Findings on wrong-trout recovery forces biologists to regroup

DENVER — State and federal biologists, still smarting from research showing that they may have been protecting the wrong fish the past 20 years, are regrouping in their efforts to restore the rare greenback cutthroat trout to Colorado waters.

State biologist Tom Nesler had hoped to see the fish removed from the endangered species list during his career. He concedes that might not happen if it turns out some of the greenback populations biologists thought they were saving are actually the similar but more common Colorado River cutthroat trout.

A three-year study led by University of Colorado researchers, published in August, found that out of nine fish populations believed to be descendants of original greenbacks, five were actually Colorado River cutthroat trout.

The recovery effort was thought to be near its goal of establishing 20 self-sustaining greenback populations.

"Hey, science happens," said Nesler with a shrug as he discussed the findings.

Not that Nesler, chairman of the greenback recovery team, takes the study lightly. He and other members of the team — which includes four federal agencies, agencies from three states, an Indian tribe and a conservation group — are doing further testing and review.

Greenback cutthroat trout were historically found in the drainages of the Arkansas and South Platte rivers in Colorado, east of the Continental Divide, and a small part of Wyoming. The Colorado River cutthroat trout is native to the upper Colorado River basin, west of the divide.

Greenbacks were declared extinct in 1937 due to overfishing, pollution from mines and competition from nonnative fish. But researchers said remnant populations were found in tributaries in the 1950s. The fish was added to the federal endangered species list in 1978.

Under the state-federal recovery program, biologists used fish they believed to be descendants of pure greenback cutthroat trout as brood stock. New fish, raised in hatcheries, were released in different waters, Nesler said, not where the remnant populations were.

As team members huddle to chart the course forward, they're also trying to explain why what they thought were greenbacks weren't. In a letter to the state natural resources chief, four Colorado legislators denounced "this significant scientific blunder" as a waste of taxpayer dollars.

The Colorado Division of Wildlife has spent an average of $320,000 annually for the past five years to restore the greenback. Most of the money has come from state lottery revenue; no state tax dollars have been used.