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A Talk on the Wild Side.

Tennessee: Joint Venture Strives to Determine the Effects of Climate Change on Brook Trout

An adult trout lying on a rock
Adult Brook Trout. These fish, known for their distinct coloring, face fragmented populations, habitat loss, invasive species, degraded streams, longer droughts, more intense wet periods, and temperature changes. Photo: USFWS. Download.

In his book, Shin Deep, Chris Hunt writes about why many fly fishermen pursue brook trout.  

“Its deep colors seem to provide a beacon of light in the near darkness of the evening, almost like a neon beer sign in a dank, dark, but wonderfully familiar tavern.” 

“You can’t help but stare at it.”

This hypnotic appeal draws fly fishermen like Robert Ramsay to the Great Smoky Mountains National Park to chase brook trout holed up in cold mountain streams, like the West Prong of the Little Pigeon River that runs along the park’s Chimney Tops trail. “It’s like going back in time when you chase these brook trout in remote, higher elevation streams,” says Ramsay, who works for the Georgia Conservancy and has fly-fished on four continents. “I have a hard time thinking about the Smoky Mountains without brook trout in their streams.

Preventing this scenario is precisely why a growing number of partners are collaborating through the Eastern Brook Trout Joint Venture to determine how accelerating climate change and other challenges will impact Southern Appalachian brook trout populations in Tennessee and other states, and what biologists can do to protect the iconic fish.

In collaboration with many conservation organizations, the U.S. Fish and Wildlife Service developed and released an ambitious strategy for responding to accelerating climate change and addressing its impact on critters like brook trout. The Service and joint venture are working on a climate change monitoring program, targeting 400 sites aimed at taking a closer look at how air and water temperatures impact brook trout.

Trout swimming in a school

These brook trout were photographed in their native habitat: a fast-moving, coldwater stream. The single most important factor affecting brook trout is water temperature, which is why biologists are concerned about this species as climate change accelerates. Brook trout thrive in water temperatures of 65 degrees Fahrenheit or less. They will die after only a few hours in water temperatures of 75 degrees Fahrenheit. Photo: USFWS. Download.

Fragmented populations, habitat loss, invasive species, degraded streams, longer droughts, more intense wet periods, and temperature changes have some of the best coldwater fisheries biologists joining forces to ensure these trout survive for the next generation of anglers.   

“We are not trying to prove what causes climate change one way or another,” says Mark Hudy, a coldwater fisheries biologist for the U.S. Forest Service based at James Madison University. “We are trying to determine what management actions we can take to make the trout more resilient to the changes we are seeing. Bottom line is that the current distribution of brook trout will change.”

Climate change’s unpredictability poses unique challenges. How to address changes in precipitation remains a concern, according to Doug Besler, a coldwater fisheries biologist for the North Carolina Wildlife Resources Commission.

“We might get the same amount of precipitation annually, but what if it comes in bunches at times of the year that aren’t considered normal?  That’s one of the many things we worry about because it’s very hard to plan for that kind of unpredictability,” Besler says.

Other questions remain unanswered.

“Some of these changes are going to affect these fish and their habitat in ways we cannot imagine today,” says Steve Moore, lead fisheries biologist for the National Park Service in the Smokies.  “What if the normal stream temperature goes from 62 degrees to 65 or 66 degrees?  We don’t know the answer to that one."

There are about 100 brook trout populations in Tennessee streams.

Two men stand in water with nets

Biologists conduct a sampling survey for brook trout. The U.S. Fish and Wildlife Service and the Eastern Brook Trout Joint Venture are studying the impacts of climate change on brook trout. They are monitoring 400 sites to find out how changes in air and water temperatures affect the fish. Photo: USFWS. Download.

“A big problem now is that these brook trout populations in the Southern Appalachians are becoming more fragmented,” says Jim Habera, a coldwater specialist with the Tennessee Wildlife Resources Agency.  “This makes them easier to lose.”

The introduction of rainbow and brown trout into streams in the Southern Appalachians contributes to the problem by pushing brook trout into smaller pockets of water, shrinking access to available habitat.

Though brook trout have suffered significant habitat loss, biologists are working to reunite fragmented populations. Moore and joint venture partners are attempting to return an eight-mile stretch of the Lynn Camp Prong to brook trout by removing rainbow trout.

“The Southeastern Appalachian brook trout is nature's poster child in the Southeast,” Moore says. "If we can do good for them in the face of change, then we will be able to do more good for (natural) coldwater fisheries across the region."

 For Ramsay, the rewards for this work will mean being able to chase brook trout with his son in the Chimney Tops for decades to come—just as he does with his own father today.


Climate Change Focus: Adaptation, Engagement

Author: Jeff Fleming, USFWS, Southeast Region External Affairs Office, 404-679-7287, Jeffrey_M_Fleming@fws.gov


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