Public Release: 30-Jun-2016 In hot water: Climate change is affecting North American fish US Geological Survey

http://www.eurekalert.org/pub_releases/2016-06/ugs-ihw063016.php

Public Release: 30-Jun-2016
In hot water: Climate change is affecting North American fish
US Geological Survey

Climate change is already affecting inland fish across North America -- including some fish that are popular with anglers. Scientists are seeing a variety of changes in how inland fish reproduce, grow and where they can live, according to four new studies published today in a special issue of Fisheries magazine.

Fish that have the most documented risk include those living in arid environments and coldwater species such as sockeye salmon, lake trout, walleye, and prey fish that larger species depend on for food.

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.

These changes will have direct implications - some good, some bad - for recreational fishers, who, in the United States alone, contributed nearly $700 million in revenue to state agencies through license, tag, stamp, and permit purchases in 2015. Annually, anglers spend about $25 billion on trips, gear, and equipment related to recreational fishing in U.S. freshwaters.

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Other major findings:

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.

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