FWP Seeks Input on Proposed Lake Trout Removal Project in Swan Lake

With the aim of improving bull trout and kokanee salmon populations, the proposed gillnetting program to suppress invasive lake trout has received broad support

By Tristan Scott
A bull trout in the Kootenai River system, which sees an annual migration of bull trout from Lake Koocanusa. Beacon file photo

Fisheries managers with Montana Fish, Wildlife and Parks (FWP) are seeking public input on a proposal to reduce the lake trout population in Swan Lake to improve bull trout and kokanee salmon populations.

Once home to a large, stable bull trout population and popular kokanee fishery, Swan Lake has seen significant declines in abundance of both species while lake trout numbers have increased considerably. Bull trout spawning nest counts in 2023 revealed the lowest number on record in the Swan.

“With a duty to conserve native species, FWP has introduced a proposal to remove nonnative lake trout through gillnetting efforts until lake trout numbers are sufficiently low enough to improve bull trout and kokanee salmon numbers,” according to an agency press release.

FWP outlined its proposed plan with a draft environmental assessment that is available to review online at https://fwp.mt.gov/news/public-notices. FWP is seeking public comment on the proposal through June 28 at 5 p.m.

Additionally, FWP is hosting two public information meetings to discuss the proposed project during the comment period. The first meeting is June 4 at 6 p.m. at the FWP office in Kalispell, located at 490 N. Meridian. The second meeting is June 11 at 6 p.m. at the Swan Lake Chamber and Community Club, located at 22778 Montana Highway 83.

The public is invited to ask questions and learn more about the proposal.

Bull trout were listed as threatened under the Endangered Species Act in 1998. The decline of native bull trout in Swan Lake is largely attributed to the expansion of lake trout, which were either illegally introduced or potentially migrated through a now-closed fish ladder. Lake trout are highly effective predators, and their presence has led to increased competition for food and habitat resources. Additionally, lake trout prey on juvenile bull trout, further reducing their population. Predation and competition have severely impacted the bull trout population, necessitating conservation efforts by FWP.

A large migratory bull trout captured in Boulder Creek in the St. Mary River drainage of Glacier National Park. Photo courtesy of Jim Mogen, U.S. Fish and Wildlife Service

Lake trout suppression efforts have benefited native fish conservation efforts in other lakes across the West, including Yellowstone Lake in Wyoming and Lake Pend Oreille in Idaho.

All lake trout netted during the project would be killed and those that are salvageable and of suitable size for consumption would be donated to food banks or other organizations.

Comments can be submitted via email to fisheries biologist Leo Rosenthal at [email protected] or regional fisheries manager Mike Hensler at [email protected], or via mail to Swan Lake EA, 490 N. Meridian, Kalispell, MT 59901.

The Montana Fish and Wildlife Commission approved FWP’s proposed management action to remove lake trout from Swan Lake at its February meeting.

The commissioners passed the gillnetting initiative after hearing support from a diverse range of stakeholders, including representatives of the Montana Outfitters and Guides Association (MOGA), the Fishing Outfitters Association of Montana (FOAM) and Trout Unlimited. Representatives from all three groups recognized the ecological value of restoring native fisheries, as well as the recreational value of improving kokanee populations.

FWP conducted a similar lake trout suppression effort on Swan Lake between 2009 and 2016, with mixed results. FWP and its partners conducted that eight-year experimental lake trout removal project on Swan Lake to determine whether suppression tactics such as gillnetting are effective at reducing lake trout abundance and improving native bull trout and kokanee salmon populations. However, lake trout populations rebounded once the project was concluded on Swan Lake, while the abundance of native species resumed a negative trajectory.

“Since 2016, Swan Lake bull trout and kokanee abundances have declined while lake trout has increased considerably,” according to FWP’s proposal. “Bull trout redd (spawning nests) counts in 2023 revealed the lowest number on record.”

Spawning kokanee salmon at Lake Mary Ronan. Beacon file photo

As required by the Montana Environmental Policy Act (MEPA), FWP will complete scoping of the proposed project before any management action.

Under the plan, fisheries managers will ramp up monitoring efforts of lake trout in Swan Lake this year before implementing the gillnetting strategy in 2025, resuming an invasive species suppression campaign that has proven only partially effective in the past, but which has been refined in the intervening decade.

Additional lake trout population assessment and modeling since 2016 has shown that increased gillnetting efforts to remove lake trout could positively influence bull trout abundance, according to FWP.

“With no action bull trout numbers are expected to continue to decline while lake trout increase,” according to the agency’s proposal to commissioners.

According to FWP’s monitoring data, which spans more than 40 years, declining redd numbers were documented at 48% of FWP’s monitoring sites last fall. They were shown to be increasing in 12% of the sites and registered as stable in 40%.

[email protected]