By Helena Dore BOZEMAN DAILY CHRONICLE
BOZEMAN – Montana’s fishing economy has proven resilient amid the impacts of drought, but a new study suggests that 35% of its cold water habitats could become unsuitable for trout by 2080, costing the state an estimated $192 million in annual revenue.
Scientists with the U.S. 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 in the journal Science Advances on Wednesday, the Bozeman Daily Chronicle reported.
“Trout fisheries have enormous cultural, economic and ecological importance in Montana and worldwide, yet even Montana’s resilient trout fisheries could be vulnerable to future climate change,” said Timothy Cline, a USGS scientist and the paper’s lead author, in a news release.
Cline and authors Clint Muhlfeld, Ryan Kovach, Robert Al-Chokhachy, David Schmetterling, Diane Whited and Abigail Lynch used Montana FWP’s recreation monitoring data to analyze how climate change impacted 3,100 miles of the state’s rivers between 1983 and 2017.
They found that the concentration of anglers doubled overall within that 34-year time period, and severe drought conditions, which drive stream flows down and water temperatures up, significantly impacted how that fishing pressure was distributed across the landscape.
When temperatures warmed and flows dropped on certain rivers, anglers flocked to other areas where waters were colder. These cold-water segments supported 10 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 favorable during drought, visitors kept trout fishing revenue in the state rather than choosing to travel elsewhere,” Cline said in the press release. “Trout fishing in Montana has been remarkably resilient to changing conditions.”
In contrast, resident anglers were less willing to travel to other areas in response to drought, and they often continued to fish along rivers by their homes, even when the conditions were stressful on trout, according to Cline.
While Montana’s fishing economy has demonstrated resilience during past periods of drought—particularly those in the late 1980s, early 2000s and in 2017—Cline said he expects new challenges will emerge as the climate warms throughout the coming decades.
“Montana’s fisheries are renowned for their trout, and trout require cold, clean, connected habitat to survive,” he said. “As the climate warms, a lot of those attributes are changing rapidly.”
Trout generally require water with temperatures below 70 degrees Fahrenheit. As temperatures rise, they don’t do as well, 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 put 30% of current angler spending at risk, which amounts to about 21% of the total annual fishing economy in the region, according to the study.
Critical pieces of cold-water habitat have allowed anglers to keep fishing for trout when other major rivers are closed, and maintaining as many of those features on the landscape as possible can help ensure that the fishing economy remains robust, Cline said.
“When we think of the most productive rivers, we think of places like the Madison and Blackfoot, but under stressful conditions like drought, anglers need to find different opportunities,” he said.
Smaller, colder habitats—like streams that are fed by groundwater—are critical, but they often get overlooked.