Salmon dying in too warm water

Red lesions and white fungus on the salmons’ bodies are the result of high water temperatures and stress. Photograph: Conrad Gowell/Courtesy of Columbia Riverkeeper

From The Guardian

Salmon in the Columbia River were exposed to unlivable water temperatures that caused them to break out in angry red lesions and white fungus in the wake of the Pacific north-west’s record-shattering heatwave, according to a conservation group that has documented the disturbing sight.

In a video released on Tuesday by the non-profit organization Columbia Riverkeeper, a group of sockeye salmon swimming in a tributary of the river can be seen covered in injuries the group say are the results of stress and overheating.

The salmon had been traveling upstream in the Columbia River from the ocean, to return to their natal spawning areas, when they unexpectedly changed course, explained Brett VandenHeuvel, the executive director of Columbia Riverkeeper. He described the sockeye as veering off to the Little White Salmon River, a tributary of the Columbia River where the video was recorded, in an effort to essentially “escape a burning building”.

The conservation group recorded the video following the heatwave on a day when water temperatures breached 70F (21C), a lethal temperature for these anadromous fish if they are exposed to it for long periods. The Clean Water Act prohibits the Columbia River from rising over 68F (20C).

VandenHeuvel compared the situation to a person trying to run a marathon in over 100F (38C) temperatures.

“The difference is that this isn’t recreation for the salmon,” he said. “They have no choice. They either make it or they die.”