Updated south coast rock lobster stock assessments for 2009

Working Paper


Permanent link to this Item
Journal Title
Link to Journal
Journal ISSN
Volume Title

University of Cape Town

This document is submitted in response to the requirement that “simple routine updated assessments (likely no more than core reference set models used in the OMP testing refitted taking a further year’s data into account)” be tabled every year an OMP is in operation for a fishery (MCM, 2007) This document reports such updated stock assessments for the South Coast rock lobster fishery. Essentially two further years’ CPUE and catch-at-length data are available since the assessments upon which OMP testing was based were carried out in 2008 (see Johnston and Butterworth 2008a). Although Johnston and Butterworth (2008a) initially presented stock assessment results for a wide range of models, only Models 3 and 4 were used as a final Reference Set in final OMP deliberations. Updates of Models 3 and 4 are thus presented here. To recap: Model 3 – assumes time-varying selectivity using the MARAM method Model 4 – assumes time-varying selectivity using the OLRAC method. Besides data updates, a further update to these assessment models is that the period for which recruitment residuals are estimated is extended from 1974-1997 by two further seasons to 1974-1999.