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In 2007, after four years of environmental review, FWP began applying a toxicant called rotenone to remote mountain lakes in the South Fork drainage to kill all of the nonnative hybrid fish that thrive there.
"At that time," recalls FWP Fisheries Mitigation Coordinator Joel Tohtz, "there was a lot of concern—legitimate concern from everybody, including internally on our staffs—about what we were doing, and all of things you have to watch out for, the pre-work that goes into this, all the monitoring of levels of toxicants and making sure they're doing what you think they are."
The nonnative fish were largely introduced into the lakes—many of which were historically fishless—by the government and the public between the 1920s and 1960s. Even before the '20s, says FWP Regional Fisheries Manager Jim Vashro, people were "amazingly determined" to stock these lakes with fish.photos by Cathrine L. Walters
"I read one report on stocking Lake Mary Ronan," says Vashro, "and the fish came in on the train and it took them three days by wagon—this was in the 1880s—to get the fish up and planted."
All of the lakes lie above the Hungry Horse Reservoir, which separates the South Fork drainage from the rest of the Flathead River system. The reservoir, and the Hungry Horse Dam that created it, are central to the restoration effort, partly because it means that the Bonneville Power Administration, charged with mitigating the effects of northwest hydropower facilities on fisheries thanks to the Northwest Power Act of 1980, is paying for it. Last year the dam's mitigation budget was about $1.8 million, about $500,000 of which went toward poisoning lakes in the South Fork to make way for the wild cutthroats. The entire 10-year Westslope Cutthroat Trout Conservation Project is expected to cost more than $2 million.
FWP began the project in 2007 by treating Black and Blackfoot lakes. It treated Lower Big Hawk Lake in 2008, and Clayton and Margaret lakes in 2009. All are on Flathead National Forest land east of the Hungry Horse Reservoir and south of Glacier National Park. The remaining 16 lakes are scheduled to be poisoned in the coming years.
The project still makes some fishermen scratch their heads. They were used to catching big, beautiful rainbows and Yellowstone cutthroats, and never seemed to mind that those species weren't there—nor any other fish species—100 years ago.
After Staigmiller removes a fish's head, spleen and kidneys, he passes the rest of the body on to fellow Fish Health Specialist Marc Terrazas. With his tiny forceps, Terrazas carefully pulls out the fish's testes, which look like a gooey white string. He jokes about its resemblance to an earthworm.
Terrazas then passes the testes to another biologist, Mark Kornick of the Flathead Lake Salmon Hatchery, who blots blood off the testes with a paper towel. Kornick then dices the testes into a milky mush.
Meanwhile, a few hundred feet away at the covered end of a fish hatchery raceway, three more FWP biologists, wearing waders and rubber gloves, stand in the water next to a tub of motionless cutthroats. They're anesthetized four-year-old females from the hatchery's brood stock, and the biologists pick them up out of the water one by one and squeeze and massage the fish's sides, and out squirts a stream of florescent orange eggs into a stainless steel bowl. FWP Fish Culturist Paul Suek explains that each fish yields, on average, about 1,100 eggs.
Plastic containers of freshly squeezed fish eggs are taken back to the garage, where they await their union with the mush of invisibly teeming sperm.
FWP held its annual informational meeting on the Westslope Cutthroat Conservation Project in late May at its office in Kalispell. With the rotenone treatment of Wildcat Lake scheduled for the fall, opponents of the plan were expected to show up. But none did. Agency staffers outnumbered members of the public, who barely outnumbered the two journalists in attendance.
"I think this meeting is a good sign," Vashro said. "This has been a contentious project. I mean, taking chemicals into the Bob Marshall Wilderness is no small issue, and it took four years just to get through the environmental reviews, and some of those earlier meetings were well attended and very passionate. And so I think this is an indication that the work Matt and his crew are doing is dealing with a lot of those concerns and moving ahead."
Vashro was referring to Matt Boyer, the project's lead biologist who had just completed a presentation on its progress. He detailed how the agency monitors the success of rotenone treatments.
"We're not just thinking about restoring fisheries, but also about the things that sustain these fisheries, and that's down to the plankton, the insects and amphibians," Boyer said. "So when we're managing for the persistence of native westslope cutthroat trout, we're trying to think long-term, trying to keep intact the ecosystems and evolutionary processes that allow these things to exist."
FWP calculates the volume of the lake in order to apply the correct amount of rotenone needed to achieve a concentration of one part per million. "We're lucky that trout are pretty wimpy to this stuff," Boyer said. Then the agency flies an air tanker—the same kind used for crop dusting or dropping fire retardant—or uses a boat to apply the chemical. It also sets up "drip stations" to access lake tributaries. The agency treats the entire fishery up to a barrier waterfall.
Amphibians—including the Columbia spotted frog, western toad, long-toed salamander and tailed frog—largely avoid the rotenone, Boyer said, because they're typically in their terrestrial stage in the fall when the piscicide is applied. But invertebrate numbers dip.
Boyer displayed a slide showing the number of invertebrate taxa—insects like mayflies, midges and beetles—in Black and Blackfoot lakes before and after treatment. In Black Lake in 2007, before treatment, biologists counted 27 taxa. After treatment, in 2008, the number dropped to 19. But they had rebounded by last year when biologists counted 23. Blackfoot Lake saw a similar dip, but the number of taxa found last year, 36, actually exceeded the pre-treatment count of 34. Boyer said it takes a few months, roughly, depending on the size of the lake, for the rotenone to break down and become non-detectable.