The 2007 age-structured production model assessments and projections for the South Coast rock lobster resource-routine update using Pope's approximation model fitting to catch-at-age data including scenarios for time-varying selectivity

Abstract

The assessment conducted in 2006 (WG/06/06/WCRL3) has been routinely extended (except that the Baranov equation has been replaced by Pope’s approximation), taking account of a further year’s catch, CPUE and catch-at-age data. The observed CPUE shows a slight decrease for 2005 (2005/06 season). The sustainable yield estimates are generally very similar to those for the 2006 assessment, although estimates of current biomass levels relative to K increase. The Reference Case (RC) scenario suggests that a TAC of a little less than 330 MT or less would be appropriate to prevent biomass decline in the future. The other four scenarios reported suggest higher values than this, ranging from 350 MT to 405 MT. Spawning biomass trends over the last 10 years are downward for all the models considered.