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Chasing Brook Trout

As the climate changes, brook trout and anglers will be forced to move north to cooler streams.

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Scientists often resort to language that fails to convey the impact of warming when trying to explain the potential effects of climate change on plants, fish, and wildlife. Now, a study by Penn State’s College of Agricultural Sciences fisheries researchers clearly explains the impact of projected warming waters on wild brook trout in the eastern U.S. for fishermen.

The eastern brook trout occurs in small cold-water streams and lakes, and self-sustaining populations support angling throughout the Appalachian Mountains. However, warming air temperatures are expected to reduce available cold-water habitat and result in a smaller brook trout distribution and fewer angling opportunities.

Tyler Wagner, adjunct professor of fisheries ecology, and Tyrell DeWeber, now a postdoctoral scholar at Oregon State University, used two models they previously developed, one predicting stream temperature and one predicting where brook trout might occur, to identify streams likely to support wild brook trout under current and future climate scenarios.

The researchers then calculated the distance required to drive from 23 cities spread throughout the eastern brook trout range to the 10 nearest stream segments likely to have wild brook trout under current and future conditions.

“Climate change is expected to result in widespread changes in species distributions for freshwater fish species,” said Wagner, who is assistant unit leader of the Pennsylvania Cooperative Fish and Wildlife Research Unit at Penn State. “Although anglers and other resource users could be greatly affected by these predicted changes, changes are rarely reported in ways that can be easily understood by the general public.”

DeWeber, who was a doctoral student at Penn State when the research was conducted, noted that travel costs based on distance have been widely used to value ecosystem services, such as angling under climate-change scenarios, but have not been used for communicating potential changes to the public, despite the intrinsic link to everyday life.

“Under current conditions, brook trout are predicted to occur in streams throughout the region, and average driving distances from cities to the nearest streams are predicted to offer angling opportunities ranging from 4 to 87 miles,” said DeWeber. “As a result of projected warming, driving distance to go fishing for wild brook trout was predicted to increase, on average, by almost 164 miles over the next 70 to 80 years.”

The lengths of trips from many northern cities were predicted to remain relatively short in the future because nearby streams were still expected to support brook trout under warmer conditions, but anglers in southern cities would experience dramatic increases in the lengths of trips because brook trout are predicted to be lost in surrounding areas.

It is unlikely that many anglers would drive great distances to fish very often, especially if remaining streams become popular and crowded, DeWeber noted. He believes that losses of wild brook trout populations and increased trip lengths would likely result in reduced resource use in many areas. But he suggested that people are unlikely to be concerned about the potential effects of warming if they do not understand what may be coming.

—Emily Bartlett