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    Steepness for Antarctic toothfish (Dissostichus mawsoni) based on life history

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    Document Number:
    WG-FSA-14/32
    Author(s):
    M. Mangel, J. Brodziak and G.M. Watters (USA)
    Submitted By:
    Mr Doug Cooper (CCAMLR Secretariat)
    Agenda Item(s)
    Abstract

    Although steepness is typically considered a convenient re-parametrization of a stock-recruitment relationship, it is deeply rooted in the biology of each species.  Furthermore, specifying steepness and other life-history parameters such as natural mortality and growth rates fixes reference points that are commonly used in fisheries management.  Thus, one cannot pick an arbitrary value of steepness in a stock assessment.  We take the first step towards a consistent treatment of steepness for Antarctic toothfish by showing how to compute a frequency distribution of steepness based on life-history parameters.  We also highlight what the next steps should be – both theoretical and empirical – for improving estimates of steepness and their use in stock assessments.