Montana fly fishing guide and shop owner Jason Lanier hooks a feisty rainbow trout almost every day he hits the waters in the lower valley of the Flathead River system. From an angler’s perspective, the catch is a thrill. Rainbows put up a good fight, much better than the one offered by the state’s native westslope cutthroat trout.
“And cutthroats that have some rainbow genetics in them typically fight harder for sure,” the owner of the Bigfork Anglers Fly Shop told NBC News.
About 20 million rainbows were stocked in the river system that spans Montana and southern British Columbia, Canada, from the late 1800s to 1969. The fish can, and do, mate with cutthroats. This hybridization may drive the genetically pure natives to extinction, according to Clint Muhlfeld, a research ecologist with the U.S. Geological Survey in West Glacier, Mont.
What’s more, climate change is accelerating the hybridization process, according to new research led by Muhlfeld. “This is the first example we are aware of that has shown how invasive hybridization has probably spread due to climate warming,” he told NBC News.