A YIELD-PER-RECRUIT MODEL FOR SEQUENTIAL FISHERIES AND ITS APPLICATION IN EVALUATING THE MANAGEMENT STRATEGY OF CHANGING INCIDENTAL INSHOREFISHING MORTALITY

Yield-per-recruit (YPR) analysis is commonly used to test alternative management strategies when historical information on recruitment for t he fish population being studied is limited. Like many other types of fisheries models, a primary assumption implied in YPR models is random ness in the distribution of fish and effective fishing efforts through out the fishery. However, in practice, this assumption is rarely satis fied because spatial distribution of many fish populations is not rand om and the deployment of fishing efforts tends to target the area wher e fish of commercial sizes are abundant. In this study, we propose a Y PR model for sequential fisheries that incorporates size-dependent dif ference in spatial distributions of fish and differences in selection patterns of fishing gears between inshore and offshore waters. We appl y the proposed YPR model to evaluate the management strategy of changi ng incidental inshore fishing mortality for simulated fisheries based on redfish, Centroberyx affinis, and tiger flathead, Neoplatycephalus richardsoni, along the New South Wales coast (Australia). This study d emonstrates a linkage between the fishing mortality on inshore grounds and YPR for both redfish and tiger flathead. Changes in YPR resulting from changes in the inshore incidental fishing mortality were more pr onounced for redfish which displays a more consistent size-dependent o ffshore distribution.