Big Hole Bounceback
A brighter future for an iconic Montana river.
Last spring, my first day back on the water was a nine-mile April float on the Big Hole. I was tagging along with the crew from the Madison River Fishing Company, a shop and outfitter in Ennis, to film for the day, and we put in at Notch Bottom, a dirt boat-launch on the lower stretch of the river. Despite reports of declining trout numbers on the Big Hole, we had high hopes, and this early in the season whatever fish were in there had seen very little pressure. The river chuckled along, not giving up its secrets as we launched the boats and drifted down the curling blue ribbon.
A year ago, the Big Hole was in trouble. FWP fish counts in 2023 showed all-time low populations of brown and rainbow trout in the fishery, with fewer than 500 trout per mile in a river that once contained around 1,500 (although anecdotally, the river still fished quite well that year). The Ruby and Beaverhead rivers were in a similar predicament, with trout numbers plummeting over the past eight years. “It was as bad as it’s ever been since we started collecting data,” says Jim Olsen, regional biologist for FWP. There are many theories for why—low flows, high temperatures, nutrient runoff, disease—but no satisfactory explanations so far. But after nearly a decade of decline, trout on the Big Hole may be mounting a comeback.
After months of bitter cold and iced-up boat ramps, to catch any fish was a thrill, but the browns that our crew netted were handsome fish, as large as 20 inches and glistening bronze, blue, and golden yellow in the sunshine.
Fishing is an exercise in hope, and all of us floating down the Big Hole that day were hoping the river was swimming with big, hungry trout. It took a couple hours, but eventually we found ’em. Rods were snapping down left and right, with whoops sounding from almost every boat as healthy browns slurped our favorite flies and lucky streamers. I was just there to film, so I sat back and kept my camera leveled at the action. After months of bitter cold and iced-up boat ramps, to catch any fish was a thrill, but the browns that our crew netted were handsome fish, as large as 20 inches and glistening bronze, blue, and golden yellow in the sunshine. Around one o’clock, we pulled over on a small island and grilled brats from Deemo’s, tossing scraps to Murray the boat dog and lolling about on the greening grass.
A month after our float, FWP released their latest fish count from the Big Hole, and the results were promising. Though trout populations were still a far cry from historic averages, both brown and rainbow trout numbers crept back up, from an average of 331 brown trout per mile to 570; and 302 rainbows per mile to 361. Experts like Olsen say that an average water year, after several low-water years, helped the numbers rise. Many of the fish that he and his team counted were two-year-olds, which indicated a good recruitment year for young fish.
“It wasn’t a banner year, but it’d been several years since we had a decent year,” Olsen says. “It almost doubled the fish numbers that we saw.”
FWP also counted far fewer “zombie trout” in 2024, a recent phenomenon on the Big Hole that inspired fear from anglers and conservationists alike who caught or studied trout covered in cauliflower-like lesions or blinded by a fungal disease.
But despite headlines proclaiming a comeback in 2024 and Governor Gianforte visiting Wise River in June to celebrate the Big Hole’s rising trout counts, a recovery is far from guaranteed. 2024 was a year of drought, with a near-record-low snowpack across much of Montana, and FWP closed the Big Hole for much of August due to high temperatures and low flows. These conditions don’t bode well for 2025, but Olsen said there’s reason to be hopeful.
According to biologists, water levels are the main determinant of fish survival rates, but that doesn’t fully explain what’s happening on the Big Hole.
“When we have a really good recruitment year like 2024, it boosts the fishery for quite some time, because once the fish get above the juvenile stage, their survival rates are much higher,” Olsen says.
Though he hates to speculate, Olsen expects the Big Hole trout population will remain about the same as it was last year, with high survival rates of those two-year-old fish but a small age class of one- and two-year-olds who couldn’t survive 2024’s high temps and low flows. According to Olsen, water levels are the main determinant of fish survival rates, but that doesn’t fully explain what’s happening on the Big Hole. Die-offs began there during average water years, and other freestone rivers around Montana haven’t seen the same trends (except for the upper Clark Fork, which has also seen historic die-offs in the past decade). To get to the bottom of the Big Hole’s problems, FWP is conducting an intensive three-year study on adult and juvenile trout mortality, as well as a recreational-use study, which will also examine the Beaverhead, Ruby, and Madison rivers. Olsen hopes that it will help the state determine long-term solutions to sustain these fisheries.
“It’s been a very long time since we’ve dove in and taken this close of a look at our wild fisheries in this part of the state, so I’m really looking forward to all the things that are going to come out of these studies,” Olsen says.
If FWP concludes that available water is the culprit, they’ll determine how much water the fishery needs and how often it needs it to remain viable. If, on the other hand, they find disease to be the main problem, Olsen said that coming up with solutions will be more difficult. But there’s only so much FWP can do on its own. The agency’s jurisdiction is limited to managing angling impacts and the biological health of trout, and if a solution requires action like regulating the water rights of ranchers and residents living along the Big Hole River, it will take teamwork.
“This needs to be a collective effort,” says Jayson O’Neill, with the local nonprofit Save Wild Trout. “It can’t just be FWP in their box. It can’t just be the Department of Environmental Quality and the Department of Natural Resources and Conservation in their boxes.”
If temperatures remain high and the snowpack declines in the long run, best practices for anglers will become even more important.
FWP’s study won’t conclude until 2027, and in the meantime, other groups like Save Wild Trout are doing what they can to sustain the Big Hole. They and the Big Hole River Foundation (BHRF) are both conducting their own studies to get to the bottom of the river’s murky issues. BHRF has been collecting data on the Big Hole for four years, and the organization has found relatively high nutrient levels and low dissolved oxygen levels, both of which are known to be detrimental to trout. With causes and solutions to the Big Hole’s problems still uncertain, O’Neill thinks that people shouldn’t just wait around for answers.
“A penny of prevention equals a pound of cure, right? You can’t turn back the clock on all of these fisheries and try to put that genie back in the bottle,” O’Neill says. “Restoring a fishery is hard versus taking proactive steps to maintain that fishery and not allowing it to collapse.”
Even with fewer fish in the river, anglers have still been having great days on the Big Hole—as we did in April. The trout were strong and healthy, energized by the cold water and hardy enough to endure a hook in the jaw.
“We’re trading numbers for size, so there’s bigger fish in the river now than there have been in 30 years,” Olsen says.
At one electrofishing stop last year, Olsen had three fish over 25 inches in his live well; he jokes that the only way he can catch monsters like that is by shocking them. Still, river closures and high-water temperatures put a damper on fishing in 2024, and if temperatures remain high and the snowpack declines in the long run, best practices for anglers will become even more important.
“If water temperatures reach above 68 degrees, reel up, because these fish are so stressed and compromised,” O’Neill says, “that one catch can put them in a spiral.”
There’s no doubt about it: times are changing on the Big Hole. Twenty years ago, water temps were never even an issue. The river used to remain clogged with ice and snow until May in some years, and it would stay cool enough for trout to thrive all the way through the summer. But now, the climate is warmer, the snowpack less reliable, and trout must survive under these new conditions. Our environment is changing, and to sustain our wild-trout fisheries, the way we steward them will have to change, too.
