FishCast launches in Bozeman to track drought risk for trout rivers

BOZEMAN, Mont. — Montana State University (MSU) has launched a new online tool to help forecast how drought could affect trout populations and fishing access on Montana’s blue-ribbon rivers.

MSU developed FishCast with the U.S. Geological Survey, Montana Fish, Wildlife and Parks and NOAA’s National Integrated Drought Information System.

The tool combines weather data, streamflow records and historic trout population information to show drought risk, trout trends and the chance of drought-related fishing restrictions in real time.

Timothy Cline, an assistant professor in Montana State’s Department of Ecology, developed the trout forecast models with scientists at the USGS Northern Rocky Mountain Science Center.

He said the project examines how lower flows and warmer water linked to more frequent and more severe drought were tied to declining trout populations.

“What we’ve found is that it’s basically driven by streamflow,” Cline said in a release. “Of course, water is important to fish – it’s the thing that makes them fish. But until now, we’ve never really known exactly how valuable that water is for fish production and abundance.”

The tool includes a population forecast that looks one year ahead and shows whether trout numbers are expected to rise, stay steady or fall compared with recent trends. It also includes a management forecast that looked as far as a month ahead for possible fishing restrictions or closures tied to drought.

The university said even modest changes in streamflow could make a major difference. In the Ruby River, Cline said, a flow of 140 cubic feet per second supported 384 fish per mile, while an increase of 20 cubic feet per second could raise that to 784.

“FishCast links streamflow and temperature conditions with trout population responses, enabling proactive, science-based decision making that supports sustainable fisheries, recreational opportunities and the long-term resilience of freshwater resources in the face of drought and changing river flows,” said Clint Muhlfeld USGS Northern Rocky Mountain Science Center, one of the project scientists.

FishCast’s first rollout focuses on Montana rivers, with future expansion planned for the upper Snake River basin in Idaho and Wyoming and later other drought-affected Western states. New users can also access built-in tutorials on the site.