Available trout habitat may decline with climate change

A new study shows climate change could cut suitable trout habitat in the western U.S. in half over the next 70 years, with some species of trout experiencing greater decline than others, researchers announced Monday.

The results were reported by a team of 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.

The study, published in the peer-reviewed science journal Proceedings of the National Academy of Sciences, predicts native cutthroat throughout the West could decline by as much as 58 percent, while introduced brook trout could decline by as much as 77 percent. Rainbow and brown trout populations would also decline by an estimated 35 percent and 48 percent respectively.

"The study advances our understanding of climate change impacts by looking beyond temperature increases to the role of flooding and interactions between species," said Trout Unlimited's Dr. Seth Wenger, the paper's lead author, in a statement. "The study also is notable in scope, using data from nearly 10,000 sites throughout the western United States."

Wenger was quick to point out that, while the predictions are indeed dire, there is hope. By restoring and reconnecting coldwater drainages and by protecting existing healthy habitat largely located on public lands in the West, some of the decline in trout populations can likely be avoided.

"This report is a wake-up call," said Chris Wood, the president and CEO of Trout Unlimited. "The good news is that we're already working to protect high-quality trout habitat, such as backcountry roadless areas on national forests. We're reconnecting tributaries to mainstem rivers, and we're restoring degraded habitat. It is imperative that we accelerate the scope and the pace of that work if we are to have healthy trout populations and the irreplaceable fishing opportunities they provide through this century."

Wenger and his fellow researchers used an "ensemble" of climate models to arrive at the study's findings. Some models predicted more warming than others, but under even the most "optimistic" model, cutthroat trout populations in the West could decline by 33 percent. Scientists note that cutthroat trout populations are already in trouble - some subspecies have been removed from 90 percent of their historic native range and are listed under the Endangered Species Act. Declines from a changing climate would impact native cutthroat trout beyond the impacts they've already suffered