amedved via Getty Images The Bodega Head peninsula where mussels died in the heat.

In a chilling sign of climate change, thousands of mussels literally cooked to death in their shells as they lay in the sun on a hot day on a northern California shore.

The mid-June die-off is believed to be the worst in 15 years in the village of Bodega Bay, 60 miles north of San Francisco, where Alfred Hitchcock’s environmental horror movie “The Birds” was filmed.

“Every part of the mussel bed I touched, there were mussels that had died,” Bodega Marine Reserve research coordinator Jackie Sones told Bay Nature magazine.

Researchers along other sections of the northern coast reported other die-offs triggered by the unseasonable heat June 11.

The temperature at Bodega that day hit an unusually warm 75 degrees, and the mollusks were stranded in low tide in the daytime heat. There was no sea breeze to help with cooling.

Northeastern University marine ecologist Brian Helmuth told Bay Nature that on a day so warm, a mussel’s tissues glued to a rock out of water might rise to 105 degrees. “They were just literally cooking out there,” he said.

Typically, the hottest days along the northern California coast occur later in the summer, when the lowest tides happen early in the morning or at night when it’s cooler.

The mussel deaths will ripple through the ecosystem. It’s a foundation species that provides food and habitat for many other species.

Scientists fear such a gruesome discovery will become commonplace.

“We no longer think of climate change in the future,” Helmuth told Bay Nature. “It’s how do you prepare for it now.”

University of British Columbia biologist Christopher Harley told The Guardian that mussels are the “canaries in the coal mine for climate change — only this canary provides food and habitat for hundreds of other species.”