Experts such as aquatic ecologist Robert Bilby say that with river temperatures increasing, the cold-water fish could soon find themselves fighting for survival, The (Portland) Oregonian reported Sunday.
Bilby, who helped assess the changing climate's impact on the U.S. salmon population, said the appearance of more than 100 dead salmon in a tributary of the Columbia was a warning sign.
"With a warming climate, these are the sorts of things we will probably see more of," Bilby said. "We're talking about the survival of a cold-water fish in warming conditions."
The Independent Scientific Advisory Board said that by the year 2040, river temperatures are expected to increase by nearly two degrees overall.
The Oregonian said a similar fate is facing cold-water-loving trout in the northwestern United States.