Statistical Catch-at-Length Assessment of S. fasciatus in Unit 3

An update of the 2011 Rademeyer and Butterworth SCAL assessment is presented. This incorporates some refinements of the previous methodology. Results with a deterministic stock-recruitment relationship are poor in not admitting a realistic estimate of survey catchability q. However, if the possibility of occasional large recruitments is introduced, the model fits the survey estimates of abundance better and a realistic estimate of q is obtained. As estimates of the depletion (B/K) of the resource vary considerably, possibly the best approach to management in the shorter term would be by setting catch limits based on annual replacement yield (RY) estimates, as these are reasonably robustly estimated at about 5000 tons.