The great Flathead fish fiasco 

State and tribes disagree over how to handle invasive lake trout

The ding! is soft, but Capt. Rod’s response is Pavlovian, and he skips over to the charter boat’s console with a nimbleness remarkable for a man his size. “Fish on two!” he calls. He hurries back to the stern and pulls the appropriate rod from its sleeve, then hands it to me. “Okay, reel her in,” he says.

I steel myself for battle, but this particular fish, a lake trout, is blasé in the face of death. I reel. It resists a little. I reel again. It tugs, kind of. After a minute or so, Rod scoops the trout out of Flathead Lake and hands it to me. Jim Vashro, an avuncular biologist with Montana Fish, Wildlife and Parks, appraises it with a practiced eye.

“If you want to be respectable, say ‘Less than 10,’” he advises.

He means pounds, and he is certainly right. But respectable or not, my catch is still compelling. It is a prism of a fish: recreational bounty, invasive pest, windfall, scourge, everything between. And it is the subject of a spirited debate about how best to manage the species, not only because of its appetite for threatened fish, but also its absolute dominance here in Flathead Lake and west of the Continental Divide.

Such a fight over a flaccid fish. And here one hangs, its fate in my hands.

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  • Pumpernickel Stewart

Early in the 20th century, biologists believed only 10 species of native fish lived in Flathead, the West’s largest natural freshwater lake. But anglers and game officials had already introduced other species.

“It was a Johnny Appleseed approach,” Vashro says. “Throw in lots of stuff, see what makes it.”

In 1920, a shipment of kokanee arrived from Bonneville, Ore. By 1940, kokanee, which are landlocked sockeye salmon, had replaced cutthroat trout as the most-caught fish, and they remained dominant until the 1980s.

Meanwhile, the lake trout, introduced from the Great Lakes in 1905, bided its time. “There are many cases in which a species arrives and it just sits around,” says Daniel Simberloff, an authority on invasive species at the University of Tennessee. Then, he says, something changes to trigger a rapid expansion. In Flathead Lake, it was Mysis shrimp. Starting in 1968, state fisheries managers released the shrimp in several lakes of the Flathead watershed to enhance kokanee stocks; the shrimp moved downstream and reached Flathead Lake in 1981.

Instead of being a boon, though, Mysis competed with kokanee for their preferred food, zooplankton. The kokanee population collapsed. More importantly, younger lake trout feasted on shrimp, and the population soared. They ate nearly all of the remaining kokanee, as well as any other fish they could get their mouths around. Today, an estimated 1.6 million lake trout live in Flathead; more have since migrated and colonized most of the watershed.

Many of the remaining native fishes in Flathead Lake have dramatically declined, including bull trout, the top native predator. The Flathead watershed is the species’ regional stronghold, although it is found in cold streams and lakes from Montana to Oregon to the Yukon. As a fish, it is not especially flashy. Adults are olive-green with a creamy belly and light spots on their back and sides. (When they spawn, though, the green saturates almost to black, the belly to a smoldering ember orange.) But they share salmonids’ endurance. Some migrate to Flathead Lake from natal streams up to 130 miles away. There, they mature and grow before returning to their home streams to spawn; unlike Pacific salmon, they survive the journey, and may repeat it several times during their life.

Dams and logging hit bull trout hard, but lake trout were a new kind of threat, devouring young bull trout and outcompeting adults. The lake trout could also live 30-40 years to a bull trout’s 12-15, and spawn, as their name implies, in lakes.

By 1996, just 1,300 bull trout survived in Flathead Lake. Two years later, they were listed as threatened under the Endangered Species Act. Scientists now estimate that the population is slightly higher, with somewhere between 3,500 and 5,000 left.

Untangling Flathead Lake’s complex history of biological winners and losers is one thing. Fixing it is another, in part because the politics is as snarled as the ecology.

Two groups manage fisheries in the lake: Montana Fish, Wildlife and Parks oversees the lake’s northern half; the Confederated Salish and Kootenai Tribes Fisheries Program, the southern half. The Flathead watershed supports a $20 million fishery that both profit from, but the bull trout’s decline, along with the federal government’s determination to save it, has fractured a once-collaborative relationship. Both sides readily acknowledge this issue.

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  • Cathrine L. Walters

“It’s a battle over public sentiment,” says tribal biologist Barry Hansen, “and over who’s controlling the facts.”

“The nature of the situation at present is that we don’t talk,” says state biologist Mark Deleray.

The relationship wasn’t always like this. In 2000, the state and the tribes wrote a co-management recovery plan, which aimed to increase bull trout populations above “secure levels,” so the species would no longer be at high risk of extinction. The plan originally deemed bull trout secure if there were 300 redds—or the hollow a female fish scours out of a riverbed to lay her eggs in—among the Flathead watershed’s 31 spawning tributaries.

In the most recent survey, biologists counted 500 redds. The state believes that means bull trout are doing well enough to avoid drastic recovery measures. Tribal and federal biologists disagree. They argue that when the plan was written no one fully understood the complex biology, and so the definition of “secure” was arbitrary.

“It’s worthless,” says Hansen. “The parties were feeling politically pressured to come up with a number.”

As University of Montana biologist Fred Allendorf observed when the plan was released, the distribution of redds is as important as their numbers: A concentration of 500 redds in only one or two tributaries, or even an equitable distribution of them across many tributaries, could leave the species vulnerable to random events, such as mudslides or winter floods.

The most recent counts from 2012 bear out such concerns. In the Middle and North Forks of the Flathead River, biologists found that 55 percent of the tributaries supported 10 or fewer spawning bull trout females. Meanwhile, lake trout have invaded nine of 12 interconnected lakes between Flathead and Glacier National Park; in eight of them, bull trout are functionally extinct.

But you can’t bring back the bull trout without removing oodles of lake trout. Anglers now catch 70,000 or so each year, about 50,000 of those during semiannual fishing derbies called Mack Days (with a $10,000 first prize). But all that effort has yet to help bull trout. One reason might be that, since 1994, the state has prohibited anglers from keeping lake trout between 30 and 36 inches long, and allowed them to keep only one fish over 36 inches. Tribal biologists say this lets the largest and most voracious lake trout persist. That’s good for sport fishers, who are allowed to catch up to 100 lake trout per day, including the occasional behemoth, but bad for bull trout.

It is here that the state’s dual mandates—protecting a threatened native fish, and sustaining a multimillion-dollar recreational fishery built around that native fish’s bête noire—collide. Bonnie Ellis, a biologist at UM’s Flathead Lake Biological Station, says, “If (Fish, Wildlife and Parks) wants to protect the largest lake trout in the lake, while at the same time reduce the population, then those two aims are not very compatible.”

Last June, the tribes released a draft plan to reduce lake trout abundance in Flathead Lake by either 25, 50 or 75 percent over 50 years. This translates to removing 84,000-143,000 lake trout per year through a combination of derbies, bounties and two types of netting: trap nets, which are large box nets set on the lake bottom, and gill nets.

The plan was supposed to revive the co-management plan’s collaborative spirit, but the state pulled out of the process in March 2012, and then published a series of objections in the local newspaper after the plan was released. Biologists argue that gill-netting could indiscriminately harm both lake and bull trout. “Bycatch is a real concern,” says Vashro, who retired at the end of 2013.

The tribe counters that in Lake Pend Oreille, Swan Lake, Quartz Lake and Yellowstone Lake (see sidebar), gill-netting has successfully suppressed lake trout numbers. But Vashro points out that those lakes are smaller, so the results aren’t easily comparable. He has a larger concern, too: No matter how many lake trout are caught, those that remain will eat Mysis, which continue to thrive. “This is not the same lake as it was in 1980,” he says. “Until you understand that, you’re just treating symptoms.”

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  • Cathrine L. Walters

Ellis agrees that ridding the lake of Mysis is likely impossible, but she also believes that their numbers might be held in check by Flathead’s other species, such as lake whitefish, which eat the shrimp and are not known to harm bull trout. Still, eradicating lake trout is also likely impossible, and continuous long-term suppression would be necessary if managers intend to keep the species at bay.

The tribes are willing to do just that, says Tom McDonald, the manager of their fish and wildlife division. Throughout the history of the Bitterroot Salish, the Pend d’Oreille and the Kootenai peoples, bull trout and cutthroat were a reliable food source where other fish and game were unpredictable, especially during hard winters. They were another type of sustenance, too, as the tribes ceded swaths of territory to the United States with the signing of the Hellgate Treaty in 1855, and again when more land was taken in the early 20th century, during land allotment.

“These fish are of extreme cultural importance to us,” he says. “Letting them wink out on our watch wouldn’t be just ecologically bankrupt—it would be morally bankrupt.”

In September, the tribal council voted to reduce lake trout populations by 75 percent in 50 years. After the Bureau of Indian Affairs reviews the finalized plan, gill-netting in Flathead Lake could begin as early as this year. But whether it will take place on the entire lake, or just the tribes’ half, has yet to be resolved. For now, the state size limit also stands. And so this Solomonic exercise in fisheries management will continue, until someone sees fit to budge.

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  • CSKT

“Do you guys wanna keep it?” Capt. Rod asks.

The lake trout’s gills flare as it gasps for breath, but otherwise it doesn’t struggle. It is time for us to answer the question at the heart of the matter for it and its species: catch or release?

“Yeah, we’ll keep it,” one member of our party says. “Maybe we’ll cook it up later.”

“Okay,” Rod says, and he takes the trout from me and lowers it back into the lake and lets it go. (Perhaps he didn’t hear us?) The trout drifts away, floating on its back, its fins lolling in our wake.

I ask if the trout will be okay. “He had some kick, I’m sure he’ll be fine,” Rod says.

A few gulls land on the lake and get busy.

Rod watches for a few seconds, then makes his way back to the wheel. “I bet you hate that I released him,” he says to Vashro.

“Not a bit,” Vashro says. He grins inscrutably. “You know, I let most of the ones I catch go, too.”

This story originally appeared in the Feb. 3 issue of High Country News (

Location matters in the war on Lake Trout

Lake trout aren’t just found in low-elevation lakes with large recreational fisheries, like Montana’s Flathead Lake. For more than two decades, they have thrived in the crystalline, icy waters of Yellowstone Lake, in the heart of Yellowstone National Park.

Biologists believe someone introduced lake trout to Yellowstone Lake back in the 1980s. Since then, the population has exploded, while the Yellowstone cutthroat trout, a beautiful, small-bodied native, has declined by more than 90 percent. Lake trout both eat and compete with cutthroat trout, as they do with bull trout in the Flathead drainage.

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  • Cathrine L. Walters

The loss of cutthroats has rippled through the ecosystem. Unlike lake trout, which spend their entire lives in lakes, cutthroat return to their natal streams to spawn. There, a host of animals—from spiders to bald eagles to grizzly bears—depend in some way on their carcasses for food. Scientists are finding that when those animals can’t get trout, they’ll turn to other things. Arthur Middleton, a biologist at Yale, recently published a paper in the journal Proceedings of the Royal Society B showing that, in the absence of cutthroat, grizzly bears have started eating more elk calves. As a result, some elk populations have declined. “That a change in the trout fishery can reach to elk migration is striking,” Middleton says. “It shows how the broader effects can be felt far outside the park.”

This helps explain Yellowstone’s increasingly aggressive drive to eradicate lake trout. Unlike at Flathead Lake, where there is an entrenched lake trout recreational fishery and multiple managers, Yellowstone Lake is overseen solely by the National Park Service, which has a mission to preserve native species. Park biologists have had broad public support to deploy increasingly sophisticated methods, including using experienced gill-netting crews from the Great Lakes to sweep up lake trout.

In the first years, gill-netters caught 25,000 to 50,000 lake trout each summer; the catch rose to around 100,000 by the mid-2000s. As funding has increased—to over $1 million a year from both private and public sources—so, too, has fishing; gill-netters now remove between 200,000 and 300,000 lake trout per year. Although the agency has gotten some pushback from lake trout-loving fishers, most angling groups support the effort, says Dave Hallac, division chief of the Yellowstone Center for Resources at the park.

The exact number of remaining lake trout is unknown, but Hallac guesses that it is in the hundreds of thousands, and that gill-netting will need to go on for years. But there are promising signs that the population is declining. In the last two years, gill-netters have caught fewer lake trout, and an independent monitoring program has found juvenile cutthroat trout in Yellowstone Lake for the first time in years. “It’s too early to claim success just yet,” Hallac says, “but we’re definitely on the right track.”

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