BOZEMAN, Mont. (`) — Montana’s fishing industry has shown resilience in the face of drought impacts, but a new study suggests 35% of its cold-water habitats could become unsuitable for trout by 2080, costing the state an estimated $192 million in annual income would cost.
Scientists from the US Geological Survey, Montana Fish, Wildlife and Parks and the University of Montana contributed to the new study, titled Socioeconomic Resilience to Climatic Extremes in a Freshwater Fishery. It ran Wednesday in Science Advances magazine, the Bozeman Daily Chronicle reported.
“The trout fishery has tremendous cultural, economic, and environmental importance in Montana and globally, but even Montana’s resilient trout fishery could be vulnerable to future climate change,” said Timothy Cline, a USGS scientist and lead author of the paper, in a news release.
Cline and authors Clint Muhlfeld, Ryan Kovach, Robert Al-Chokhachy, David Butterfly, Diane Whited, and Abigail Lynch used Montana FWP recovery monitoring data to analyze how climate change affected 3,100 miles of the state’s rivers between 1983 and 2017 Has.
They found that the overall concentration of anglers doubled over that 34-year period and that severe drought conditions, driving currents down and water temperatures up, significantly affected the distribution of fishing pressure across the landscape.
As temperatures in certain rivers warmed and currents receded, anglers flocked to other areas where the water was colder. These cold-water segments supported ten times more anglers than warm-water segments, and most of them were from out of state.
“By moving to other fishing areas that were more affordable during the drought, visitors kept trout fishing revenue in the state rather than choosing to travel elsewhere,” Cline said in the release. “Montana trout fishing has been remarkably resilient to changing conditions.”
In contrast, resident anglers have been less willing to travel to other areas in response to drought, and they often continue fishing along rivers near their homes even when conditions have been stressful for trout, Cline says.
While Montana’s fisheries economy has shown resilience during past droughts — particularly in the late 1980s, early 2000s and into 2017 — Cline expects new challenges will arise as the climate warms in the coming decades.
“Montana’s fishing grounds are known for their trout, and trout need a cold, clean, and connected habitat to survive,” he said. “As the climate warms, many of these attributes are changing rapidly.”
Trout generally require water with temperatures below 70 degrees Fahrenheit. They don’t fare as well when temperatures rise, and other species tend to thrive, Cline said.
About 35% of Montana’s cold-water habitat could become unsuitable for trout by 2080, and the losses could threaten 30% of anglers’ current spending, which accounts for about 21% of the region’s total annual fisheries economy, according to the study.
Critical parts of the cold-water habitat have allowed anglers to fish for trout when other major rivers are closed, and preserving as many of these features in the landscape as possible can help keep the fishing industry robust, Cline said.
“When we think of the most productive rivers, we think of places like Madison and Blackfoot, but under stressful conditions like drought, anglers have to find other options,” he said.
Smaller, colder habitats — like streams fed by groundwater — are critical but often overlooked.
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