Salmon swimming in heatwave-charged waters of the Pacific Northwest have broken out in flesh wounds and white fungus, disturbing new footage shows.
A pummelling heatwave hit the western US coast in past weeks, threatening human and animal life alike.
Footage from conservation group Columbia Riverkeeper, filmed on July 16, shows the native sockeye salmon swimming in the Little White Salmon river in Washington state, presenting signs of overheating and stress.
Sockeye salmon typically migrate upstream through the wide Columbia River to the ocean where they breed and spawn offspring – but divers filmed the fish diverting through a smaller tributary, in order to escape the superheated waters of the main river.
‘The sockeye salmon in the Columbia River are dying,’ said Don Sampson of the Northwest Tribal Salmon Alliance.
‘As you can see, they’re in lethally hot water. We’re in a salmon crisis.’
The fuzzy white patches seen in the video are likely a fungal infection caused by stress from the hot water.
The footage was recorded on a day when water temperatures were recorded being as high as 70F (21C), which can be lethal for fish if exposed for long periods.
Unlike humans, who can also lose heat by sweating, fish are cold-blooded, and derive their body temperature from the heat of the ocean around them.
That means swimming long distances in 70F water can be highly damaging to the fish.
The salmon filmed in the video are expected to die from their injuries, and, if they do survive, are unlikely to spawn offspring in their natural breeding grounds.
While Washington’s Clean Water Act prohibits river temperatures from rising over 68F (20C), the unprecedented heatwave meant authorities could do little to mitigate the harm.
The burst of heat, which was caused by a ‘heat dome’ over the region and exacerbated by climate change, killed hundreds of people in Western US states and Canada.
Scientists also estimate that the heatwave killed more than a billion sea creatures, as well as making wildfires across the region worse.
Columbia Riverkeeper argues that decades-old dams also contributed to the rise in water temperatures, but that the heatwave created a fatal combination.
Salmon populations are facing extinction throughout the Pacific Northwest, and scientists estimate that the death of a significant number of some species’ populations could have dire effects overall.
While Columbia Riverkeeper don’t have an estimate for the total number of salmon that have died so far, they estimate that thousands more could die over the coming months as rivers grow even hotter.
Divers that took footage of the Columbia river report seeing similar scenes in other tributaries, as well as salmon carcasses downstream.
In 2015, around 250,000 salmon died in the Columbia river after a summer heatwave.
With regular heatwaves from a warming climate, the problem is likely only to get worse