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Plan would use poison to restore Yellowstone cutthroat trout in Bighorn Basin

Dave Sweet, a board member of the East Yellowstone chapter of Trout Unlimited, shows off a Yellowstone cutthroat trout he caught at the end of June, 2018 in the Thorofare region of Yellowstone National Park. (Diana Miller)

September 21, 2021 by Angus M. Thuermer Jr.WyoFile

Wyoming has launched a long-range plan to restore Yellowstone cutthroat trout to the Bighorn Basin and make parts of five watersheds the sensitive species’ exclusive domain.

The Game and Fish Department earlier this year completed a conservation plan for the basin east of Yellowstone National Park that includes poisoning fish in the select drainages as part of Yellowstone cutthroat restoration. Non-native cousins like brook and rainbow trout are “the greatest threat” to Yellowstone cutthroat and “the greatest impediment” to their conservation, Game and Fish states in its plan.

Because rainbows cross-breed and produce hybridized “cut-bow” offspring, preserving true Yellowstone cutthroat requires maintaining numerous populations that are isolated from other species. “Headwater isolation” is the agency’s preferred method of achieving the goal.

The strategy will employ existing natural fish barriers and would require construction of at least one man-made barrier. Ultimately, Yellowstone cutthroat would exist exclusively in the upper reaches of five Bighorn sub-basins, including in four “meta populations” where a series of tributaries and even lakes would be home to a thriving community.

“I think this will be multiple decades in the making,” said Sam Hochhalter, regional fisheries supervisor with the Game and Fish Department in Cody. His office undertook a two-year public engagement effort to incorporate regional ideas into the plan, with good result, he said.

While Game and Fish has decades of wildlife statistics from the Cody region, Hochhalter said, it has only three biologists. “The folks who participated… represent centuries of knowledge,” he said. “They offered up projects that were not on our radar.”

A beautiful fish

There are many reasons for preserving Yellowstone cutthroat trout, including that they were considered for protection under the Endangered Species Act in the 1990s. Although the U.S. Fish and Wildlife Service did not extend federal protection to the species, Yellowstone cutthroat remain troubled due to habitat degradation, hybridization and competition from non-native fish.

Beyond that, “Yellowstone cutthroat trout will eagerly come to the surface for a dry fly,” Hochhalter said. “It’s a pretty fun way to go about fishing.

“They are a beautiful fish; the coloration on them is exquisite,” he said, referring to a hue often called “buttery.” Too, they exist in a land populated by bighorn sheep, grizzly bears and other symbols of enduring nature.

People value excursions into the mountain landscape that sustains such wildlife, “knowing that the fish have been swimming in these streams for thousands of years,” he said.

Game and Fish, however, must be sensitive to anglers who value all wild fish, regardless of whether they are native. Back and horse packers, for example, love brook trout because of their abundance and the ease with which they can be caught and made into a meal.

“Anglers,” Hochhalter said, “like that aspect of fishing for brook trout.”

But one guide who plies Yellowstone cutthroat waters — Jackson’s Jean Bruun of Wyoming Angling Company — said sometimes agencies and bureaucracies focus too much on one aspect of a problem.

“It’s easier to identify a single enemy and try to rally all your resources and funding and processes to fight that one foe,” she said. “I think what we have come to know is there [is] a lot more than one enemy.

“I love and celebrate our indigenous [trout], but I love and celebrate [all] our wild populations,” she said. For more than 100 years in the Yellowstone area, she said, natives and non-natives “have been able to live side by side.”

Bruun’s respect for all wild game fish and reluctance to immediately point the finger at other species are views shared with her husband, a guide and newspaper columnist. The plight of the Yellowstone cutthroat  has “[e]very green activist, troutie, aquatic and armchair biologist, sporting goods peddler, chamber of commerce type, outdoor editor, reporter and professional fundraiser … clamoring,” Paul Bruun wrote in the Jackson Hole News&Guide in 2014. 

Public clamor

Clamor is what Game and Fish heard when it sought to implement the first of its restoration initiatives a few years back, Hochhalter said. Game and Fish was operating under a multi-state, multi-agency agreement forged in 2000 after federal biologists found ESA protections unnecessary. Yellowstone cutthroat historically occupied parts of Wyoming, Montana, Idaho and Utah.

The interstate group continued to work past that federal decision, Hochhalter said, but found that the public was skeptical about poisoning and removing other species. “We were under some scrutiny suggesting Game and Fish was out to remove [too many] non-native trout, that we just didn’t like brook trout,” he said.

This Game and Fish map depicts the five drainages, shaded, where isolated populations of Yellowstone cutthroat trout would have exclusive headwaters domains. (Wyoming Game and Fish Department)

The agency formed a working group of area residents with transparency as a goal. “We asked the public what their interests and concerns were,” Hochhalter said. “We left it up to them to learn about the logistics, point us in the direction of what they thought would be [the best] restoration.”

Ideas gathered from seven workshops involving 176 participants, including members of the East Yellowstone chapter of Trout Unlimited, helped produce the plan. After reading scientific literature, resistance to poisoning among members of the working group diminished, Hochhalter said. It took Game and Fish another two years of field work, however, to confirm that working-group proposals had merit.

Most importantly, the plan earmarks parts of the Bighorn Lake, Clarks Fork of the Yellowstone, Nowood, North Fork of the Shoshone and the South fork of the Shoshone drainages as exclusive Yellowstone cutthroat preserves. In each of the five sub-basins, Yellowstone cutthroats will thrive in either five smaller isolated populations or a “meta” population. Meta populations include several tributaries in which the species’ natural lifestyle – including aspects like migrations and spawning – is represented.

All told, the plan would increase exclusive Yellowstone cutthroat stream habitat by about 125 miles, growing the domain from 185 miles to 310 miles in the basin. The plan would increase exclusive Yellowstone cutthroat lakes by 13, increasing the number from four to 17.

The exclusive Yellowstone cutthroat lake acreage would expand from 56 to 355 acres, an increase of 299 acres, according to calculations made from the state plan. In the end the Bighorn Basin would be home to 16 isolated populations and four meta-populations, an increase of nine and two respectively.

Without the help of humans, “the current cutthroat trout populations cannot be considered secure or likely to persist over the long term,” according to scientific research.

Swimming across the Continental Divide

In addition to its colorful cutthroat slash and ruddy cheeks, the Yellowstone cutthroat is notable for havingswum over the Continental Divide, perhaps over Two Ocean Pass in the Teton Wilderness, according to scientists’ reckonings. Originally a Pacific drainage species, The only places where the species naturally existed in the Atlantic drainage was the Yellowstone River drainage, parts of Montana and the Bighorn Basin.

Flashy colors and historic migrations aside, the species plays an important role in the ecosystem, providing food for 16 species of birds and mammals, including grizzly bears. Once the dominant fish species in Yellowstone National Park, numbers have declined.

Fishing guide Jean Bruun shows off a fly at the start of a trip on the Snake River. (Angus M. Thuermer, Jr./WyoFile)

The illegal introduction of lake trout into Yellowstone Lake decimated a stronghold, according to the National Park Service. The number of Yellowstone cutthroats spawning in the Clear Creek tributary declined from 70,000 in 1978 to 538 by 2007, Yellowstone biologists say.

Under the plan, Game and Fish would poison headwater sanctuaries, then place genetically pure Yellowstone cutthroat back in the isolated segment. Conservationists seek resiliency, representation and redundancy in such species-saving plans. Those parameters help ensure a species persists, that it is genetically diverse and uses the landscape in the way it evolved, and that a single, localized adverse event won’t spell its demise.

Game and Fish investigated nine basins before it chose the five targeted watersheds where Yellowstone cutthroat were struggling, where physical barriers could isolate them from non-native species and where the public has access.

In many locations, natural waterfall barriers exist. But one reach would require a man-made structure and more resources to accomplish, which take longer to achieve.

For guide Jean Bruun, the Game and Fish plan appears to be an appropriate balance. “We have dipped our shoes in many waters,” she said, summarizing how international commerce and travel have spread exotic and invasive species around the world.

For a successful plan, however, Game and Fish can’t impose a doctrine across an expansive area. “Game and Fish has to look at a watershed individually,” she said. “You can’t generalize.”

It is OK for Game and Fish to be “identifying where those [Yellowstone] genetics should be protected,” she said. “We have an opportunity in those small areas.

“If those are habitable zones for those [Yellowstone] fish — removing 100 rainbows from there to keep them from hybridization — I don’t see a problem with that. 

“We do want to do everything we can to protect our wild trout populations,” she said, including brook, brown and rainbow populations. “We love our cutthroats — all of our cutthroats. They’ve been here over 10,000 years and they belong here. They’re my business partner.”

For Hochhalter, forming the working group — the first for a Wyoming fisheries project — spread good information and avoided the prospect of the public drawing conclusions from limited data and stereotypes. Ultimately, all the proposed projects came from the working group, he said. 

The public desires a variety of fishing opportunities and the ability to cast to different species, he said. “Really what they want … is to have the opportunity to fish for all of them.”

This article was originally published by WyoFile and is republished here with permission. WyoFile is an independent nonprofit news organization focused on Wyoming people, places and policy.