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    The use of predator-derived krill length-frequency distributions to calculate krill target strength

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    Numéro du document:
    WG-EMM-00/42
    Auteur(s):
    K. Reid and A.S. Brierley (United Kingdom)
    Point(s) de l'ordre du jour
    Résumé

    The relationship between krill abundance and predator performance is fundamental to an ecosystem based approach to resource management. We propose a method using krill sampled from the diet of predators to provide a length-frequency distribution of krill at times when it is possible to run automated ship-board acoustic systems but not to conduct scientific netting, i.e during logistic/re-supply operations. This will allow a robust estimate of krill abundance to be estimated from acoustic data. Changes in the length-frequency distribution of krill over a period of few weeks produced a 10 % difference in TS whereas simultaneous samples from predators and nets produced only a 1 % difference, illustrating the need for simultaneous length-frequency data. By integrating data from land-based predators directly with automated on board data collection systems it will be possible to gain important estimates of krill biomass at times of the season hitherto unavailable from ship-board scientific surveys.