Big Hole River Update

Photo: Spend A Day Touring, LLC/Flickr

The Big Hole River, in southwest Montana, has been at the forefront of conservation efforts for the past few years due to its rapidly-declining trout population. Montana Fish, Wildlife & Parks (MFWP), scientists from Montana State University, and concerned guides and outfitters have worked together to study the Big Hole and offer potential solutions for this storied fishery.

MFWP has just released the results of their 2024 sampling efforts throughout the upper Missouri River Basin—which includes the Ruby, Big Hole, Beaverhead, and Jefferson Rivers. While there’s some positive data, many stakeholders in the area are calling for more action on behalf of the region’s trout populations.

“An overwhelming majority of trout from rivers in the upper Missouri River Basin are healthy,” MFWP said in a press release.

Extensive fish health sampling took place in the Big Hole, Ruby, and Beaverhead Rivers throughout 2024. This included fish tagging and creel surveys. During this sampling, which took place in spring and fall, less than one percent of fish showed signs of infection. Of the nearly 5,000 juvenile fish (not old enough to reproduce) observed, none showed any signs of infection.

“It’s encouraging that almost all fish in last year’s sampling efforts in the basin appeared healthy,” said Mike Duncan, FWP’s fisheries program manager in Region 3. “We’ll continue to monitor trout health closely in 2025.”

Brown trout redds also increased in the Big Hole River. MFWP counted 156 redds near Melrose, up from 108 redds counted in 2023.

Tagging trout enables the MFWP to track fish movement throughout the river, and paints a picture of fish mortality from external factors, as well. MFWP tagged nearly 12,000 trout throughout the upper Missouri River Basin, and roughly 1,300 of those trout have been caught and reported by anglers.

“Anglers who report catching tagged fish are helping biologists and MSU study trout population declines in parts of the basin,” MFWP said. “Fish managers can use angling and annual sampling as ways to measure how environmental factors like flows and water temperatures are affecting fish populations by species, age class, waterbody and time of year.”

But not everyone is so bullish about the state of these watersheds. Flows, water temperature, and water quality are still issues that haven’t been adequately addressed, according to Save Wild Trout.

Save Wild Trout is a coalition of guides, outfitters, and anglers in southwest Montana. Wade Fellin is a member of Save Wild Trout and owner of the Big Hole Lodge. Fellin made this statement to MidCurrent:

“Save Wild Trout appreciates Montana FWP’s continued examination of why trout populations on the Big Hole, the lower Beaverhead, and Ruby have collapsed to historic lows. We look forward to further results from the other studies in progress, including identification of the disease afflicting trout earlier in the season than the late season timing of this sample set. No one wants to see or catch diseased and dying wild trout, so finding fewer than anticipated is good news, but it should not divert attention from the bigger issue at this critical juncture: FWP’s population studies show we have unsustainable declines in wild trout fisheries in SW Montana.

“‘Best available science on the rivers supporting SW Montana’s wild trout shows deteriorating and unsuitable habitat for aquatic life. These unhealthy conditions point to the need for action by Montana’s leadership and other agencies, including DEQ and DNRC, to help preserve one of the last wild trout populations in the Lower 48. Far too often river monitoring is showing water quality conditions harmful for wild trout, including excessive nutrient pollution, extreme water temperatures, and low dissolved oxygen––all of which continue to be unaddressed.’ – Wade Fellin, Save Wild Trout.

“Half a decade of water quality data from the Big Hole River Foundation (BHRF) and preliminary data from Save Wild Trout indicate we’re witnessing the cumulative impacts of chronic strain on fish health due to poor environmental conditions, high water temperatures, low dissolved oxygen levels, and unhealthy nutrient pollution levels. These factors result in physiological stress in the fish and bug life by negatively impacting respiration, reproduction, and growth while increasing susceptibility to pathogens.”