A bayesian model for European hake with priors based on life history invariants.

Abstract

European hake is a main target fish for the fleet operating in Atlantic waters, although there are many biological unknowns that compromise the quality of the current assessment and scientific advice. Growth, natural mortality and reproduction are main biological processes required to develop population dynamic models for assessment purposes. Currently, the parameters defining these processes such Von Bertalanffy asymptotic length, M, L 50% of maturity or Beverton-Holt steepness are estimated outside the model and set as constants. Population dynamic bayesian models provide a suitable platform to develop solutions to this kind of problems since Bayesian models allow using additional knowledge from similar species in the form of the priors. Informative priors for biological key parameters have been developed based on available data for Northern hake combined with information from other hake species all over the world. This information is analyzed on the light of ecological theory for life history invariants (LHI) to produce the required priors. LHI figures are relatively constant among similar species. Information from other hakes may help to fill the gap in assessment and management of European hake. The pros and cons of using these informative priors to improve hake assessment are finally discussed.