Climate Change Impacts on Fisheries and Aquaculture Are Less Well Understood

The impacts of climate change on seafood are far less well known than impacts on agriculture. Year-to-year climate variations cause large fluctuations in fish stocks, both directly and indirectly, and this has always posed a challenge for effective fisheries management. Similar sensitivities to longer time-scale variations in climate have been documented in a wide range of fish species around the globe. Shifts in fisheries distributions are expected to be most pronounced for U.S. fisheries in the North Pacific and North Atlantic, since future temperature increases are projected to be greatest at these higher latitudes and warming will be coupled to major habitat changes driven by reduced sea ice. The effects of ocean acidification (described above) may be even more important for fisheries than the effects of rising temperatures, although they are currently even more uncertain. Many fished species, including invertebrates like oysters, clams, and scallops, produce shells as adults or as larvae, and shell production could be compromised by increased acidification. Other species fished by humans rely on shelled plankton as their primary food source, and projected declines in these plankton species could have major impacts on fished species higher in the food chain. Finally, acidification can disrupt a variety of physiological processes beyond the production of shells.

Freshwater fisheries face climate challenges similar to those of marine fisheries. Complex interactions among multiple factors such as elevated temperature, reduced dissolved oxygen, increased stratification of lakes, and elevated aquatic pollutant toxicity at higher temperatures pose particular challenges to freshwater fisheries and make projections uncertain. Indirect effects such as altered streamwater flows, changing lake levels, and extreme weather events, coupled with the inability of freshwater fish to move between watersheds, will affect freshwater fisheries, but detailed projections are highly uncertain. Cold-water species such as trout and salmon appear particularly sensitive.

Aquaculture is growing rapidly in the United States and elsewhere as the availability of wild seafood declines. Impacts of climate change on aquaculture are not well studied, but ocean acidification and the difficulty of moving aquaculture infrastructure to new locations as fish habitats shift may pose significant challenges to aquaculture production.

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