Fraser River so warm it may kill migrating sockeye salmon

Photo: A worker with Fisheries and Oceans Canada tosses a sockeye salmon back into the water during tagging on the Adams River, a tributary of the Fraser, in October 2006. (Andy Clark/Reuters)

Waters staying above 20 C (68° F) for days, which causes high stress and ‘pre-spawn mortality’ in fish, DFO says

Sockeye salmon are on a mission up B.C.’s Fraser River right now, swimming "a marathon a day" to reach the gravel beds where they’ll lay eggs for the next generation. But the waters of the Fraser — historically one of the world’s great salmon rivers — have been so warm this week, fisheries officials say the migrating sockeye are in danger of dying before they have a chance to spawn.

Daily temperature monitoring by Fisheries and Oceans Canada shows the Fraser hitting 20.7 C near Hope, B.C., for some days this week. "It’s very warm," said Mike Lapointe, chief biologist of the Pacific Salmon Commission. "A fish experiencing … these kinds of temperatures, when they’re migrating a marathon a day, it makes a big difference."

‘High pre-spawn mortality’ of sockeye salmon

As waters warm, every degree matters. At 18 C, the sockeye don’t swim as well, according to Fisheries and Oceans Canada. Hit 19 C, they slow and show signs of physiological stress.

Days of 20 C and higher lead […]

Full article: Fraser River is now so warm it may kill migrating sockeye salmon

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