WESTCLIFFE— Tuco the mule sidestepped and bolted up the trail, spooked by the sloshing water and fish strapped to its back.
The young mule calmed a few minutes into the climb up Cottonwood Creek, a 5-mile trek to bring thousands of 4-inch cutthroat trout to their new home.
Tuco and a second, more experienced mule called Jenny — along with nearly 40 volunteers and workers from Colorado Parks and Wildlife and the U.S. Forest Service — carried 4,500 trout up a mountain Monday and released them into the rushing, whitewater creek above Westcliffe in south central Colorado.
The fish are the descendants of a unique species of cutthroat trout rescued from Hayden Creek in 2016 as a wildfire ripped through the Sangre de Cristo mountains, scorching nearly 17,000 acres near Coaldale.
In 2016, as the fire burned only a quarter-mile away, parks and wildlife fish biologists led by a fire crew hiked behind the fire line to remove about 200 of the fish from Hayden Creek. Wearing electrofishing backpacks, they shocked the water and waited for the stunned fish to float, netting as many as they could.
The biologists knew that particular type of cutthroat trout lived nowhere else but Hayden Creek and that the ash-filled runoff after the fire likely would kill them.
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They were right. Monsoons that followed the fire sent ash and sediment into Hayden Creek, which turned the water acidic and depleted its oxygen. The remaining cutthroat suffocated. When biologists returned after the rains, they could not find one fish.
Trout rescued from Hayden Creek were taken to a hatchery near Gunnison, where they were isolated from other subspecies. Some were released in Newlin Creek, near Florence, and this week, 4,500 of their offspring were loaded into a hatchery truck headed for Westcliffe.
At the trailhead in the shadow of the jagged peaks of the Sangre de Cristos, a Colorado Parks and Wildlife crew used a net to scoop up dozens of trout at a time from the tank of the hatchery truck and into cooler-sized panniers strapped to the mules. The rest went in plastic bags that were tucked into hikers’ backpacks.
Aquatic biologist Carrie Tucker hopped on the flatbed of the hatchery truck to shout instructions as dozens of hiking volunteers gathered at the Comanche Trailhead. Spread out along the trail, she told them. Find an eddy or a pool in the creek, then set the bag of fish in the stream for 10 to 15 minutes to let the trout adjust to the temperature before opening the bag and releasing the fish, Tucker said.
Earlier that morning, Tucker sent a runner up the trail to take the temperature of Cottonwood Creek — a cool 42 degrees. The water in the hatchery truck rolled in at 46, so Tucker’s crew added ice to the bags of fish as they were loaded onto mules and into backpacks.
Besides the orange coolers of fish strapped on like saddlebags, the mules carried oxygen tanks. The fish were so densely packed in the water, they needed extra oxygen. And the parks and wildlife crew topped off each bag of fish in a backpack with a shot of oxygen.
Melanie Cypher and James Patterson, residents of Westcliffe, signed up to help with the trout expedition after previously volunteering with the Forest Service to clear trails. They were told to expect 15 to 20 pounds each of water and fish on their backs and not to put the baby trout in fast-flowing water. “We’ve got to give the little guys a chance,” Cypher said.
So many volunteers showed up to help, not everyone ended up carrying fish. They went along for the hike anyway, past pink wild roses and a stunning view of the valley below.
About 2 miles up the trail, senior aquatic biologist Josh Nehring carried his plastic bag of trout to a pool at the bottom of a small waterfall. As his bag sat in the stream, Nehring pulled out a baby cutthroat and laid it across the palm of his hand.
The fish, with orange-red splotches on its throat and across its belly, is hardly distinguishable from other cutthroat trout. Yet, the Hayden Creek cutthroat trout are the only fish known to share the genetics of a pair of fish now at the Smithsonian Institution in Washington, D.C. The fish were caught in Twin Lakes, near Leadville, in 1889 by an ichthyologist — the type of zoologist that studies just fish — named David Starr Jordan.
Colorado has three remaining subspecies of cutthroat trout that are native to the state: the greenback, the Colorado River and the Rio Grande. A fourth native cutthroat, the yellowfin, is presumed extinct.
The Hayden Creek cutthroat are part of the Colorado River subspecies, but have genetics unique even from Colorado River cutthroat.
Nehring released his fish one at a time Monday and watched afterward as they darted around in the clear water. Even at 4-inches long, they held their own against the current.
A parks and wildlife team will return in the fall to check on the trout, using electrofishing to catch and measure them. The hope is that they not only will survive, but will begin reproducing in about two years.
They will fill an important niche in the ecosystem, Nehring said. The fish eat mayflies, stoneflies, caddisflies and worms, and are food for bears, raccoons and other animals.
“These fish were here before man was here and many of the problems we’ve had with cutthroat hybridizing and the reduction of native fish is due to man,” Nehring said. “I think it’s important for us to work hard to preserve those native fish.”
Monday’s trout expedition was part of an increased effort by Colorado Parks and Wildlife to restore native fish after decades of man messing with nature. In the late 1880s and early 1900s, many of Colorado’s native fish and fish eggs were shipped on trains to stock rivers and lakes across the state. Spawning operations sent fish eggs to every county in Colorado that had water to hold them, Nehring said.
In recent years, thanks to genetic technology and university-based research that identified subspecies of cutthroat, aquatics biologists have refocused their efforts on separating the fish to reduce hybridization. With some restoration efforts, biologists first remove all other fish from a stream before releasing a native fish.
In the case of Cottonwood Creek, that wasn’t necessary. That’s because the mountain stream had none.
The creek “went fishless” in 2012, Nehring said, after severe drought dried it up into shallow pools, and the water was too warm for fish to live.
That was hard to imagine this week, as the creek roared down the mountain. Cottonwood Creek was an easy choice for the cutthroats’ new home because it had no fish, but for the trout to survive here, the stream will have to keep flowing.