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.
Mr Doug Cooper (CCAMLR Secretariat)