Wildlife officials: Greenback cutthroat trout back from the brink
After over a decade of intensive efforts to rescue the greenback cutthroat trout from the brink of extinction, Colorado Parks and Wildlife announced on Sept. 23 that it discovered 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 huge breakthrough by Parks and Wildlife’s aquatics team. Since 1937, the agency 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 Herman Gulch discovery marks a major milestone.
In 2012, Parks and Wildlife confirmed that Bear Creek, a tributary of the South Platte, was home to an unlikely population of wild greenback. The fish are believed to have been brought to Bear Creek from the South Platte Basin in the late 1800s for a tourist fishing enterprise.
The discovery triggered a massive effort by Parks and Wildlife and the Greenback Recovery Team — a multi-agency group of state and federal aquatic researchers and biologists — to protect the 3.5-mile stretch of water holding the only known population of naturally reproducing greenbacks and then locate them in their native home of Herman Gulch.
“This is a huge wildlife conservation success story and a testament to the world-class wildlife agency Coloradans have in Colorado Parks and Wildlife. Colorado’s ecological diversity strengthens our community, supports our anglers, and our thriving outdoor recreation economy,” said Colorado Gov. Jared Polis. “(Parks and Wildlife’s) staff and our partner agencies have worked for more than a decade to restore this beloved state fish, and today’s news truly highlights the success of the work.”
The governor’s thoughts were echoed by officials throughout Parks and Wildlife, including front-line aquatic researchers and biologists.
“I am so proud of all the aquatic researchers, biologists, hatchery staff, volunteers and partner agencies who helped achieve this milestone of naturally reproducing greenback cutthroat trout,” said Parks and Wildlife Acting Director Heather Dugan. “Despite more than a decade of setbacks and frustrations, (Parks and Wildlife) staff worked as a team across departments and regions, stayed focused on the goal and now we gave this great news.”
In the years since the 2012 confirmation of greenbacks in Bear Creek, Parks and Wildlife has worked with its partners to protect and improve the creek habitat to develop a “broodstock” — a small population kept in optimal conditions in a hatchery to maximize breeding and provide a source of fish for the establishment of new populations.
Each spring, aquatic biologists have strapped on heavy electro-fishing backpacks to painstakingly hike up Bear Creek to catch greenbacks and collect milt and roe — sperm and eggs. They use the milt to fertilize all the roe in a makeshift lab on the creek’s bank. The spare greenback milt is then raced to Colorado’s National Fish Hatchery outside of Leadville to fertilize eggs from the greenbacks in its broodstock. All fertilized eggs are then kept in a greenback isolation unit where optimal conditions allow the maximum number of eggs possible to hatch.
In 2016, Parks and Wildlife began stocking the greenback fry, or baby fish, that hatch from those eggs into Herman Gulch and other native streams. Today, fledgling greenback populations exist in four other streams, but only fish in Herman Gulch have lived long enough to begin reproducing.
Parks and Wildlife and its partner agencies have carried bags of greenback fry miles up steep mountain trails every summer since, trying to get them into water where they might reproduce.
“Aquatic biologists in the Southeast Region have worked incredibly hard to protect and preserve the only known population of greenbacks in Bear Creek,” said Josh Nehring, Parks and Wildlife’s assistant aquatic section manager. “Now to see them on the landscape in their native habitat replicating on their own is a huge sense of accomplishment for everyone involved.”
The news of reproducing greenbacks in Herman Gulch was never a sure bet. Over the years, aquatic biologists feared they could lose the population in Bear Creek. There was intense pressure from increased recreation and traffic in the area, delivering sediment into Bear Creek. Flash floods occurred that could have wiped out the rare trout. Invasive, aggressive brook trout remain a threat to outcompete the greenbacks. Wildfires have even erupted in forests that surround the creek.
In 2020, Parks and Wildlife aquatic biologist Cory Noble launched even greater efforts to modify the habitat to reduce the influx of sediment, to patrol for invasive brook trout, and to monitor the population by using underwater cameras.
While Noble worked on Bear Creek, many of his aquatic colleagues spent countless hours hiking miles of High Country streams in the gritty work of identifying host creeks, preparing them for greenbacks and then hauling them miles in backpacks to be stocked at Herman Gulch.
Bob Wright, an aquatic biologist in Fort Collins, led the effort. After some disappointments, on Sept. 23 they made a stunning discovery: they documented greenbacks up to 12 inches long and found fry.
“Our team of field technicians literally high-fived right there in the stream when we captured that first fry that was spawned this year,” Wright said. “When moments later we captured a one-year-old fish produced in 2021, we were truly beside ourselves.”
In late September, a Parks and Wildlife team led by hatchery manager Bryan Johnson bagged greenback fry in early morning hours so they could drive the fish 11 hours up gravel roads to a new reintroduction site. There, the team handed off the fish to the Northeast Region team.
“This is just the start,” Johnson said. “We need more. We’ve only got a few places where we have greenbacks on the landscape. But it’s awesome to see natural reproduction in Herman Gulch. We’ve gone through a lot to get these fish back on the landscape.”
Harry Crockett, Park and Wildlife’s native aquatic species coordinator and chair of the Greenback Recovery Team, said he’s confident the news of natural reproduction in Herman Gulch will be followed by even better headlines.
“We found a greenback that was born in Herman Gulch that was already a year old,” Crockett said. “This indicates successful reproduction both this year and last, plus overwinter survival. … With more of these reintroductions going, we expect to find more reproduction in more places in the coming years.”
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