Challenges to transboundary fisheries management in North America under climate change.

Climate change is shifting the distribution of fish stocks that straddle between exclusive economic zones (EEZ), challenging transboundary fisheries management. Here, we examine the projected sharing of jointly managed transboundary fish stocks between Canada and the United States. We hypothesize that ocean warming will alter the sharing of fish stocks between the two countries, and that such changes will intensify under a high carbon emission scenario. We look at the specific cases of the International Pacific Halibut Commission that manages Pacific halibut (Hippoglossus stenolepis) and a resource sharing arrangement in the Gulf of Maine for cod (Gadus morhua), haddock (Melanogrammus aeglefinus), and yellowtail flounder (Limanda ferruginea) to discuss the management consequences of shifts in transboundary stocks. We rely on multiple Earth system models' simulations and species distribution models to estimate the change in catch potential and stock share ratio of each transboundary stock in the 21st century under two climate change scenarios. Results show that, even under a low emission scenario, most transboundary fish stocks sharing ratios, i.e., the proportion of the total catch of a fish stock taken by a given country, will change by 2050 relative to present. The overall reduction in catch potential, in addition to the changes in stock-share will further exacerbate trade-offs between changes in species catch potential. Such trade-offs in the Atlantic and Pacific regions will be amplified if a high emission scenario is followed, relative to a low carbon emission scenario. Based on the simulation results, we examine possible solution options to reduce climate risks on transboundary fish stocks and fisheries. [ABSTRACT FROM AUTHOR]