Report on progress with refined hake assessment

Rademeyer, Rebecca A; Butterworth, Doug S

Report on progress with refined hake assessment

Working Paper

2009

Publisher

University of Cape Town

Department

Marine Resource Assessment and Management Group

Faculty

Faculty of Science

Abstract

Work is in progress on developing refined Operating Models for the hake resource to form the basis for the simulation testing of the next OMP due for adoption late in 2010. The primary form of model used is likely to be an extension of the area-specific selectivity-based approach used in 2006 (i.e. using changes in selectivity by area rather than explicit movement models to reflect changes in hake distribution with age). Two key new features, as recommended by the International Stock Assessment Workshop held in December 2008, are accounting for gender differences (because male and female hake grow at different rates, confounding the interpretation of length distribution data if this is not taken into account), and fitting directly to age-length data rather than to derived age distributions to account properly for biases that otherwise enter evaluations. We attach a DRAFT on the associated assessment paper currently under development. Note that this is NOT final, either in terms of editing or (preliminary) results shown, but is provided now to FACILITATE FEEDBACK. The primary task of the international stock assessment workshop taking place over November 30 to December 4 will be to review progress with the development of Operating Models and make recommendations for their finalisation early in the new year. Towards this end, work must now be sharply focussed to ensure that results of analyses to be tabled at the start of that workshop are as informative as possible. Accordingly feedback is requested from DWG members and observers (and will also be requested of the three-person international panel) on the following:

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