Potential implications of climate change on the Patagonian toothfish fisheries management

Climate change can impact fish stocks through different processes with two main impacts for a given stock: the migration of the stock and the decrease of its biomass. In the case of Patagonian toothfish, it seems unlikely that migration will occur due to the bathymetric constraints in its life cycle, but there is already an observed decrease in the reproductive biomass in all managed Patagonian toothfish stocks. This decrease in biomass has mostly been associated with low recruitment years. However, the causes of this decline in our knowledge have not been clearly identified (natural variability, long term changes, consequence of the harvest strategy ?). Whether the current decline is a result of environmental change or not, climate change could contribute to it and challenge many of the conventional assumptions that scientists rely on to assess stock status and estimate total allowable catch (TAC). In particular, the current fishery management is mostly based on a static view of the stock’s characteristics and may not be adapted to a stock with changing properties over time if long term sustainability is seeked for. Tools already exist that could contribute to a climate-adaptive management (the precautionary principle, ecosystem-based management). A work on the implications of climate change for the Patagonian toothfish management in the Southern Indian Ocean is underway in our group. Preliminary results suggest three potential lines of discussion: i) adapting the current methodology, ii) developing a stronger risk management approach and iii) enhancing stocks resilience.