Fish harvesting advice under climate change: A risk-equivalent empirical approach

relation to CC (expressed as E) if the management goal is to achieve the stock objective with the same level of risk. It can also inform managers on the relative change in risk associated with alternative management options under different climate scenarios, fostering transparency into decisions made considering CC-contributed uncertainty. This approach can therefore use previously observed stock productivity dynamics to define a safe operating space for fisheries given the projected future climate, the management objective and timeframe and the risk level considered acceptable. The approach can be used to expand stock exploitation advice to take CC into account, inform managers of the change in risk that can be anticipated under different climate scenarios, and support a transparent dialogue among scientists, managers, and stake- holders on how risk decisions can be altered by CC, by giving a rough magnitude of the changes potentially required in stock exploitation advice if CC is to be considered. Although this risk-based approach was designed to develop advice that considers CC, it can be applied to any ecosystem or environmental driver affecting stock production, for example in cases of habitat loss not caused by CC, or where there is potential for a degree of interdepen- dence between sustainable exploitation rates for a predator and a prey species. The main con- dition to applying this risk-based approach to other potential drivers is the need for a plausible hypothesis on how the external variable affects a stock’s production. At an even higher level

than fish stock production, the risk equivalent principles for altering advice are more universal and can work in any area of natural resource management where status quo advice is consid- ered possibly suspect because of a change in an external factor. Supporting information S1 Appendix. (PDF) S2 Appendix. (HTML) Acknowledgments Johanne Gauthier, Peter Galbraith and Denis Gilbert for providing the stock, temperature and oxygen data, respectively. Important feedback on many of the ideas presented here was pro- vided by participants of the DFO peer review meeting in incorporating CC into stock assess- ment advice in May 2018. Mariano Koen-Alonso suggested that density dependent processes should be explored. Author Contributions Conceptualization: Daniel E. Duplisea, Marie-Julie Roux, Karen L. Hunter, Jake Rice. Data curation: Daniel E. Duplisea. Formal analysis: Daniel E. Duplisea, Marie-Julie Roux, Jake Rice. Investigation: Daniel E. Duplisea. Methodology: Daniel E. Duplisea, Marie-Julie Roux, Karen L. Hunter, Jake Rice. Software: Daniel E. Duplisea. Validation: Marie-Julie Roux. Visualization: Daniel E. Duplisea. Writing – original draft: Daniel E. Duplisea, Marie-Julie Roux, Karen L. Hunter, Jake Rice. PLOS ONE Climate-change conditioned risk-equivalent fisheries advice PLOS ONE | https://doi.org/10.1371/journal.pone.0239503 February 19, 2021 20 / 22