Harvest Strategy Evaluation for School and Gummy Shark

Alternative harvest strategies for school and gummy sharks in waters around southeast Australia were evaluated in order to set annual Total Allowable Catches (TACs) for these species. The various strategies were compared in terms of their performance relative to the Ecological Sustainable Development objective. All strategies contain an estimator that analyzes fishery data, for estimating key quantities of interest to management, and a catch control law that uses assessment results to determine the TAC. Only harvest strategies based on the age-structured production model assessment approach are considered. The assessment accounts for the type of fishing gear used and the shark pupping process. Uncertainties involve assumptions about shark stock productivity, the extent of future TAC-related discarding, and tagging failures. Harvest strategy performances were very sensitive to interactions between school and gummy sharks. Ignoring such interactions may cause non-target species' recovery ability to be greatly overestimated. None of the strategies considered performed well in terms of school shark recovery. Gummy shark catches may need to be reduced in order to avoid TAC-related school shark discards.