Evaluating the impact of multi-year research catch limits on overfished toothfish populations
In stocks that have been depleted by overfishing, the benefit of additional fisheries removals for research purposes needs to be evaluated against the risk that such catches may contribute to delaying or preventing the recovery of such stocks. Through simulating a Patagonian toothfish (Dissostichus eleginoides) stock that has been subjected to varying levels of overfishing and research catches, this study shows that stocks can take decades to recover even in the absence of fishing, and relatively low levels of research catch can significantly delay the recovery of a stock. Scenarios assessed in this study indicate that, where a stock has been depleted to at or below 20% of the median unfished spawning stock biomass, research catches in excess of 0.6% of median unfished total stock biomass should be avoided to ensure that research does not significantly impact on the recovery of depleted stocks in the long term. Research catches may need to be even lower where there is uncertainty regarding the key parameters related to stock productivity, such as growth, maturity, recruitment or natural mortality rates.