Study reveals trout habitats could suffer from changes in global climate

Small streams harboring remnant populations of cutthroat trout, including Trapper Creek on the Roan Plateau (above), are particularly susceptible to global climate change. A new study predicts cutthroat populations may decline by 50 percent in the next 70 years.

Changes in global climate could slash trout habitat in the Western U.S. by 50 percent over the next 70 years, says a new report from Trout Unlimited.

The report, to be published Monday in the peer-reviewed science journal Proceedings of the National Academy of Sciences, warns native cutthroat throughout the West could decline by as much as 58 percent and the non-native brook trout could decline by as much as 77 percent.

Rainbow and brown trout populations, according to the study, also would decline, by an estimated 35 percent and 48 percent, respectively.

The study was the result of work accomplished by 11 scientists from Trout Unlimited, the U.S. Forest Service Rocky Mountain Research Station, Colorado State University, the U.S. Geological Survey and the University of Washington Climate Impacts Group.

According to the report, the decline of cutthroat trout is “of particular significance” because cutthroats are the only trout native to much of the West.

They also are considered a “keystone species” in the Rocky Mountain ecosystem, says the report.

According to Colorado Parks and Wildlife, cutthroat trout are the most diverse trout species in North America.

“The study advances our understanding of climate change impacts by looking beyond temperature increases to the role of flooding and interactions between species,” said Seth Wenger, a Boise, Idaho-based scientist for Trout Unlimited and the report’s lead author.

“The study also is notable in scope, using data from nearly 10,000 sites throughout the western United States,” Wenger said.

The dire news, however, is balanced by some hope, Wenger noted.

By restoring and reconnecting coldwater drainages and by protecting existing healthy habitat largely located on public lands in the West, he said some of the decline in trout populations can likely be avoided.

“Essentially, Trout Unlimited is already protecting remaining strongholds and restoring degraded habitat — exactly the kind of things that need to be done to reduce the impact of a changing climate on coldwater fisheries in the West,” Wenger said.

The involved scientists used a mix of climate models in their studies, and although some predicted more warming than others, even the most optimistic predicted cutthroat trout populations would decline by one-third across the West.

Several cutthroat trout species already are in decline, with some subspecies having lost 90 percent of their historic native range, the report says.

“This study reinforces the danger in congressional proposals that would remove protection from backcountry roadless areas and cut funding for state and federal natural resource agencies,” said Chris Wood, Trout Unlimited president and CEO.

The study can be read online Monday at the Trout Unlimited home page,, or at the Proceedings of the National Academy of Sciences website,

Anglers retire, to spend golden years hassling trout: Well-known Grand Valley anglers Pat and Carol Oglesby, both long-time and ardent supporters of Trout Unlimited and Federation of Fly Fishers, retired Friday, which means there isn’t a trout, or any fish that rises to a fly, that’s safe.

The Oglesbys spent countless hours working on behalf of coldwater fisheries across Colorado and the West, and their efforts fostering the Western Colorado Fly Fishing Exposition won’t be easy to follow.

They leave the expo and the local Trout Unlimited chapter in great and competent hands, but many of us, anglers or not, will long be grateful for their friendship, mentoring and always-helpful attitude.


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