In a new study published in Science Advances, University of Montana researchers found that climate change drives native trout declines by reducing stream habitat and facilitating the expansion of invasive trout species.
In a new study published in Science Advances, University of Montana researchers found that climate change drives native trout declines by reducing stream habitat and facilitating the expansion of invasive trout species.
“This study had three main questions: How have the distributions of native and invasive trout shifted in Montana over the last 30 years, how will they change in the future, and what factors are causing those changes?” said Donovan Bell, the study’s lead author and a doctoral candidate in UM’s Wildlife Biology Program.
To answer those questions, scientists from UM, the U.S. Geological Survey and Montana Fish, Wildlife & Parks quantified the impacts of climate change on the distributions of five trout species (native westslope cutthroat trout and bull trout and invasive brook trout, brown trout and rainbow trout) in the northern Rocky Mountains. They used an expansive long-term dataset collected and maintained by Montana FWP, analyzing close to 22,000 data points from electrofishing surveys in Montana’s streams and rivers over the past 30 years.
The researchers found native bull trout and westslope cutthroat trout occupancy – defined as the amount of stream where a species is present – declined by 18% and 6%, respectively, between 1993 and 2018 and are predicted to decrease by an additional 39% and 16% by 2080. Although invasive brook trout also were expected to decline, invasive brown and rainbow trout have expanded their range due to rising water temperatures and appear poised to prosper during future climate change.
Read more at The University of Montana
Image: Westslope cutthroat trout and a bull trout swim in the Flathead River system of Montana. (Credit: Courtesy of Jonny Armstrong, USGS)
