic cod stock's place in the Barents Sea ecosystem in the 1980s: an overview

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Mehl, Sigbjørn (1991)

Just after World War II the size of the Northeast Arctic cod (Gadus morhua) stock was about 6 million tonnes, but at the beginning of the 1980s the stock had been reduced to 1 million tonnes, due mainly to the excessively high fishing-mortality. Nevertheless, the stock produced strong year classes at the 0-group stage in the relatively warm period 1983-1985. At the same time, individual growth in the cod stock was good, and in 1986 the stock size increased to over 1.5 million tonnes. However, the cod preyed increasingly on the capelin (Mallotus villosus) present, and by the end of 1986 the capelin stock was seriously depleted. The cod compensated for the loss of capelin by preying more intensively on other food items, including smaller cod. Cannibalism increased by a factor of three from 1984 to 1986, and this is one important reason why the 1984 and 1985 year classes did not recruit to the fisheries as expected. Individual growth was dramatically reduced, and the average fish weight decreased by about 50% in most age groups. Because the quotas are in tonnes, more fish than expected were caught. This resulted in serious management problems and led to reductions both in stock size and quotas compared to the optimistic prognosis of the mid-1980s.
  • References (24)
    24 references, page 1 of 3

    Bergstad, 0. A , , J~rgensen,T . & Dragesung, 0. 1987: Life history features and ecology of the gadoid resources of the Barents sea. Fish. Res. 5, 11%161.

    Bogstad, B . & Mehl. S. 1990: The consumption rate of Northeast Arctic cod - a comparison of gastric evacuation models. ICES CM 1990JG: 22.

    dos Santos, J . 1990: Aspects of the eco-physiology of predation in Atlantic cod (Cudus morhua L.). Dr. scient thesis, University of T r o m s ~ ,1990. 116 pp.

    Hylen. A , , Loeng. H . . Mehl. S. & Nedreaas. K . 1989: Estimates of stock size of cod, haddock, redfish and Greenland halibut in the Barents Sea and the Svalbard area autumn 1988. ICES CM 1989/G: 39.

    Hylen, A . & 0ynes. P. 1986: Result of stratified trawl surveys for shrimps (Pandalus borealis) in the Barents Sea and Svalbard region in 1986. ICES CM 1986/K: 34.

    ICES CM 1985: Report of the Arctic Fisheries Working Group. Copenhagen. 26 September-3 October 1984 ICES CM 1985/ Assess: 2 .

    ICES CM 1986a: Report of the Arctic Fisheries Working Group. Copenhagen. 25 September-2 October 1985. ICES CM 1986/Assess: 4 .

    ICES CM 1986b: Report of the Atlanto-Scandian Herring and Capelin Working Group. ICES CM 1986/Assess: 7 .

    ICES CM 1987: Report of the Working Group on AtlantoScandian Herring and Capelin. Copenhagen. 27-31 October 1986. ICES CM 1987/Assess: 8.

    ICES CM 1989a: Preliminary report of the International 0- group fish survey in the Barents Sea and adjacent waters in August-September 1989. ICES CM 1989/G: 40.

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