Monday, 19 October 2015

Feds eye refuges for cold-water species in 5 states

By KEITH RIDLER | Associated Press – 19 minutes ago

BOISE, Idaho (AP) — Federal scientists using new technologies have mapped what is being called a Cold Water Climate Shield, an area spanning five western states that could support viable populations of native species if the region continues its warming trend.

Mapping the cold-water refuges for cutthroat trout, a favored sport fish among anglers, and threatened bull trout could help resource managers make decisions aimed at preserving populations of those and other cold-water native species in Idaho, Oregon, Washington, Montana and Wyoming.

Scientists say streams in the region have warmed up about a degree over the last three decades and are getting hotter.

"One of the things we're seeing is that the colder areas are typically in the headwaters," said Dan Isaak, a research fisheries biologist with the U.S. Forest Service in Boise. "Those are warming up a lot more slowly than streams at lower elevations."

The mapped area contains streams with temperatures preferred by cutthroat trout and bull trout but are too cold for non-native species, particularly brown trout and brook trout, thus forming the climate shield. The climate shield has practical applications, Isaak said.

"Rather than spending money to build artificial barriers on streams to prevent the upstream advance of invasive species (which is very expensive and commonly done in some areas), the climate refugia streams we're highlighting are so cold that you wouldn't need to build a barrier to preserve the native community," Isaak said in an email to The Associated Press.

Within this climate shield, scientists say some areas will remain capable of supporting bull trout even if the more extreme future climate models turn out accurate.

"It's quite possible much of the habitat for bull trout will become too warm," and it will disappear from those areas, said Mike Young, a research fisheries biologist for the U.S. Forest Service based in Missoula, Montana, also working on the climate shield. "But we think that even under extreme climate scenarios bull trout will persist in the lower 48."

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