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Montana Effort To Restore Native Fish In Alpine Flathead Lakes Nears Finish Line
Posted on Friday, August 11, 2017 (PST)

An ambitious, long-term effort to restore native fisheries in alpine lakes above Montana’s South Fork Flathead River drainage — a major tributary in the Columbia River headwaters — is coming to a successful conclusion this fall.


That wasn’t necessarily the public view when the project was pitched more than 10 years ago. The proposed use of Rotenone toxin to purge non-native rainbows or cutthroat-rainbow hybrids, and other aspects of the project, were met with suspicions and concerns.


“There were a myriad of concerns that we were dealing with,” said Matt Boyer, science program manager for Montana Fish, Wildlife and Parks in Kalispell. “We were proposing a native fish restoration project on waters that were a really popular sport fishery. Not only that, we were doing it with Rotenone … We had to, right out of the chute, start an education program to sort of teach people what we were proposing. Some of it was to address the concern that we were just going to destroy the fishery.”


While Rotenone has been used for decades in scattered efforts that were deemed successful, it hadn’t been applied as a major tool in a landscape-scale conservation project targeting 19 alpine lakes. Seven of those were treated with genetic swamping, basically overwhelming the non-native and hybrid fish that were present. Rotenone was used where swamping approach was not expected to succeed. And there were valid questions about how the chemical would impact insects and amphibians, Boyer said.


That prompted in-house research involving field surveys measuring the occurrence of amphibians and insects in and around lakes that were proposed for treatment. The project was rolled out with an adaptive management strategy where the lessons learned from initial target lakes could be applied to the remaining lakes.


It was a conservative, lake-by-lake approach, which was a critical part of its eventual acceptance and progression, Boyer said, adding that scientifically, it was the best approach as well.


Had aquatic insects been decimated with lasting effects, for instance, the work would be considered entirely counterproductive.


“That would defeat the purpose of the work. We wanted to build a track record of successes rebuilding these native fisheries,” Boyer said.


The state’s amphibian work has since become a topic of its own with publication in the North American Journal of Fisheries.


“We didn’t find any affect or change on a lake after Rotenone treatment,” Boyer said. That is attributed partly to the timing of the fall treatments, along with repopulation of lakes from surrounding habitat, and safeguard practices, such as using a chemical to neutralize the effects of Rotenone, which is also degraded by sunlight.


Boyer and his team also had to demonstrate the recovery of the fisheries after being planted with genetically pure west slope cutthroat trout derived from the avant garde Sekokini Springs conservation hatchery located near the town of Hungry Horse and Hungry Horse Dam at the foot of the South Fork Flathead drainage.


For this project and many others, Boyer said, it has been important to dispel the wide held belief that “a trout is a trout.” Extensive research in the Columbia Basin involving salmon have shown that hatchery fish lack the survival and reproductive instincts that wild fish have. Similar findings apply to rainbow trout raised from a genetic brood stock, compared to the wild fish raised at Sekokini Springs that were derived from South Fork drainages. Fish are cycled through the hatchery with the intent that “we have as minimal a fingerprint on these fish as possible,” Boyer said.


The approach at Sekokini Springs, which has been gradually established and developed during the general timeline of the alpine lakes work, has received lots of attention from far and wide. “Using local sources of trout, instead of a general brood stock, in many cases can be a smart way to do things, Boyer said.”


As for re-establishing angling fisheries — one of the main goals of the project — there has been great success, as measured by Fish, Wildlife and Parks and anglers who frequent the lakes.


“It varies some from lake-to-lake, depending on how much nutrients are present, but generally they have been restored within two to three years, with catch rates and size distribution of fish that we saw prior to the project.”


Because the work was staggered over a decade, there has been ample alpine lake angling opportunities in the project area throughout.


Economically, Boyer contends the project has been highly cost effective, with a price a tag of about $5 million from the Bonneville Power Administration’s Fish and Wildlife Mitigation Fund.


“The goal is to create self-sustaining fisheries” that do not need to be augmented with fish plants as much as before, Boyer said. “All these lakes have spawning habitat. The intent is that we will be able to back off the stocking.”


The work has caught the attention of fishery managers elsewhere. Glacier National Park is developing a Fisheries Management Plan with guidance from the alpine lakes project. Boyer said the plan is being developed in a way that would allow the use of Rotenone or other piscicides in the park. Nearly all of the lakes on Glacier’s western flank have been invaded by non-native lake trout with adverse impacts on native species, such as bull trout.


Boyer emphasized that Glacier’s fisheries plan will be developed through an entirely new and separate public involvement and environmental review process.


MFWP is also collaborating with the Confederated Salish-Kootenai Tribes for conservation work on the Flathead Reservation, and Boyer has been working with Parks Canada and the provinces of Alberta and British Columbia.


The final leg of the project will involve Rotenone treatment of the largest lake in the project area, 148-acre Sunburst Lake, which will be carried out Sept. 3-9 with the help of personnel from the Alberta provincial government and Parks Canada.


Because the work has been carried out on lakes inside wilderness boundaries, there have been logistical challenges. The Sunburst Lake crew will hike in, and a helicopter will be used for transporting equipment to the lake, which requires specific approval from the U.S. Forest Service.


Boyer is proud it has been a landscape-scale project, rather than a costly, ongoing piece-meal approach. “This isn’t suppression,” he said. “It’s an approach where you can accomplish conservation over a large landscape scale, with big benefits for fisheries.”


Also see:


-- CBB, Dec. 18, 2015, “Isolated Rearing Facility For Native Fish Key Component In Montana Effort To Reduce Hybridization”


-- CBB, Dec. 18, 2015, “Montana’s South Fork Flathead Cutthroat Conservation Project – Purging Non-Native Fish”


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