Wildlife officials: Greenback cutthroat trout back from the brink

Alex Burks, a Parks and Wildlife water technician, weighs an adult goldenback cutthroat trout during a recent Parks and Wildlife survey of Herman Gulch and confirms the species is thriving.
Colorado Parks and Wildlife/Photo courtesy

After more than a decade of intense efforts to save the goldenback cutthroat trout from extinction, Colorado Parks and Wildlife announced on September 23 that it had discovered that the state fish is naturally reproducing in Herman Gulch in Clear Creek County . This is one of the first places the agency stocked the fish in its native South Platte River drainage.

This is a major breakthrough for the Parks and Wildlife aquarium team. Since 1937, the agency had considered the greenback extinct, having succumbed to pollution from mining, pressure from fishing, and competition from other trout species. After a decade of work to protect and reproduce greenbacks, the discovery of Herman Gulch marks an important milestone.

In 2012, Parks and Wildlife confirmed that Bear Creek, a tributary of the South Platte, was home to an unlikely population of wild greenbacks. The fish are believed to have been brought to Bear Creek from the South Platte Basin for a tourist fishing company in the late 19th century.



The discovery sparked a massive effort by Parks and Wildlife and the Greenback Recovery Team — a multi-agency group of state and federal water scientists and biologists — to protect the 3.5-mile stretch of water that contains the only known population of naturally reproducing Greenbacks houses visit her in her hometown of Herman Gulch.

“This is a huge wildlife conservation success story and a testament to the world-class wildlife authority that Coloradans in Colorado Parks and Wildlife has. Colorado’s ecological diversity strengthens our community, supports our anglers and our thriving recreational economy,” said Colorado Gov. Jared Polis. “The staff at (Parks and Wildlife) and our partner agencies have worked for more than a decade to restore this beloved state fish, and today’s news truly underscores the success of the work.”

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The governor’s thoughts were echoed by officials across Parks and Wildlife, including water scientists and frontline biologists.

“I’m so proud of all of the aquatic scientists, biologists, hatchery staff, volunteers and partner agencies who helped achieve this milestone in the natural reproduction of greenback cutthroat trout,” said Heather Dugan, associate director of Parks and Wildlife. “Despite more than a decade of setbacks and frustrations, (Parks and Wildlife) employees across departments and regions worked as a team, remained focused on purpose, and now we have great news to share.”

In the years since greenbacks were confirmed in Bear Creek in 2012, Parks and Wildlife has worked with its partners to protect and enhance the creek’s habitat to develop a “breeding population” — a small population living in optimal conditions being kept in a hatchery to maximize breeding and supply a source of fish for establishing new populations.

Every spring, aquatic biologists have strapped on heavy electrofishing packs to trek up Bear Creek to catch greenbacks and collect milk and roe — sperm and eggs. They use the milk to fertilize all the roe in a makeshift laboratory on the banks of the creek. The excess greenback spleen is then taken to Colorado’s National Fish Hatchery outside of Leadville to fertilize eggs from the greenbacks in their broodstock. All fertilized eggs are then kept in a Greenback isolation unit where optimal conditions allow for the maximum number of eggs to hatch.

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In 2016, Parks and Wildlife began stocking the greenback fry, or baby fish, that hatch from these eggs in Herman Gulch and other local streams. Today there are still young greenback populations in four other creeks, but only fish in Herman Gulch have lived long enough to begin breeding.

Every summer since then, Parks and Wildlife and its partner agencies have carried sacks of greenback spawn for miles up steep mountain trails to get them into the water where they could breed.

“Water biologists in the Southeast region have worked incredibly hard to protect and preserve the only known greenback population in Bear Creek,” said Josh Nehring, deputy water director for Parks and Wildlife. “Now seeing them replicate themselves in the landscape in their natural habitat is a huge sense of accomplishment for everyone involved.”

This bill was among those found in Herman Gulch in a recent survey by aquatic biologists from Colorado Parks and Wildlife. They also found greenback fry, meaning adult greenbacks had reproduced naturally in the wild for the first time since the agency stocked them in 2016.
Colorado Parks and Wildlife/Photo courtesy

News of the reproduction of greenbacks in Herman Gulch was never a sure bet. Over the years, aquatic biologists feared they might lose the Bear Creek population. There has been intense pressure from increased recreation and traffic in the area, causing sediment to enter Bear Creek. Flash floods occurred that could have wiped out the rare trout. Invasive, aggressive brown trout remain a threat to displace the greenbacks. Forest fires have even broken out in forests surrounding the creek.

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In 2020, Parks and Wildlife aquatic biologist Cory Noble embarked on even greater efforts to modify habitat to reduce sediment inflow, patrol for invasive brown trout, and monitor the population with underwater cameras.

While Noble was working on Bear Creek, many of his water colleagues spent countless hours trekking for miles through High Country creeks to identify host creeks, prepare them for greenbacks, and then backpack them for miles to be stored at Herman Gulch.

Bob Wright, a Fort Collins aquatic biologist, led the effort. After some disappointments, on September 23 they made an amazing discovery: they documented greenbacks up to 12 inches long and found juvenile fish.

“Our team of field technicians were literally giving high-fives right in the creek when we caught the first fry to spawn this year,” said Wright. “When we caught a yearling fish from 2021 shortly after, we were really blown away.”

In late September, a team from Parks and Wildlife, led by hatchery manager Bryan Johnson, bagged greenback fry in the early hours so they could drive the fish over gravel roads for 11 hours to a new release site. From there, the team handed the fish over to the Northeast Region team.

“This is just the beginning,” Johnson said. “We need more. We only have greenbacks in a few places in the landscape. But it’s great to see natural reproduction at Herman Gulch. We’ve been through a lot to get these fish back into the landscape.”

Harry Crockett, Park and Wildlife’s native aquatic species coordinator and chairman of the Greenback Recovery Team, said he was confident that news of natural reproduction at Herman Gulch would be followed by even better headlines.

“We found a greenback that was born in Herman Gulch and was already a year old,” Crockett said. “This indicates successful reproduction both this year and last year, plus winter survival. … As more of these reintroductions take place, we expect to find more reproductions in more places in the years to come.”

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