Climate Warming may Erase Native Cutthroat Trout

A non-native trout population has experienced accelerated growth in the northwest river system due to climate changes. 

From the vast river system of Montana and southern British Columbia, more than 20 million rainbow trout began mating with the river system's native cutthroat population throughout the 1800s till 1969, according to NBC News. However, the hybridization of this trout population may lead to extinction, according to Clint Muhfeld, a research ecologist at the U.S. Geological Survey in West Glacier, Mont.

"This is the first example we are aware of that has shown how invasive hybridization has probably spread due to climate warming," he said, via the news organization.

As rainbows typically thrive in warmer waters, the non-native trout are more confined to parts of the Flathead River system that's protected from the bitter waters and flooding.

Muhlfeld said he believes that the drought in the early 2000s may have caused warmer water temperatures and lower spring flows preferred by rainbows to encourage a crossover between the two types. Unfortunately, over time, researchers believe that the growing rainbow population will lead to the elimination of the native cutthroat trout.

Muhlfeld notes that hybridized fish with rainbow accounting for even 20 percent of their DNA are only half as fit as the original native fish with pure DNA. 

"This has important consequences," Muhlfeld added. "If our native fish are mostly hybridized and their fitness is lower, then their potential to be resilient and adapt in the face of climate change is going to be reduced."

More information regarding the findings can be seen via the journal Nature Climate Change.