MBE702 Seminar Evaluation: Halie O'Farrell
Comparing shark harvest control rules to potential biological removals when determining total allowable catches
The Magnuson-Stevens Fishery Conservation and Management Act requires fisheries management councils to avoid overfishing by setting total allowable catch (TAC) limits. Currently, shark species’ TACs are set by estimating the relative abundance and projecting forward 20 years under various catch levels while accounting for uncertainty. The TAC is the catch level at which there is a 70% probability that the stock will not be overfished in 20 years. While the use of projections is an established method used for many fish species, it requires data on fisheries history, abundance trends and many life history parameters and involves running complex models with a long computing time. In a climate where more stock assessments and management decisions are being requested in less time with fewer resources, a simpler, more efficient method for determining TACs is needed. Management of protected marine mammals utilized the potential biological removals (PBR) approach to set limits. PBR requires little information and can be computed quickly. Because sharks have a similar life history to marine mammals we explore the possibility of using the PBR method as a more efficient method of establishing TACs. For the purposes of this exploratory work, shark species were limited to those assessed and managed in the south east United States and by the International Commission for the Conservation of Atlantic Tunas (ICCAT). TAC values were extracted from the latest stock assessments for each species, in addition to the information required to calculate a PBR. TAC and PBR values are compared to determine whether the PBR method is a viable alternative to a projection-based TAC.