A significant commotion caused a substantial stir last year — similar to a large brown trout chasing after a salmonfly. The uproar and agitation were centered around the declining trout populations in the renowned Big Hole River since 2011.
In May 2023, over 30 fishing outfitters and guides in Montana urged Gov. Greg Gianforte to take quick action to utilize state resources to investigate the reasons behind the decreasing trout populations in the river.
After more than two months, Gianforte organized a roundtable discussion in Wise River involving fishing guides, irrigators, agriculture producers, and biologists. The majority of attendees at the community center were people with agricultural interests.
Recently, Gianforte returned to the Wise River area to receive an update from Jim Olsen, a fisheries biologist for Montana Fish, Wildlife & Parks responsible for the Big Hole River. FWP Director Dustin Temple also attended the meeting.
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The update provided both positive and moderate news. A press release from the governor’s office highlighted the positive aspects.
The positive news revolved around electrofishing sampling conducted this spring by Olsen and his team, showing a general increase in juvenile fish, indicating improved recruitment of young fish that may grow into larger fish in the future.
The moderate news indicated that in all four sampled sections of the river, the numbers of brown and rainbow trout remained significantly below long-term averages. In certain sections like Hogback and Pennington, the numbers of rainbow trout had decreased either since last year’s sampling or compared to the data from 2021.
In the Melrose section of the river, the estimate in 2024 suggested 506 brown trout per mile, an increase from 324 per mile in 2023 but still below the long-term average of 908 per mile for that stretch.
Similarly, in the Jerry Creek section, the estimate for brown trout was 710 per mile, the highest count since 2015 and an improvement from 422 in 2023. However, this figure was still below the long-term average of 749 per mile.
Rainbow trout numbers in the Jerry Creek section rose from 498 per mile in 2023 to 779 per mile in 2024, but this was lower than the long-term average of 1,606 per mile for this stretch.
For the Hogback section, which runs from the Glen Fishing Access Site to the Tony Schoonen Fishing Access Site, biologists recorded 268 rainbow trout per mile and 722 brown trout per mile. While rainbow trout numbers slightly decreased from 288 in 2023, brown trout estimates more than doubled from the previous year’s count of 289. The long-term averages for this section are 473 rainbow trout per mile and 920 brown trout per mile.
Olsen mentioned that the favorable water levels in 2023 likely contributed to the increased survival of juvenile trout, as most of the population growth observed this year involved 2-year-old fish.
“Although trout populations are still below the long-term average, this year’s estimates are promising,” Olsen stated earlier in the year.
A Cautionary Note
Wade Fellin, an outfitter, co-owner of the Big Hole Lodge, and a co-founder of the nonprofit Save Wild Trout, responded to the data.
“While seeing incremental increases in wild trout populations is definitely a reason for celebration, we should remain cautious before jumping to conclusions,” Fellin cautioned. “FWP biologists have taken important steps in conducting studies to identify the factors affecting trout populations, but creating resilience in our waterways cannot be achieved by them alone. Healthy cold-water fisheries that sustain strong wild trout populations require a balance of biological, physical, and chemical factors to thrive.”
Fellin highlighted that the Big Hole River and many other high-quality waterways are facing ongoing pollution levels exceeding acceptable limits, along with rising temperatures due to climate change, creating an unnatural environment unsustainable for fishery health.
“Montana still needs to address these underlying issues,” he emphasized. “Save Wild Trout and the Big Hole River Foundation are collecting essential water chemistry and macroinvertebrate data to support the conservation of these rivers.”
The Big Hole River Foundation has been gathering water quality data on the Big Hole for several years, with the approval of the Montana Department of Environmental Quality for their sampling and analysis plan in 2020.
Brian Wheeler, the foundation’s executive director, has been actively collecting water samples along the Big Hole to monitor water quality.
He noted that DEQ’s assessment of the river includes temperature, sediment, nutrients, and heavy metals as potential pollutants, with dissolved oxygen being a critical parameter for aquatic life that has recently been addressed through projects by the Big Hole River Foundation and Save Wild Trout to monitor oxygen levels in the Jefferson Basin.
Unanswered Questions about Disease
Olsen presented data on fish numbers and health during a meeting of the Big Hole Watershed Committee in Divide on May 15.
Observers in recent years have photographed trout in the Big Hole showing signs of fungus or head lesions.
According to Olsen, the presence of fungus is not uncommon, but the issue with head lesions remains unclear. He expressed gratitude for the collaborative efforts to understand this disease concern.
He stressed that the primary factor in maintaining a healthy trout population is ensuring an adequate flow of water, especially cold water, in the river.
During low-water years, such as 2024 appears to be, tensions often rise between hayfield irrigating ranchers preparing for the long winter in the Big Hole Valley and outfitters and guides relying on summer activities for their livelihoods.
Monitoring River Conditions
The Natural Resources Conservation Service predicts that the Jefferson River Basin will experience 50% to 60% of normal streamflow through July.
When water levels decrease and temperatures rise, FWP typically closes sections of the river for fishing to prevent further stress on fish populations.
Last year, Eileen Ryce, then the agency’s fisheries division administrator, addressed the challenge of low flows.
“Trout populations in many streams in southwest Montana have seen decline in recent years, and research continues to point to perennially low stream flows and high water temperatures as contributing factors,” Ryce stated previously.
Recently, without explanation, Ryce was placed on administrative leave.
FWP and Montana State University embarked on a collaborative research effort following the discovery of historically low fish numbers in sections of the Big Hole, Beaverhead, and Ruby rivers last year. This partnership involved hiring PhD students and additional staff to study fish mortality, recruitment, and health.
Spring population sampling revealed similar trends in the Beaverhead and Ruby rivers, with numbers showing some improvement compared to last year but still below long-term averages.
This spring, FWP tagged fish in the three rivers, as well as the lower Madison River. Anglers reporting tagged fish can assist researchers in tracking individual fish and monitoring their health, movements, and other indicators over time, with the potential for rewards for submitting reports.
Reactions and Responses
However, some outfitters and guides voiced complaints this spring, believing that the negative publicity surrounding declining trout populations last year was exaggerated and had a detrimental impact on their businesses.
Many reported that fishing during the summer of 2023 was generally positive.
Shaun Jeszenka, the owner of Frontier Anglers in Dillon, expressed that negative media coverage created an overly pessimistic view of fishing conditions in the Jefferson River Basin.
As the salmonfly hatch began, Jeszenka was guiding clients, but Steve Wilson, the shop manager at Frontier Anglers, noted that fishing experiences this month aligned with the more optimistic population estimates.
