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Cutthroat trout lineage thought to be extinct discovered in remote streams of southwest Colorado

Posted at 1:24 PM, Sep 05, 2018
and last updated 2018-09-05 15:24:33-04

DURANGO, Colo. – Colorado Parks and Wildlife announced Tuesday that its biologists had discovered groups of cutthroat trout living in southwest Colorado that were thought to be extinct.

CPW said new and more-advanced genetic testing methods led to the discovery that the Colorado River trout collected by biologists shared genetics with the population that was thought to be gone.

Eight populations of the trout were found in streams within the San Juan National Forest and on private property within the San Juan River Basin, and had been reproducing naturally in isolated areas, CPW said.

Three current and former CPW aquatic biologists and cutthroat specialists who have been looking for remote trout population in southwest Colorado for decades have been taking samples to preserve for when genetic testing advances were made, which CPW says has happened over the past 10 years.

The recent discovery that the fish thought to be extinct were still alive also happened because a naturalist preserved two cutthroats collected from the San Juan River near Pagosa Springs in 1874. (See photos above.)

The fish had been housed at the Smithsonian National Museum of Natural History in Washington, D.C. for decades and were rediscovered in 2012 by a team from the University of Colorado that was studying old trout samples housed in museums across the country.

The research team genetically tested the two old trout and found they had genetic “fingerprints” that are unique to the San Juan Basin, then cross-tested all the cutthroat species they could find there.

“These fish were discovered because of our curiosity and our concerns for native species,” said John Alves, the senior aquatic biologist for CPW’s Southwest Region. “We’re driven by scientific inquiry that’s based on hard work and diligence. This is a major discovery for Colorado and it shows the critical importance of continuing our research and conservation work.”

There are 14 different subspecies of cutthroat trout in North America, and at least three are found in Colorado: the Colorado River cutthroat trout, the Greenback cutthroat trout and the Rio Grande cutthroat trout.

CPW says it will be developing a brood stock of the rediscovered species to reintroduce it into the headwaters of the San Juan River and a conservation plan to protect the fish “over the next few years.”

“We always ask ourselves, ‘What if we could go back to the days before pioneer settlement and wide-spread non-native fish stocking to see what we had here?’” said Jim White, a CPW aquatic biologist who has worked on the project. “Careful work over the years by biologists, finding those old specimens in the museum and the genetic testing gave us the chance, essentially, to go back in time. Now we have the opportunity to conserve this native trout in southwest Colorado.”