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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]

Rebuilding fish populations worldwide is urgently needed, but socio-economic concerns often slow down or even prevent the process of rebuilding fish stocks. To address this concern we conduct an economic analysis of rebuilding six depleted Canadian fish stocks under different biological and management scenarios. Rebuilding scenario projections are based on underlying fish stock assessments and fish species' life history traits, and thus are also influenced by uncertainties in these parameters. We find that rebuilding generates economic gains for five of the six fish stocks in the long term, with estimated economic gains under the most and least optimistic scenarios reaching up to 11 times and 5 times above the status quo, respectively. In most cases, fishery closure generates higher potential economic gains compared to a low-fishing strategy, regardless of the rate of fish stock recovery. Intergenerational discounting increases estimated economic benefits, thereby emphasizing the importance of taking a long-term perspective to fisheries rebuilding. Our results suggest that bearing the short-term economic costs of rebuilding can lead to future economic benefits, which in the long term are an improvement over maintaining the status quo. • Fisheries rebuilding results in long term economic gains for 5 out of 6 stocks. • Most optimistic scenario estimated economic gain of 11 times above the status quo. • Rebuilding led to NPV losses for yelloweye rockfish, a long lived, choke species. • Fishery closure scenarios resulted in highest projected economic gains. • Bearing short-term economic costs of rebuilding can lead to future benefits. [ABSTRACT FROM AUTHOR]