Stocking greenback cutthroat trout into the Poudre River tributary system — @COParksWildlife

Covid-Mask-wearing Black Bear. Credit: Colorado Parks & Wildlife

From Colorado Parks & Wildlife (Jason Clay)

A multi-agency effort to restore the federally threatened greenback cutthroat trout into its native river basin took a giant hike upwards last week when an army of Colorado Trout Unlimited volunteers led by Colorado Parks and Wildlife and U.S. Forest Service staff stocked the Colorado state fish into a new body of water.

Around 10 staffers and 40 volunteers from Colorado Trout Unlimited each hiked between 12-15 greenback cutthroat trout in backpacks into a Poudre River tributary stream. This introduction marks just the fifth body of water in the state the greenbacks now can call home, with four of those five within the South Platte River basin that the greenbacks are native to.

“Today is one of those exciting instances of getting a new population established,” said Kyle Battige, Aquatic Biologist with CPW. “We are trying to replicate and perpetuate this resource across the landscape, by getting greenbacks into more water bodies within the South Platte River basin.”

A total of 711 greenbacks were stocked on Tuesday, July 28. They came from the Mt. Shavano Hatchery out of Salida. It took the hatchery one year to take the fertilized eggs, hatch and raise the fish to five inches in length, primed for release into the wild.

“Colorado Trout Unlimited is a proud partner in the campaign to protect and restore our native trout,” said Dan Omasta, Grassroots Coordinator for Colorado Trout Unlimited. “This stocking project is another great example of how anglers and local communities can work together to save a threatened species. We had over 40 volunteers that traveled from as far as Eagle, Colo., and Wyoming to carry fish over nine miles into the backcountry on a rainy afternoon. The passion and dedication of our community is what drives an optimistic future for the greenback cutthroat trout.”

U.S. Forest Service personnel located the fishless stream in the Poudre River basin a couple years ago and the agencies did their due diligence to make Tuesday’s stocking become a reality. Aquatic biologists conducted stream sampling with backpack electrofishing units and took eDNA samples to confirm it was indeed a fishless location. Habitat suitability work also took place to ensure the fish would survive once stocked. Everything checked out and the greenbacks were stocked into a fifth body of water in Colorado.

“We’re excited and proud to be partnering with CPW on this important effort reintroducing greenback cutthroat trout and restoring part of Colorado’s natural heritage,” said Christopher Carrol, Fisheries Biologist and Watershed Crew Lead with the Arapaho and Roosevelt National Forests and Pawnee National Grassland. “We especially want to thank Colorado Trout Unlimited and Rocky Mountain Flycasters Chapter of Trout Unlimited for organizing so many passionate volunteers and helping collect data that informed our decision for making the reintroduction. Shared stewardship and working together pays dividends for native species.

An important characteristic when looking to identify a reintroduction site is that the stream must be fishless. It must also have protection from invasion of non-native trout that will outcompete and overrun the greenbacks.

“This location is protected by a series of natural waterfall barriers, upwards of 20-feet, that ensures the reach we stocked will not be invaded by non-native fish downstream,” Battige said.

Cutthroat trout historic range via Western Trout

The greenbacks have previously been stocked into Herman Gulch, Dry Gulch, and Zimmerman Lake – all within the South Platte River drainage. These rare fish, twice believed to be extinct, are descendants of the last wild population of native greenback cutthroat trout found in Bear Creek outside of Colorado Springs in 2012. Bear Creek is the fifth body of water in Colorado where the fish currently reside.

“This project could not have been completed without the hard work and dedication of today’s volunteers. The hikes that they did range from four miles roundtrip up to nine miles and covered 1,200 to 2,400 vertical feet of elevation, so it was a pretty substantial undertaking,” Battige said.

The fish were loaded onto the hatchery truck at 3:30 a.m. and driven roughly 240 miles to the trailhead where they got loaded into bags with 1-2 gallons of water and pumped full of oxygen. The fish were put in ice water before leaving the hatchery, so they can handle the conditions better during their long journey.

“Lowering the temperature helps the fish travel well, ensures that their metabolism slows down and decreases the overall stress on the fish,” Battige said.

The water temperature in the stream was 51 degrees, so before getting stocked the volunteers tempered their fish, meaning they took time to slowly acclimate the fish to the temperature in the creek over a 10-15 minute time period.

Crews will stock additional greenbacks into the same location each summer for the next two years as they look to establish the population. They will follow up with surveys to see how the fish are doing and aquatic biologists will look for signs of natural reproduction and new greenbacks hatching in the stream in 3-4 years.

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