With global warming, stream temperatures will continue to rise, spelling disaster for many native trout. But federal research shows some populations could survive if their public-land habitat is preserved.

In an effort to preserve cold-water species, the U.S. Forest Service Rocky Mountain Research Station has developed Climate Shield, a project that uses stream, climate and geographical data to predict where species might find refuge against a warming climate.

The researchers argue that in a time of limited resources, money and effort should be spent on preserving habitat that is most likely to help species endure the challenges ahead.

To identify those areas, RMRS scientists analyzed more than 161,000 miles of streams in the Northwest where bull and cutthroat trout are most likely to survive. The Bozeman area is included on the eastern edge of the area.

Their findings were published this week in the scientific journal Global Change Biology.

They’ve also uploaded their data and mapping information to a website available to all, in the hopes that agencies and organizations will use it to make decisions.

The researchers found that the data from federal agencies such as the U.S. Fish and Wildlife Service were limited, so they reached out to state, local, educational and nonprofit entities in Montana, Washington, Oregon, Idaho and Wyoming.

The good news is that trout could persist in certain headwaters, the vast majority of which are on public land.

Because migrating bull trout need five times the territory, cutthroat trout will fare better.

Of the 33,000 miles of stream that are currently cold enough to host native trout, 80 percent of them flow through federal land while 10 percent travel through private property.

Less than 15 percent of native trout habitat is within protected watersheds.

By 2040, climate models predict that warming waters could cost native trout more than a third to a half of their habitat. Most of the losses would be in southern areas and at lower elevation, where most private land exists.

“Conserving native trout in the Rocky Mountains will largely be a public enterprise because the great majority of future habitats likely to be occupied occur on municipal, state, tribal and federal lands,” the authors wrote.

Cutthroat and bull trout need cold, clean water to survive, while nonnative species such as rainbow and brook trout can tolerate warmer water. Nonnatives are an added threat as they move into the cold-water refuges and are able to dominate native fish.

The scientists conclude that cutthroat trout may find new streams to inhabit as waters warm, so the threat to their survival comes mostly from competition with nonnatives. They suggest that wildlife agencies take action, such as removing nonnatives or erecting barriers to prevent their invasion of headwaters.

Montana Fish, Wildlife & Parks is already trying to do just that with eradication projects in the Shields River valley. Biologists are also installing barriers in the upper reaches to keep brook trout from reaching areas inhabited by Yellowstone cutthroat trout.

The RMRS highlights those same headwaters among others as future cold-water refuges, so FWP is ahead of the game there.

Pat Byorth of Montana Trout Unlimited, who has contributed to the Shields River project, said FWP has sought to preserve many pristine stretches tagged as refugia by the RMRS team.

“Biologists have been thinking in these terms for a long time. They’re just fundamental principles of good conservation that now dovetail into work on climate change,” Byorth said.

To learn more about the Cold Water Climate Shield effort, go to http://bdcne.ws/climateshield.

Contact Laura Lundquist at llundquist@dailychronicle.com or 582-2638. Follow on Twitter at llundquist.

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