Estimates show population increases in many areas
BOZEMAN – Fisheries staff with Montana Fish, Wildlife & Parks have completed spring sampling, which provides estimates for trout abundances in southwestern Montana rivers.
Results from these surveys are now available, along with abundance estimates from rivers that were sampled last fall.
Spring sampling 2026
This spring, fisheries staff sampled areas of the Beaverhead, Big Hole, Boulder (Jefferson County), lower Madison, Jefferson and Ruby rivers.
Most sampling sections in the Beaverhead River have shown marked improvement in trout abundances over the past two years. Brown trout abundances are above average in the Hildreth, Pipe Organ and Poindexter sampling sections. Brown trout abundances are near average in the Fish & Game section, and rainbow trout are well below average in the Hildreth section.
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The Big Hole River showed mixed results, with trout abundances improving in the Jerry Creek and Pennington sections and estimates in the Melrose and Hogback sections declining or remaining stable below the long-term average. A summary of estimates for the Big Hole River is available here.
The lower Madison River near Norris showed encouraging signs with stable abundances of brown trout and several consecutive years of increases in rainbow trout abundances, though both species remain below average. Westslope cutthroat trout presumably moving out of Cherry Creek can still be found in low but stable abundances in the lower Madison.
Trout abundances in the sampled areas of the Jefferson, Boulder and Ruby rivers remain below long-term averages.
Fall sampling 2025
Trout sampling for the Gallatin and upper Madison rivers happens in the fall.
Fall estimates from the Madison River’s two upper sections—Pine Butte and Varney—were both at or near long-term estimates for combined trout, with an exceptionally high number of rainbow trout in the Pine Butte section.
Rainbow trout abundance in the Gallatin River near Big Sky last fall were well above the long-term average, with brown trout abundance estimated to be similar to the long-term average.
Collaborative research
FWP and MSU are continuing joint research to better understand the major limiting factors contributing to low trout populations in the Big Hole, Beaverhead and Ruby rivers. Annual interim reports from the past two years of these studies can be found on FWP’s website.
This year’s spring sampling marked the third and final year of tagging trout in the Big Hole, Beaverhead, Ruby and lower Madison rivers, with tagging in the upper Madison River slated for this fall. Staff will continue monitoring tagged fish for the coming years to better understand how environmental conditions, such as water temperature and flows, influence survival, as well as potential angling effects.
Anglers who report catching tagged fish substantively contribute to the informed management of these fisheries by helping researchers identify individual fish. FWP and MSU have partnered with Montana Trout Unlimited to host drawings for guided fishing trips, equipment and other prizes for anglers who submit reports of catching fish with blue tags. Yellow tag reports are each worth a prize of $100. Reward opportunities will continue in 2026.
To learn more about the research effort and how to report a tagged fish, click here.
MSU is again collecting surveys of recreationists on the Big Hole, Beaverhead, Ruby, Madison and upper Yellowstone rivers. Anglers and other recreationists may see creel clerks helping collect this information. This study will help FWP and partners better manage recreational use and resources around popular rivers in southwestern Montana.
