Report: Freshwater Fish Affected By Climate Change

Sep 6, 2013

A new report by the National Wildlife Federation finds freshwater fish are already beginning to feel the impact of climate change.

The report is titled “Swimming Upstream: Freshwater Fish In A Warming World.” It finds several troubles for cold water fish, such as loss of habitat and encroachment of warm water species. The report also finds that climate change exacerbates already existing problems, like habitat loss, pollution, invasive species and disease.

National Wildlife Federation senior scientist Dr. Doug Inkley is the study’s lead author, and he finds some lakes, rivers and streams are already increasing in temperature.

“As a result, some of the composition of the species and the habitats are actually being compromised,” Inkley said.

One example is forest fires in the west. They cause excessive sediment runoff. That runoff turned Colorado’s Poudre River black. Inkley blames climate change for those forest fires.

“That’s not good for cold water species like trout,” Inkley said.

Freshwater species need high quality habitat that must be clean and well-oxygenated, and it must provide spawning habitat.

“We have had a tremendous degradation of the waters of the United States because of the way that we’ve treated our waters. We use them as our sewers,” Inkley said.

Thirty-seven percent of freshwater species are considered at-risk.

Cold water fish like trout and salmon are suffering the most, Inkley said. He points to the brook trout, which is native to the Appalachian range.

“Already they are extirpated or gone from more than 35 percent of their habitat in Virginia alone,” Inkley said. “These fish are being forced upstream into colder and colder waters because the lower stream waters are too warm.”

But cold water fish are not alone. Warm water species like bass also feel the impact.

“When the water gets too warm even for warm-water species, disease can set in [and] invasive species can be a bigger problem,” Inkley said. “So it’s not necessarily all good for warm-water species. There will be challenges of climate change for them as well.”

The drought that baked much of the Midwest last year had profound impact on freshwater fish. It dropped water levels and significantly increased water temperatures.

“There was significant die offs of fish in many areas where they normally don’t occur. With climate change, we expect this to increase,” Inkley said.

The report finds recreational fishing was a $25.7 billion dollar industry in 2011, and 27 million adults went fishing that year. In Missouri, over one million people fished in 2011 and spent over $618 million.

Inkley said the loss of healthy fish populations will have a negative economic impact on rural communities that rely on that recreation fishing.