Climate change impacts on the biophysics and economics of world fisheries

449 Gross revenues from marine capture fisheries worldwide are estimated at between US$80 billion and 85 billion annually1–3. As a primary industry4, fisheries support the wellbeing of nations through direct employment in fishing, processing and ancillary services amounting to between US$220 billion and 235 billion annually in 2003 (ref. 5). Globally, fish provide nearly three billion people with 15% of their animal protein needs1, and not only to people who reside in the 144 maritime countries of the world, as international fish trade has made fisheries truly global6. When post-harvest activities and workers’ dependants are considered, the number of people directly or indirectly supported by marine fisheries is about 520 million, or nearly 8% of the world’s population1. In most lowand middle-income maritime countries, fisheries employment is crucial as it provides some of the world’s poorest with a cash income and nutrition, especially during times of economic hardship7. Global marine fisheries are underperforming, mainly because of overfishing, but also because of pollution and other anthropogenic causes8–10. Climate change will complicate the challenges currently facing global fisheries, as it has begun to alter ocean conditions, particularly water temperature and biogeochemistry. These changes are expected to affect the productivity of marine fisheries11,12. Preliminary results from recent studies estimate that climate change will lead to losses in revenues, earnings to fishing companies and household incomes in many regions, although some countries and/ or regions may realize increases in fisheries benefits13–17. The close links between the biophysical components of marine ecosystems and the socio-economics of fisheries mean that integrated assessments across disciplines are needed to understand climate change impacts on human welfare through marine fisheries. Effects of global ocean–atmosphere changes act at multiple levels of organization of marine ecosystems and human society, including individual organisms, populations of organisms, communities and ecosystems, the economics of fisheries and larger global issues, such as global food security, energy supply and food prices (Fig. 1). Here, we review existing knowledge on the responses of marine ecosystems to ocean and climate changes, and how these changes are expected to affect the economics of global marine fisheries, and describe approaches that can be used to adapt to these changes. We focus on climate change (long-term changes in mean conditions), Climate change impacts on the biophysics and economics of world fisheries