Trade-offs in fishery management objectives when allowing catch limit carry-over between years

Abstract

Abstract Fisheries managed with explicit annual catch limits often have realized catches below the total allowable catch. Carry-over provisions allowing aggregate or individual carry-forward of catch underages are included in many fishery management systems, but the ramifications of these provisions on different fishery management objectives such as average catch, variability in catch, and probability and degree of overfishing are not well understood. We developed a management strategy evaluation simulation to explore performance of alternative carry-over policies assuming different life histories and under different causes of catch underages. We evaluated the impacts of the carry-overs across common management objectives to understand the trade-offs associated with different amounts of allowable carry-over. We find that carry-overs can increase yield to the fishery but can also increase the risks of overfishing, low stock biomass, low catch, and the interannual variability in catch. All of these risk measures increase with the amount of carry-over allowed in most cases, but for cases of low stock productivity or positively biased stock assessment estimates, larger carry-over allowances resulted in similar or lower yield compared to smaller allowances. The analysis suggests that some benefits of carry-over can be maintained and risks can be limited by restricting the maximum carry-over allowed.