Keila Szpaller

(Daily Montanan) Bull trout spawning sites in the Swan Lake basin hit their lowest count in 42 years in 2023, according to data from Montana Fish, Wildlife and Parks.

In a news release this week, FWP announced it wants to cut down on lake trout in Swan Lake to help 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,” FWP said.

As such, FWP is seeking public comment on a gillnetting plan in Swan Lake. Already, conservation advocates are lauding the renewed attention to the lake in the Swan Valley.

Bull trout were listed as “threatened” under the Endangered Species Act in 1998, FWP said.

Their decline in Swan Lake is mainly due to lake trout, which FWP described as “highly effective predators.” They increase competition for food and also prey on juvenile bull trout.

According to FWP, lake trout were either illegally introduced to Swan Lake or they potentially migrated through a fish ladder that has since been closed.

Lake trout were discovered in Swan Lake in 1998, and since then, bull trout have shown “considerable decline,” according to FWP’s draft environmental assessment.

A count of bull trout spawning sites, or “redds,” in Swan Lake tributaries dropped to 135 from more than 700 in 2008 and more than 800 in 1998, according to the draft EA. It said redd counts provide “the best metric for examining trends in adult bull trout numbers over time.”

Arlene Montgomery, with Friends of the Wild Swan, said FWP previously used gillnets to remove lake trout but stopped that work a number of years ago.

“I have been urging them for several years to get back to doing this again because we’re going to lose bull trout in the Swan. It might already be too late. I hope not,” Montgomery said.

She said she has not reviewed the plan in depth, but she believes FWP learned a lot about the best ways to use gillnets in the past — for example, so as not to also catch bull trout.

Regardless, she said something needs to be done to suppress lake trout, which also have infested Holland Lake and Lindbergh Lake.

“They’re through the whole system, and it’s really a travesty,” she said of the Swan Valley.

The Montana Fish and Wildlife Commission approved FWP’s proposal in February.

FWP said lake trout suppression efforts have benefited native fish conservation in other lakes, 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,” FWP said.