WISE RIVER – Fisheries staff with Montana Fish, Wildlife & Parks are conducting annual fish population estimates in the Big Hole River. Estimates from two of the four sampling areas are completed, showing several increases in trout numbers from historic lows last year.

In the Melrose section, which is immediately downstream of Salmon Fly Fishing Access Site, biologists found an estimated 192 rainbow trout per mile and 506 brown trout per mile. These figures are increases from 2023 estimates, which were 161 rainbow trout and 324 brown trout. Both estimates for 2024 still remain well below the long-term averages, which are 488 rainbow trout and 908 brown trout per mile.

In the Hogback section, which runs from Glen Fishing Access Site to Tony Schoonen Fishing Access Site, biologists found an estimated 263 rainbow trout per mile and 722 brown trout per mile. Rainbow trout numbers decreased slightly from 2023’s estimate of 288 fish. Brown trout estimates, however, more than doubled from last year’s estimate of 289 fish. The long-term averages for this section are 473 rainbow trout per mile and 920 brown trout per mile.

Jim Olsen, FWP’s fisheries biologist for the Big Hole River, says good water levels in 2023 likely helped improve the survival of juvenile trout because most of the population increase observed this year was in 2-year-old fish.

“While trout populations are still well below the long-term average, this year’s estimates so far are encouraging,” Olsen said.

Population estimates are still pending for the Jerry Creek and Pennington sections, which respectively include the upper and lower reaches of the Big Hole River. These results and updates from other waterbodies in the upper Missouri River Basin will be published as they become available.

FWP and Montana State University embarked on a new cooperative research effort when annual sampling found fish numbers to be at or near historic lows in sections of the Big Hole, Beaverhead and Ruby rivers last year. This partnership includes hiring three PhD students and additional staff to study fish mortality, recruitment and health.

This spring, FWP staff tagged fish in the three rivers, as well as the lower Madison River. As anglers report each tagged fish they catch, they’re helping researchers identify individual fish and monitor their health, survival, movement and other indicators over time. Anglers who submit reports could also be eligible for rewards.

To learn more about the research effort and how to report a tagged fish, click here.

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