Reuters reports: Unseasonably hot water has killed nearly half of the sockeye salmon migrating up the Columbia River through Oregon and Washington state, a wildlife official said on Monday.

Only 272,000 out of the more than 507,000 sockeye salmon that have swum between two dams along a stretch of the lower Columbia River have survived the journey, said Oregon Department of Fish and Wildlife fisheries manager John North.

“We’ve never had mortalities at this scale,” said North.

The die-off comes as U.S. West Coast states grapple with drought conditions and the Columbia is seeing the third-highest count of sockeye returning from the ocean to spawn since 1960, federal figures show. [Continue reading…]