Declining trout population in southwest Montana prompts research and advocacy push

This story is excerpted from the MT Lowdown, a weekly newsletter digest containing original reporting and analysis published every Friday.

Marked declines in trout populations across several of Montana’s iconic fisheries have led a group of anglers, fishing guides and community members to launch a “Save Wild Trout” initiative in hopes of better understanding the cause of those declines.

Wade Fellin, co-owner of Big Hole Lodge, announced the launch of the privately funded effort on June 22. Save Wild Trout seeks to develop science-based solutions to the problem, which Fellin described as an “ecological emergency” affecting salmonid species in the Big Hole, Ruby, Beaverhead and Jefferson rivers. 

“We are near or at historic lows throughout the basin, with very few recruitment numbers for younger trout — and no one knows exactly what’s causing the crash,” Fellin said in a video posted to the recently unveiled website. “It’s an emergency situation for one of the last intact, cold-water wild trout fisheries with Arctic grayling and westslope cutthroat in the Lower 48.”

Fellin added that Montana’s Department of Fish, Wildlife and Parks has yet to conduct testing on dead fish it collected last year, and while there are theories about the collapse of rainbow and brown trout populations — fungal diseases and bacterial outbreaks among them — the cause could lie in a confluence of factors. Nutrient pollution, algal blooms, angling pressure, and warmer, lower streamflows wrought by earlier snowmelt have been suggested as possibilities.

Fellin, who has fished rivers in the Jefferson basin for the better part of two decades, said his hunch is that it’s a “death by a thousands cuts” scenario, but better data could help establish key factors contributing to the fisheries’ decline. 

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“We can’t manage what we don’t know,” he said.

Part of the reason guides and conservation groups are so troubled by dismal trout counts is that the Big Hole isn’t in the midst of a poor water year. As of April 1 — when snowpacks tend to hold the most water — the Jefferson basin was sitting at about 167% of its 30-year April 1 mean, according to the Natural Resources Conservation Service’s water supply outlook. Recent U.S. Geological Survey streamflow measurements show that the Big Hole near Melrose is a tad bit low relative to the 99-year median but still well within the typical range for this time of year.

According to Mike Duncan, FWP’s acting Region 3 fisheries director, the department’s electrofishing surveys are really only able to count larger fish, which could help explain why the Big Hole’s 2022 and 2023 trout counts are so low, even though both were decent water years. Duncan said the Big Hole’s trout population could still be recovering from 2021 — a uniquely terrible year for cold-water fisheries in the state — and any population gains wrought by higher streamflows the past two years won’t be reflected in their electrofishing data until next spring.  

Fellin said outfitters who’ve joined Save Wild Trout have committed to protective measures to protect the fishery (e.g., catch-and-release angling only, stowing double-barbed hook lures, nixing grip-and-grin photos, and calling it quits for the day when stream temperatures exceed 68 degrees).

The economies of rural communities such as Wise River, Melrose and Twin Bridges are also threatened by the declines, Fellin said. The fisheries that help sustain those communities demand that “we act boldly and decisively,” he said. A release about the launch of Save Wild Trout also noted that concerned citizens and organizations have for three consecutive years pitched Gov. Greg Gianforte on the development of a cold water fisheries task force composed of experts in biology, water quality and water quantity — to no avail. 

Brian Wheeler, executive director of the Big Hole River Foundation, said his organization is stepping up to fill in research gaps to supplement FWP’s data. For three years, he’s been collecting water quality samples to measure nutrients in the Big Hole and garner information on its dissolved oxygen levels. (Dissolved oxygen is critical both to trout and the aquatic invertebrates that sustain them.)

Wheeler said he’s appreciative that the agency has committed to starting a mortality study to better understand what trout are succumbing to and hopeful that samples he’s collected will provide a fuller picture. For now, he said, he’s appreciative of the “nimble” approach that can be leveraged by a private effort like Save Wild Trout. He said he’s also hopeful that better research can answer questions posed by both population data and on-the-ground observations reported by those in the southwest Montana angling community.

In a June 23 conversation with MTFP, he raised several such questions. He wondered why rainbow trout haven’t risen as brown trout decline, why the fishery appears not to have recovered from a 2017 saprolegnia fungus outbreak despite a few decent water years in the ensuing period, and if some of the decline might be attributed to increased recreational pressure, particularly from do-it-yourself anglers. (The number of summertime outfitter days on the Big Hole was capped years ago, but there does appear to be an increase in non-outfitted anglers wetting a line in the Big Hole, he said.) If increasing levels of nitrogen and phosphorus play a role, he’s curious if an impairment designation might shift the fishery’s trajectory.

Wheeler said he’s also perplexed that the Big Hole is being hit so hard since other rivers with similar streamflow trends — not to mention significantly more recreational pressure — aren’t being affected the way the Big Hole is. 

“There’s something unique going on,” he said. “Fisheries biologists are not seeing disease-riddled fish in other watersheds that have these problems.”

For its part, the state Fish and Wildlife Commission voted June 8 to adopt angling restrictions on stretches of the Big Hole, Beaverhead and Ruby rivers. Though summertime “hoot owl” (afternoon) closures are common on those rivers, they aren’t typically implemented this early in the season. The restrictions were triggered by population data showing that stretches of the Big Hole River, for example, have dipped well below the 25th percentile in terms of trout-per-mile counts. 

The restrictions adopted by the commission vary from river to river, and even within different stretches of the same river. Details are available here.