DENVER – A 20-year government effort to restore the population of an endangered native trout in Colorado has made little progress because biologists have been stocking some of the waterways with the wrong fish, a new study says.
Advances in genetic testing helped biologists discover the error, which was called a potential black eye, but they said there is still hope for restoring the greenback cutthroat trout.
The three-year study, led by University of Colorado researchers and published online in Molecular Ecology on Aug. 28, said that five of the nine populations believed to be descendants of the endangered trout were actually the more common Colorado River cutthroat trout, which look similar.
The study said the results imply that the effort has "failed to improve the species' status."
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Lead author, Jessica Metcalf, who recently completed her doctorate in ecology and evolutionary biology at the university, was optimistic about the ongoing restoration program because four populations have been identified as "pure greenback cutthroat trout."
Bruce Rosenlund of the U.S. Fish and Wildlife Service, which is leading the recovery effort, said the agency is reviewing the study.
"The report is just a continuation of different expert input provided to the team for consideration for restoration," Rosenlund said.
Colorado and federal biologists have a goal of 20 self-sustaining populations of at least 500 fish each. The cost of the program was not available.
Greenback cutthroat trout were historically found in the drainages of the Arkansas and South Platte rivers in Colorado and a small part of Wyoming. They were declared extinct in 1937 because of overfishing, pollution from mines and competition from nonnative fish.
Researchers said remnant populations were found in the 1950s in tributaries and provided brood stock for fish raised in federal and state hatcheries and released in their native habitat.
The fish was added to the federal endangered species list in 1978.
The greenback were believed to be in 142 miles of waterways, including in Rocky Mountain National Park, Rosenlund said.
The new study, based DNA test results, found the greenback cutthroat trout's range is only 11 miles of streams.
The research results are a setback but state biologists believe the program will succeed over the long term, said Tyler Baskfield, Colorado Division of Wildlife spokesman.
"We've been moving fish around in the state since the late 1800s, and now the new science comes in and all of a sudden it's a different playing field," Baskfield said.
University of Colorado professor Andrew Martin, the study's principal investigator, said that while the findings might give the recovery program a "black eye," the hope is that biologists and agencies will move ahead on recovering the species before it goes extinct.