Single brown trout raises flags on Kootenai River

Single brown trout raises flags on Kootenai River

News Type: State Source: Missoulian
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A single brown trout caught by an angler in late February on the Kootenai River between Libby Dam and Kootenai Falls is sounding alarm bells for people who enjoy the trophy, world-class rainbow trout fishery.

“If brown trout become established and persist, it is quite likely this long-lived voracious predator will negatively impact both rainbow and bull trout populations, especially at fry and fingerling stages,” noted Mike Hensler, a Montana Fish, Wildlife & Parks fisheries biologist.

“We really want to protect not just that section of river, but it is amplified there. There’s no reason for brown trout in the Kootenai drainage,” Hensler said.

Every brown trout caught on the Kootenai River between Libby Dam and Kootenai Falls would need to be killed immediately, kept and reported to authorities within 24 hours under a proposal being considered this week by the Montana Fish and Wildlife Commission. Staff at FWP are proposing the regulation change to prevent brown trout from establishing in the river and damaging rainbow and bull trout populations.

Hensler said the state record rainbow trout came from that section of river, where it’s not uncommon to catch a 10-pound rainbow. Bull trout, which also inhabit that stretch, are listed as threatened under the Endangered Species Act.

While brown trout are prized by anglers in some streams, they’re not native to Montana. They were introduced in the Madison River in 1889, and today are found throughout most of the state.

Hensler said the brown trout population already is established in the lower Kootenai River, but none had been able to make it upstream of the waterfall. He’s not sure how this one managed to swim up the 300-foot elevation gain in the Kootenai Falls area.

“As we see it right now, there are only two ways this brown trout could have gotten there,” Hensler said. “Either it came upstream over Kootenai Falls; we did have one bull trout — 28 inches — that we think did that. It was tagged so we knew where it had been. But that’s highly unlikely for the brown.

“The other possibility is that somebody brought it in and dropped there, or there are brown trout getting established somewhere up there — in Loon Lake or Fisher River.”

FWP protocol calls for biologists to begin assessing whether a brown trout population has been established or if this was an unauthorized introduction. Hensler said FWP has spent the last 20 years doing population estimates in that stretch of river, and despite handling “hundreds of thousands” of fish, they’ve never caught a brown trout.

They plan to electro-shock the fish in the fall to survey for brown trout. Hensler said they can’t do it any earlier this year because the rainbow trout are spawning, and electro-shocking at this time would put too much stress on them. Once they’re shocked, the fish are drawn into a net where biologists get additional information, like measurements, and some are tagged.

“We’ll handle over 1,000 fish in two or three nights,” Hensler said. “If we don’t find them, it doesn’t mean they’re not there, but we are trying hard to find them.”

David Brooks, executive director of Montana Trout Unlimited, said on Monday that he wasn’t aware of the proposal, so he didn’t want to comment on it specifically. However, he said his organization generally is supportive of FWP’s efforts to enforce laws regarding the illegal introduction of fish.

He noted that FWP undertook a similar effort after two non-native walleye were found in Swan Lake in 2015. Biologists traced their origin to Lake Helena by looking at their inner ear bones, which hold unique geochemical tracers from the water chemistry where the fish swims. The intricacies of the water chemistry can be used to map the entire life history of a fish.

“In general, we have been supportive of the do-no-harm tactics, and expect that this will be a short-term thing to find out if they have browns in there and how to manage them if they do,” Brooks said.

Tim Linehan, owner of Linehan Outfitting Co., spends about 99 percent of his guiding time on the upper and lower stretches of the Kootenai River. He’d heard about the brown trout, and said that while guides have mixed feelings about killing any trout, he supports what FWP proposes.

“In this case I trust FWP implicitly. They do a good job managing our reservoir, and if they think this is the action that’s needed, I support that,” he said. “But it’s tricky; ask 12 Kootenai River guides about it in a room, and I bet six, seven or eight would say to leave them, that they fill a niche.”

The fishing season on that stretch of river is closed until June 1. Hensler hopes that the Fish and Wildlife Commission will agree with his recommendation during its meeting Thursday, and anglers will kill and keep every brown trout they catch.

Brown trout are easily identified by their brownish color, while rainbows are silver colored with a rose-colored gill plate and a rainbow-like stripe along its sides.

The Fish and Wildlife Commission meeting begins at 8:30 a.m. April 19 at its headquarters in Helena. Video display of the meeting can be watched at its regional offices, and comments will be accepted on the proposal. Audio of the meeting also is available via on a listen-only basis.