By Diana Setterberg, MSU News Service
BOZEMAN – A new, interactive web tool amassing data from all over Montana was launched Monday, June 1, to help forecast drought impacts on trout populations and support fisheries and water management in the state's blue-ribbon rivers.
The tool, called FishCast , integrates weather information, historic trout population data and streamflow records to predict drought risk, trout population trends and the likelihood of drought-related fishing closures. The information will be displayed in real time on the USGS website for fisheries managers and the public.
The tool was developed through a collaboration between Montana State University, the U.S. Geological Survey, Montana Fish, Wildlife and Parks, and NOAA's National Integrated Drought Information System.
FishCast's population tool provides one-year forecasts of trout populations and shows whether those populations are expected to increase, remain stable or decline compared with recent population trends. Managers can use the tool to evaluate how trout populations are responding to drought, compare conditions across rivers and better understand where streamflow may be most important for sustaining productive fisheries.
The management tool forecasts, up to a month in advance, drought-related fishing closures or restrictions that prohibit fishing at certain times of day. Anglers and outfitters can use the tool to see where drought may affect fishing opportunities and identify alternative waters across Montana where conditions may be better. New users can learn to navigate the tool through built-in tutorials.
The trout population forecasts are based on new models developed by Timothy Cline, an assistant professor of cold-water fish ecology in MSU's Department of Ecology in the College of Letters and Science , and scientists at the USGS Northern Rocky Mountain Science Center. The aim of the collaborative project, funded by NOAA and USGS, was to understand how reduced streamflows and elevated water temperatures, caused by increasing drought frequency and severity across the West, are related to trout population declines.
"What we've found is that it's basically driven by streamflow," Cline said. "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."
Cline and collaborators analyzed historical population data from Montana FWP and streamflow data from USGS to develop the age-structured trout population models that have been incorporated into FishCast. Those models allow FishCast to translate streamflow changes into forecasts of trout abundance, productivity and long-term population trends.
"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 of the USGS Northern Rocky Mountain Science Center, one of the project scientists.
Even a small difference in the amount of water carried by a stream can affect trout populations dramatically, said Cline, and users will be able to use the slider function on FishCast's population tool to see the correlation. He cited as an example the Ruby River, which supports 384 fish per mile at a streamflow rate of 140 cubic feet of water per second. If the streamflow increases in the Ruby by 20 cfs, the population of fish per square mile may nearly double to 784.
"That's what we really hope this tool gets used for," Cline said.
Beyond fisheries conservation, the tool is expected to benefit local and regional economies by helping sustain recreational fishing opportunities and improve predictability around drought-related management decisions. Cline said outfitters he has spoken with are excited about FishCast's potential to help them plan ahead to sustain their businesses, even amid drought conditions.
"This tool revolutionizes the state's ability to communicate trends in fish populations, manage angling opportunities and inform instream flows," said David Schmetterling, fisheries research coordinator for Montana Fish, Wildlife and Parks.
The multi-agency effort to develop FishCast supports Montana's Drought Management Plan , the USGS Integrated Drought Science Strategy and the NOAA National Integrated Drought Information System by improving drought early warning and providing actionable, scientific information for natural resource management. The tool's initial rollout focuses on Montana's rivers, with planned expansion to the upper Snake River basin in Idaho and Wyoming, followed by broader applications across additional drought-affected western states.
FishCast will go live on Monday, June 1, at www.usgs.gov/apps/fishcast.
"It's really a testament to a lot of great agency collaboration and turning science into practical tools to conserve our really valuable trout fisheries here in Montana," Cline said.
