Effects of Climate Change on North American Fish

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Four new USGS supported studies published in a special issue of Fisheries magazine offer insights into how climate change is affecting inland fish across North America.

Research indicates that fish living in arid environments and coldwater species such as sockeye salmon, lake trout, walleye, and prey fish that larger species depend on for food are at risk from the effects of climate change.

Climate change can cause suboptimal habitat for some fish; warmer water, for example, can stress coldwater fish. When stressed, fish tend to eat less and grow less.

For other fish, climate change is creating more suitable habitat; smallmouth bass populations, for example, are expanding.

“The U.S. Geological Survey and partners are working to provide a fuller and more comprehensive picture of climate change impacts on North American fish for managers, scientists, and the public alike,” said Abigail Lynch, a lead author and fisheries biologist with the USGS National Climate Change and Wildlife Science Center.

The authors reviewed 31 studies across North America that document fish responses to climate change. The manuscripts describe the impacts of climate change to individual fish, populations, recreational fishers, and fisheries managers.

“Thanks to this synthesis, we can see the effects of climate change on inland fish are no longer just future speculation, but today’s facts, with real economic, social, and ecological impacts,” said Doug Austen, Executive Director of the American Fisheries Society and publisher of Fisheries magazine.

The authors emphasize that resource managers can take many actions to help sustain resilient fish communities and fisheries.

Effects of Fish

Climate change may be altering abundance and growth of some North American inland fishes, particularly coldwater fish such as sockeye salmon, a species experiencing well-documented shifts in range, abundance, migration, growth, and reproduction.

Climate change may be causing earlier migration timing and allowing species that never occurred together previously to hybridize. For example, native westslope cutthroat trout in the Rocky Mountains are now hybridizing with rainbow trout, a non-native species.

Shifts in species’ ranges are already changing the kinds of fish in a specific water body, resulting in new species interactions and altered predator-prey dynamics. For example, in Canada, smallmouth bass have expanded their range, altering existing food chains because the species compete against other top predators for habitat and prey fish.

Droughts are forecasted to increase in frequency and severity in many parts of North America, especially in arid rivers. Such droughts exacerbate the impacts of water flow regulation in ways that affect people, fish, and aquatic systems.

The following papers are available in Fisheries magazine, published by the American Fisheries Society:

Physiological basis of climate change impacts on North American inland fishes, authored by James E. Whitney (Pittsburg State University), Robert Al-Chokhachy (USGS), Bo Bunnell (USGS) and others.

Climate change effects on North American inland fish populations and assemblages, authored by Abigail J. Lynch (USGS), Bonnie J. E. Myers (USGS), Cindy Chu (Ontario Ministry of Natural Resources and Forestry; OMNRF) and others.

Identifying alternate pathways for climate change to impact inland recreational fishers, authored by Len M. Hunt (OMNRF), Eli P. Fenichel (Yale University), David C. Fulton (USGS) and others.

Adapting inland fisheries management to a changing climate, authored by Craig P. Paukert (USGS), Bob A. Glazer (Florida Fish and Wildlife Conservation Commission), Gretchen J. A. Hansen (Minnesota Department of Natural Resources) and others.

The research was supported by the USGS NCCWSC, which collaborates with universities, resource management organizations, tribes and other partners to provide unbiased scientific data and tools that contribute to an understanding of the widespread impacts of climate change on fish, wildlife, ecosystems, and people.

source: U.S. Geological Survey