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A stream flows into Herman Gulch, Monday, Sept. 26, 2022, in Clear Creek County. Colorado Parks and Wildlife confirmed that the greenback cutthroat trout reintroduction efforts had successfully reproduced fish on their own in Herman Gulch. (Hugh Carey, The Colorado Sun)

For decades, experts feared Colorado’s greenback cutthroat trout to be extinct, a casualty of mining pollution, anglers and more competitive species. So when biologists made the improbable discovery of a naturally reproducing population in a short stretch of Bear Creek west of Colorado Springs 10 years ago, they clung to the hope that the near-miracle could be replicated.

Last Friday, Colorado Parks and Wildlife confirmed that the Bear Creek greenbacks now have company. Reintroduction efforts in Herman Gulch, the popular hiking destination just off Interstate 70 near the Loveland ski area, have yielded fish that are reproducing on their own — and sparking renewed optimism that other greenback stocking projects will soon follow suit.

State natural resources officials said the news affirmed their “bedrock mission” to support wildlife across the state and reflected years of collaborative effort among agencies. The stocking in Herman Gulch started in 2016, and now includes its first population of greenback cutthroats — the official state fish — old enough to reproduce . 

“It’s kind of a waiting game for those fish to mature and reproduce,” said Josh Nehring, assistant aquatic section manager for CPW. “So we’re just super excited and hoping to get a lot more populations out on the landscape.

“In a typical system, when we’re trying to start a population, we will often stock three-year classes — so stock fry (young fish) for three years in a row,” Nehring added. “And typically in three years they become sexually mature. And so hopefully after three years of stocking or four, we should have adults in the population to where they can start reproducing on their own.”

Colorado Trout Unlimited lauded the announcement as great news for the state’s watersheds, and a reward to the nonprofit’s volunteers who lugged water tanks bearing greenback fry up Herman Gulch multiple years in a row. 

“For everybody who helped in some way getting fish into Herman Gulch, it’s a great first step toward that long-term conservation goal,” executive director David Nickum said. Wildlife advocates will be watching to see if reproduction is sustainable for such places in Colorado, he said. 

That greenback cutthroat trout have managed to reproduce in the Herman Gulch high country is the latest development in a complicated, decadelong effort to reintroduce the threatened fish to its native streams. Like many species in the West, the greenback cutthroat used to be native and thriving in multiple streams in Colorado’s South Platte River drainage, which stretches from the foothills and canyons of the Front Range to high mountain waters near the Continental Divide. 

A Colorado Parks and Wildlife project for years has kept the public away from stretches of Bear Creek in a canyon west of Colorado Springs, where a reproducing population of the fish was discovered in 2012 following on and off speculation the species might be extinct. CPW teams electroshock small pools in Bear Creek to extract eggs (known as roe) and sperm (known as milt) from the fish before returning them to the creek. 

Some of the reproductive material is taken to state and federal hatcheries to develop genetically diverse broodstock. Teams have then taken fingerlings from the hatchery in water-filled backpacks to various promising habitats in the high country — Herman Gulch, Dry Gulch, the west fork of Clear Creek and Williams Gulch. Placing the fish in multiple habitats reduces the likelihood that events ranging from sediment to wildfire to disease pose an existential threat to the species.

But until now, the Bear Creek greenbacks have been closely guarded as the only self-sustaining population. CPW aquatic biologist Cory Noble led a team last spring that strapped on electrofishing backpacks and battled thick underbrush as they worked their way up the creek collecting fish for the project.

Seeing the results of that ongoing effort proved especially gratifying.

“It’s definitely highly rewarding to see that we’re making a difference now and that we have more than one population that we’re actually making headway in restoring that species out on the landscape,” Noble said. “It is kind of my life’s work, and this makes it seem all worthwhile.”

This 12-inch greenback cutthroat trout was among those found in a recent survey of Herman Gulch by Colorado Parks and Wildlife aquatic biologists. They also found greenback fry, meaning adult greenbacks had naturally reproduced in the wild for the first time since CPW began stocking them in 2016. (Courtesy of Colorado Parks and Wildlife)

Although Bear Creek no longer holds the distinction of harboring the only self-sustaining population of greenback cutthroat trout, Noble said he does not expect any changes in the management of the drainage that might loosen restrictions for hikers or bikers. 

“We’re still quite a number of years off from having fully restored greenback cutthroat trout populations throughout the state,” he said. “So I think that Bear Creek does remain critical for the recovery of the species.”

Workers at the Mount Shavano State Fish Hatchery in Salida and the Leadville National Fish Hatchery also celebrated the Herman Gulch discovery after spending years on the often difficult work of nurturing the broodstock — a smaller population raised in optimal conditions for breeding and eventual dispersal. Genetic material extracted from cutthroat in Bear Creek makes quite a journey before its fingerlings find their way to waterways that might be conducive to their survival.

Generally, Bear Creek yields few eggs, but the milt from the males gets transported to Salida, where workers relay it to Leadville, where it’s introduced to eggs, which then return to the Salida hatchery to grow. The survival rate is notoriously low — about 10%, said Bryan Johnson, manager of the Salida hatchery.

“We spend a lot of time counting eggs,” said Johnson, leader of the seven-person crew at the hatchery. “It’s a yearlong process to produce the fish that actually go back into our broodstock. It takes about a (full time equivalent) every year to work on these cutthroats. A lot of times, it hasn’t always been rewarding. Now to see this, it makes everybody happy to see the goal come to fruition after all these years.”

Thriving trout are an indicator of a healthy watershed, while loss of trout is an early warning sign of a declining stream, Nickum said. Declines of fish and flies for their food on the Colorado River near Granby prompted years of work resulting in the recent groundbreaking for reconnection of the river at the Windy Gap dam, which had disrupted natural water flows. 

More habitat for the greenback cutthroats broadcast from Bear Creek origins is on the way in Lost Creek Wilderness, once state officials make sure a stream there that is part of the South Platte River drainage is free of whirling disease, Nickum said. Other greenback cutthroat projects supported by Trout Unlimited are at various stages at the headwaters of the Cache la Poudre River in northern Colorado, where CPW has developed additional broodstock. 

Joe Bushyhead, an endangered species attorney with WildEarth Guardians, called news that the greenback cutthroats have begun to reproduce in Herman Gulch heartening. But he said the work to restore the state fish is not done. “These native fish have a long path to recovery in the wild, and news of a reproducing population marks progress.”

Kevin Simpson

Kevin Simpson

Kevin Simpson is a co-founder of The Colorado Sun and a general assignment writer and editor. He also oversees the Sun’s literary feature, SunLit, and the site’s cartoonists.

Michael Booth

Michael Booth is a Colorado Sun reporter covering health, health policy and the environment. Email: booth@coloradosun.com Twitter: