After nearly a two-year wait, Colorado Parks and Wildlife hatchery staff and biologists in Durango have spawned a new lineage of Colorado River cutthroat trout that were rescued from a remote stream during the 416 Fire in 2018.
This marks a major milestone for CPW’s on-going species conservation work in Colorado, and the result of decades of work by dedicated biologists, researchers and field staff.
Fertilized eggs of the San Juan cutthroats will hatch by mid-summer; some of the fingerlings will be placed in back-country streams in the southwest area of the state and others will be held at the Durango hatchery to start a sustainable brood stock. Now, the hatchery staff and biologists will continue the long-term effort to restore these native trout to their home waters.
“I’m thrilled that we’ve gotten a spawn from these fish, it’s been a long process and we’ve got a lot more work to do,” said Jim White, aquatic biologist for CPW in Durango.
The story of these fish that hold a unique genetic marker goes back nearly 150 years and includes some serious biological detective work. Since the 1970s, CPW aquatic biologists have searched back-country streams looking for isolated populations of cutthroats — Colorado’s native trout. In southwest Colorado in the 1980s and 1990s, biologists found cutthroat trout that were suspected to have unique characteristics in eight small streams. Back then, however, technology to analyze genetics fully was still being developed. The biologists kept their eyes on the fish and made sure non-native trout were not stocked nearby.
In 2012, researchers from the University of Colorado went to the Smithsonian National Museum of Natural History looking for preserved specimens of cutthroat trout that had been collected in Colorado. Two of the specimens they found were taken from the San Juan River near Pagosa Springs in 1874.
An analysis showed that the fish had genetic “fingerprints” specific to the San Juan River Basin. CPW researchers then began a similar analysis of the cutthroats they’d found in southwest Colorado. By this time, genetic-analysis technology had advanced and in early 2018 scientists confirmed that the marker in the museum specimens matched the cutthroat trout recently found in the wild.
Biologists and hatchery staff then made a plan to start propagating the fish. The 416 Fire helped push the project along.
When the fire started north of Durango, biologists worried that ash and sediment run-off could kill the cutthroats in the remote streams. So CPW worked with the San Juan National Forest to go into the area to capture the wild trout and bring them to a special isolation hatchery in Durango. Only 54 cutthroat were recovered from the fire area.
White and Durango Hatchery Manager Toby Mourning have been concerned because the fish did not produce any spawn last year and some of the fish died. But the turnaround this year is a major milestone for the restoration effort.
“We’re not getting a lot of eggs, but enough to provide some for a limited amount of stocking and some to start a captive population that will be sustainable,” Mourning said.
In order to protect the fish, CPW is not providing details on stream locations. Biologists hope, however, that in a few years anglers will be able to find this unique cutthroat trout in the wild.
White explained that the work on this native is a significant conservation effort. In 2018, after the genetics of the fish were confirmed, he said: “We always ask ourselves, ‘What if we could go back to the days before mining, pioneer settlement and wide-spread non-native fish stocking to see what we had here? Careful work over the years by biologists, finding those old specimens in the museum and the genetic testing gave us the chance, essentially, to go back in time. Now we have the opportunity to bring this native trout back to southwest Colorado.”
Written by Joe Lewandowski. Joe is the public information officer for CPW’s Southwest Region. He’s based in Durango.