“Trout populations in many streams in southwest Montana have seen decline in recent years, and research continues to point to perennially low stream flows and high water temperatures as contributing factors,” said Eileen Ryce, fisheries division administrator for FWP. “Though we don’t yet know all we’d like to about what’s happening in some of our most iconic rivers in southwest Montana, we can say that it starts with the amount of water in the river over the course of a year, and how warm that water is.”
High temperatures and low flows cause stress on fish, which in turns makes them more susceptible to disease impacts. Additionally, it makes recruitment from year to year more of a struggle.
“Coldwater fish like brown and rainbow trout really struggle in low, warm flows, particularly when this happens during spawning or after the eggs hatch,” Ryce said.
To limit additional stress on trout, FWP is marshalling resources to assess the impacts of angling on some of the rivers in southwest Montana. The new, in-depth effort will look closely at mortality and any performance or behavioral responses.
With the investment, FWP will also assess what is known about the contributions fish and habitat in tributary streams make to the mainstem waters and how those impact population numbers.
“FWP is committed to bringing more resources to bear to protect trout and get to the bottom of population declines in southwest Montana,” said Quentin Kujala, chief of conservation policy for FWP.
In the short term, FWP is proposing new angling restrictions on the Big Hole, Beaverhead and Ruby rivers to the Fish and Wildlife Commission at its June 8 meeting. Broadly, these restrictions would limit angling during the brown trout spawning season, as well as limit take in some stretches of water. (To see these regulation proposals, click here.) Some of the proposals deliberately establish regulation differences across multiple stretches to aid our comparative assessment of impacts.
Underlying these new and additional efforts, FWP will continue fish monitoring efforts around the region, which include sampling of dead and dying fish, as well as streamflow and temperature monitoring. FWP will also continue to look for opportunities to improve aquatic habitat and secure instream flow around the region.
“We have great partners around southwest Montana in our agriculture community,” Kujala said. “Late summer flows in many of our rivers are already dependent on irrigators leaving water in the rivers for the sake of the aquatic habitat.”
To comment on the proposed regulation changes, attend the June 8 commission meeting in person at FWP headquarters in Helena, or at any FWP regional office in the state. You can also attend virtually by signing up by noon on June 7, just click here.