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While firefighting crews were in the throes of battling the 416 Fire as it rapidly spread through the San Juan National Forest north of Durango in June 2018, an unlikely rescue mission was being hatched.

Jim White, an aquatic biologist for Colorado Parks and Wildlife, said plans had to move fast as the blaze started inching toward prime habitat for a rare lineage of cutthroat trout that lives in the remote side streams of Hermosa Creek.

Colorado Parks and Wildlife knew what was at risk: the potential loss of a native fish that had survived in isolation, against the odds, through all the disturbances of the West’s settlement.

With a massive wildfire as the latest threat, the survival of these trout depended on a small crew from CPW and the U.S. Forest Service who were granted special permission to enter the fire zone, with only hours to work.

“We couldn’t have anything go wrong,” White said. “But if a fire burned through that drainage, you could lose an entire population and those genetics.”

Now, two years later, the fish saved during the rescue will be released back into the wild.

Surviving the decadesBy the late 1880s, Western settlers fished the Colorado River cutthroat trout to the point of extinction, and then dumped more competitive species of trout into rivers and streams to keep the food source available.

The magnitude of the cutthroat’s loss has never been truly quantified, but best estimates show its range – which once spanned Colorado, New Mexico, Utah and Wyoming – has been cut by about 85%.

For the past 50 years, CPW biologists have scoured the backcountry looking for surviving populations of cutthroats. In the 1980s and 1990s, fish suspected of fitting the bill were discovered in eight small streams in Southwest Colorado.

But at the time, technology didn’t exist to say for sure.

In 2018, however, DNA testing confirmed those suspicions, linking a cutthroat found in the San Juan River basin to fish samples collected and preserved in 1874 by naturalist Charles E. Aiken, who donated two trout to the Smithsonian National Museum of Natural History.

“It was super-exciting,” Mike Japhet, a retired CPW biologist who helped discover the San Juan lineage of Colorado River cutthroat trout in the early 1990s, told The Durango Herald at the time. “It’s like going on a treasure hunt and finding you really discovered a hidden treasure.”

Rescue missionEveryone knew summer 2018, with its historic drought conditions, was going to be a bad year for wildfire, White said. In preparation, the groundwork for trapping some of the cutthroats in the Hermosa Creek watershed was laid the winter before.

“We knew a fire was a distinct possibly where one of these rare streams are and it could be terrible,” he said.

So when a small spark north of Durango ballooned into the 54,000-acre fire that swept through the drainage, crews were ready to go. A small team of about seven people started early, taking ATVs as far into the backcountry as possible.

After the road ended, crews hiked 2 miles to reach the remote stream. Once there, they had three hours to catch as many fish as possible before having to escape the area before nightfall.

“It was spooky,” White said, recalling the fire burning off in the distance. “It had to be carefully orchestrated.”

Despite the odds, 54 cutthroats were recovered.

“The next day, the fire mushroomed, and we would never have been allowed back there,” White said.

Wild struggles in captivityThe fish were brought back to the hatchery in Durango where they have been kept in isolation. At first, biologists were concerned because the fish did not spawn last year and some died of a parasite.

This year, however, CPW hit a stroke of luck.

“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,” Durango Hatchery Manager Toby Mourning said in a statement.

This summer, CPW intends to trek the fish back to their native habitat and release them into the wild. And with the captive population at the hatchery, the agency can start to restock other streams throughout the Southwest.

“If we hadn’t saved them, we would have seen substantial loss,” White said. “But now we can expand their range.”

Recovering, slowlyBy all accounts, aquatic biologists are hopeful reintroduction will be successful.

The 416 Fire has had substantial impact on water quality in the Hermosa Creek watershed, causing several debris flows and fish kills, especially in July and September 2018 when heavy monsoons hit the burn scar.

But slowly, the watershed is showing signs of recovering, said Scott Roberts, an aquatic biologist for Mountain Studies Institute, which is leading a robust study tracking water quality after the 416 Fire.

Watersheds usually take about three to five years to recover after a wildfire compromises the drainage. Roberts said all indicators point to Hermosa Creek being on track for that time frame.

“The impacts are highly localized, some areas were hard hit and the habitat transformed, while other places are trending toward pre-fire conditions quickly,” he said. “But I feel confident there are areas fish can be successful up there.”

The upper reaches of Hermosa Creek boast the largest continuous stretch of native Colorado River cutthroat trout in the state thanks to a dedicated conservation effort that dates back to the early 1990s

“The watershed is not perfect, but it’s stabilized, and we feel we can responsibly move fish up there,“ White said. “This is definitely a one small step at a time process, but we’re excited to have some fish to work with.”

jromeo @durangoherald.com