Kill it, then call it in. That is Montana Fish, Wildlife and Parks' message to anglers after non-native brown trout turned up at two locations in the Flathead drainage - the first confirmed detections since a lone fish surfaced in the river last summer.
An angler photographed the first at Ashley Lake in February, unsure what he had caught, and released it. A second was later landed in the same lake and given to biologists. A third came from Church Slough in late July. Both waters connect to the Flathead River, which is what worries the agency.
"This is a big deal," FWP fisheries biologist Kenny Breidinger told the Daily Inter Lake. "We take this one very seriously. There is a lot of potential for harm from brown trout in the drainage."
The upper Flathead has largely escaped brown trout, and it still holds Westslope cutthroat and federally threatened bull trout.
"In Ashley Lake and Church Slough, brown trout will compete for resources with and prey upon other sportfish," Breidinger said in an agency release. "More concerning, both waterbodies provide a source for brown trout to spread throughout the Flathead Drainage. This would have substantial negative impacts on the Flathead fisheries."
Ashley Lake's only outlet is dammed, so the trout almost certainly did not swim there. Biologists will read trace elements in the recovered fish's otoliths - ear bones that record the chemistry of the water a fish grew up in - to work out where they were born.
"If you know of anybody who's doing this or have any information that may be helpful in tracking down some of these criminals, it would be great to turn that into our law enforcement office and game warden," he told KPAX.
Jim Vashro, who managed fisheries for FWP Region 1 before retiring, has watched the same pattern play out in the Thompson and Kootenai rivers.
"Unfortunately, this latest detection isn't the only case where someone has moved brown trout around," Vashro told the Flathead Beacon. "At this point, any detection of brown trout in the Flathead River has got to be some sort of bucket biology."
Regional fisheries manager Mike Hensler put the priority plainly when the 2025 fish appeared: "Protecting our native trout populations is a priority. Brown trout pose a threat to native species in the Flathead drainage, and we need the public's help to manage this invasive species."
The contradiction is not lost on anglers. Below SKQ Dam, brown trout are a legitimate and popular fishery, contained by the impoundment. Above it, the same species is treated as a threat to be removed on sight.
Elsewhere in the state it has been a bad season for illegal stocking: pike near the Madison River, bass in a Livingston lagoon, and pike dumped into Pine Grove Pond, a stocked kids' fishery near Kalispell with no connection to other water. FWP has put up a reward of as much as $3,500.
"This is an extremely disappointing and damaging act," Hensler said. "Pine Grove Pond was built and managed as a place for kids and families to learn to fish and enjoy catching trout. Introducing pike could ruin that experience for everyone."
One practical note for anyone fishing the drainage: a lake-dwelling brown may not show the classic golden flanks and haloed spots at all. It can look bright silver with a dark green back and heavy black spotting. Report anything you are unsure about to FWP Region 1 on 406-752-5501.
