Green trout, Colorado’s state fish once thought to be extinct, are now thriving in their native pond, Gov. Jared Solis announced Friday.
The state of Colorado has succeeded “again, again” in efforts to restore cutthroat trout to their native range within the South Platte River watershed. A genetically pure population of fish was found in Bear Creek on the slopes of Pikes Peak in 2012 in the Arkansas River drainage—the fish were likely planted there more than a century ago by a mountain lodge owner to create a recreational fishing for visitors. Prior to this, other relict populations were found and stocking efforts were underway as early as the early 2000s. Unfortunately, the spawning stock for those earlier efforts turned out to be genetically contaminated with Colorado River cutthroat trout ancestry.
But last week, Colorado Parks and Wildlife announced that the first-ever documented spawning of greenbacks from the genetically pure Bear Creek line has occurred in Herman Gulch west of Denver.
“While we will continue to stock greenback trout from our ponds, the fact that they are now successfully reproducing in the wild is exciting for the future of this species,” Solis said Friday. “This is a great wildlife conservation success story and a testament to the world-class wildlife agency Coloradans have at Colorado Parks and Wildlife. Colorado’s ecological diversity strengthens our communities, supports our fishermen and our thriving economy.” of outdoor recreation. CPW 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.”
Green boxes were declared extinct from Colorado in the mid-1900s, victims of mining, road building, logging and general human development. But biologists and fisheries professionals never lost hope. After initial successes and failures with tainted birds initially released into waters within the South Platte and Arkansas drainages, the discovery of a new generation of greenbacks emerging in the wild marks a major milestone in the fish’s recovery.
A green fry captured from Herman Gulch (photo: CPW).
To this day, a three-mile stretch of Bear Creek remains the last true bastion for these fish and is the source of the babies for Colorado Parks and Wildlife’s recovery efforts. Each year, biologists catch spawning trout in Bear Creek, collect eggs and mealybugs, and then collect the greenbacks at the Leadville National Baby Fish Hatchery. In 2014, CPW established a second spawning stock at Zimmerman Lake, near the headwaters of the Cache la Poudre River and within the fish’s native range. Together, the two resources are used to raise the fish and then stock them into waters within their native range where CPW believes the fish can reproduce and thrive.
“The fundamental mission of Colorado Parks and Wildlife is to perpetuate the state’s wildlife resources,” CPW Acting Director Heather Dugan said in a news release. “Despite more than a decade of setbacks and disappointments, CPW staff worked as a team across departments and regions, stayed focused on the goal, and now we deliver this great news. It’s a great day.”
Green money was first collected in Herman Gulch in 2016. A tributary of Clear Creek, which crosses I-70 between Georgetown and Golden, Herman Gulch begins on the shoulders of the Continental Divide and is accessible only by foot. Three other streams within the South Platte drainage have also been stocked with greenbacks, but only the Herman Gulch population has been in the wild long enough to mature and spawn.
It may seem like a small thing—taking clean cut trout from one stream and putting them in another—but the restoration effort has been fraught with danger from the start. Biologists have had to contend with wildfires, flash floods and reports in 2020 that the Bear Creek population of greenbacks was declining and that no natural reproduction occurred that year. CPW immediately went into action to improve the habitat in the spawning stream. Additionally, threats constantly exist from non-native trout such as rainbow, brown and brook trout that may move into green habitat and out-compete native fish.
After all the mishaps, it was a relief for biologists and technicians to find the red fry in Herman Gulch this summer.
Alex Burks, a CPW aquatics technician, weighs an adult greenback trout during a recent CPW survey of Herman Gulch west of Denver (photo: CPW).
“Our team of field technicians literally went down the river when we caught the first fry to spawn this year,” said Boyd Wright, a CPW aquatic biologist based in Ft. Collins. “When moments later we caught a yearling fish produced in 2021, we were really beside ourselves. After many years of hard work and dedication, it is extremely satisfying to see our efforts paying off.”
Overall, fish shocked at Herman Gulch ranged from young-of-the-year fry to cutthroats up to a foot long—likely fish from the original Bear Creek plan. Yearling fish were also found, indicating that, at the very least, cutthroat trout have been spawning in Herman Gulch since 2021.
“This is important because trout that survive up to a year will likely live longer,” said Harry Crockett, aquatic native species coordinator and chairman of the state’s Greenback Recovery Team.