The Wyoming Range, Cokeville - The shiny flash in the deep hole was simply too big to be a fish. Or was it?

The answer came when Warren Colyer's fly rod bent more than it should have as a 23-inch Bonneville cutthroat trout mistook the streamer on the end of the line for food.

Big fish are rare in streams like this one, some 35 miles off the paved road. But the chance of hooking large, post-spawn Bonneville cutthroat in their native range is growing thanks to federal and state wildlife agencies and nonprofit conservation groups like Trout Unlimited (TU).

Their efforts were sparked by the 1974 discovery of a genetically pure Bonneville cutthroat - previously thought extinct - by biologist Don Duff in the Deep Creek Mountains in western Utah. And their work has prevented the endemic cutthroat from being listed as threatened on the Endangered Species List.

The fish's name comes from the 20,000-square-mile ancient Lake Bonneville, which covered a large part of the Great Basin in Utah and small parts of eastern Nevada and southern Idaho.

It's appropriate that Colyer should land a big Bonneville cutthroat in its historic habitat. As head of TU's Bear River Native Trout program, Colyer has worked to remove barriers created by irrigation users in Idaho, Wyoming and Utah - which along with a small portion of Nevada, serve as the native range of the Bonneville.

As an aquatic ecology graduate student at Utah State University in 2000, Colyer placed radio telemetry tags on 55 Bonneville cutthroat on the Thomas Fork River a mile from its confluence with the Bear River to see if an irrigation diversion near the Idaho/Wyoming border was affecting the trout's spawning movement.

Initial reports showed the fish established a home winter range of about three miles. Come spring, they were on the move. He was able to track five into Wyoming. Two ended up in the Thomas Fork and the others disappeared. From an airplane, he found five in the Smiths Fork River, another tributary to the Bear, and some that had traveled at least 65 river miles seeking suitable spawning habitat in high mountain streams.

"People don't think about cutthroat trout like that. These fish are behaving like salmon; the Bear River is their ocean," Colyer said. "They spend the winter in big habitat and then spawn in small creeks, if they can find them."

Colyer was hired by TU and began to work on eliminating or modifying irrigation diversions in historic Bonneville cutthroat range in the Bear River drainage as part of TU's Protect, Reconnect, Restore, Sustain strategy for native fish populations.

Important discovery

Duff, then working as a fisheries biologist for the Bureau of Land Management and spurred by the recent introduction of the Endangered Species Act, had been looking for pure strain Bonneville cutthroat in Utah's West Desert since 1974.

A cutthroat search party had already been to the area, but Duff didn't think they had looked hard enough. His efforts were rewarded when DNA research proved he had found a genetically pure population.

He also found a population of Lahontan cutthroat, which are not native to Utah.

That prompted Utah's wildlife management agency to look at not only identifying and protecting pure cutthroat populations, but restoring them.

In 1978, there were only six known populations of Bonneville cutthroat in Utah and the fish were found in fewer than five miles of stream.

That's a far cry from the days when the fish were so abundant they were a reliable food source for American Indians and Mormon pioneers.

But efforts to restore native cutthroat populations have paid off. As of March, there were 165 conservation populations in Utah in more than 2,000 miles of streams, state fisheries officials say.

The Bonneville Cutthroat Trout Range-wide Conservation Team - led by Roger Wilson, cold water fish coordinator for the Utah Division of Wildlife Resources - reported this spring that Bonneville were back in roughly 2,498 miles of stream in the West. That's 38 percent of their historic range.

And there could be more.

Bear Lake, on the Utah/Idaho border, holds the largest lake population of Bonnevilles in their native range.

Annual spawning runs in tributaries provide somewhere between 10 to 15 percent of the cutthroat population in Bear Lake. Colyer and Idaho Fish and Game officials have been working on re-establishing spawning runs in lake tributaries by removing barriers and increasing water flows. State wildlife officials are working on similar projects on the Utah side.

Utah biologists also collect eggs and milt from Bonnevilles caught in a fish trap on Spawn Creek. More than 170,000 cutthroat have been raised from those eggs the past few years, but Utah officials want to bump up the total to 220,000 and have asked Idaho to contribute another 50,000.

Few anglers target cutthroat specifically at Bear Lake, but DWR fisheries biologist Scott Tolentino reports that the average Bonneville is longer than 19 inches, with several over 10 pounds caught every year. That's not impressive compared to reports of Bonneville cutthroat up to 40 pounds when pioneers were commercially netting the fish in Utah Lake, where they no longer exist.

Duff, now retired but still a member of the Bonneville Cutthroat Conservation Team, applauds state agencies for their efforts, but he and Colyer warn that serious threats are posed by energy development in Idaho, Wyoming and Utah and the potential loss of water in the West Desert to the Southern Nevada Water Authority Groundwater Pumping Project.

"The agencies could get complacent now that they have reached many of their goals for the Bonneville cutthroat," Duff said. "They need to provide constant monitoring and balance the use of the land for protection of the water and its resources."

Brett Prettyman can be contacted at brettp@sltrib.com or 801-257-8902.