State orders catch-kill-report rule for brown trout in Flathead Drainage

State fisheries officials are taking the first steps toward controlling the recent infiltration of invasive trout into the Upper Flathead Drainage.

The Montana Fish and Wildlife Commission unanimously approved an emergency catch-kill-report regulation for brown trout in the Flathead Drainage upstream of the SKQ Dam on Oct. 14. 

Montana Fish, Wildlife and Parks has received scattered reports over the past two years of non-native trout in local waterbodies, including two confirmed brown trout captures in Ashley Lake. Officials could not verify several other reports of brown trout in the Flathead River and Church Slough. Still, they described the sightings as "likely legitimate" in a request to the governor-appointed members of the Fish and Wildlife Commission.

These brown trout are the result of illegal introductions and pose a real threat to sport and native fish throughout the drainage," the document stated. 

A prized quarry for fly fishermen, brown trout are stocked in many Montana waterbodies. But fisheries biologists consider the cold-loving salmonids invasive in the upper Flathead Drainage because they prey upon and compete with native fish species, including vulnerable populations of bull trout and westslope cutthroat trout. 

"We are known as an intact cutthroat trout fishery, and we're very proud of that. We want to keep that stronghold here, and this [regulation] will help us do that," Flathead Valley fishing outfitter Mark Fuller told the commission during a public comment period. 

The Confederated Salish and Kootenai Tribes, Montana Trout Unlimited, the Fishing Outfitters Association of Montana, and Flathead Wildlife also voiced support for the rule, which will take effect with the 2027 fishing regulations. 

The measure requires anglers to immediately kill and retain any brown trout they catch upstream of the SKQ Dam, including in Flathead Lake. Anglers must report the catch to Montana Fish, Wildlife and Parks within 24 hours and either drop the fish off at a regional office or arrange to transfer them to the state wildlife agency within 10 days of capture. 

Fish should be delivered whole, though they may be frozen before drop-off. Fisheries biologists will return edible portions of the fish upon request. 

Fisheries biologists will analyze the ear bones of the submitted brown trout carcasses for trace elements, then map them to specific streams to determine where a fish was born. That information, along with observations on the trout’s reproductive status, will help officials determine whether the local brown trout population has become established enough to reproduce.    

"In any situation like this, all biological information is relevant," Fisheries Division Administrator Adam Strainer said. 

"I think the most important critical piece here is contacting Montana Fish, Wildlife and Parks," he added. 

The Confederated Salish and Kootenai Tribes intend to implement an identical regulation on the tribally managed portions of Flathead Lake, according to the regulation request. 

Reporter Hailey Smalley can be reached at 406-758-4433 or [email protected].