Thousands of dead mussels washed up in Jamesport this week, and one expert says they could be victims of this summer’s heat waves.

The shellfish carcasses began washing up near Iron Pier Beach after a storm on Monday, said resident Eileen Fenton, and “thousands and thousands and thousands” of mussels have lined the beach for a stretch of at least a mile for several days.

“There were high waves in the Sound,” Fenton, 70, said Thursday afternoon. “The next thing we knew, there were piles of mussels on the beach.”

The mussels recalled the massive fish die-off in May 2015, when thousands of dead bunker fish floated to the surface in the Peconic Estuary. In that incident, Riverhead town officials declared a state of emergency until the fish could be cleaned up.

However, Christopher Gobler, a Stony Brook marine science professor, said he examined the mussels Thursday and doesn’t believe there is much in common with the fish die-off. That took place in Flanders Bay after predator fish chased the bunker fish into shallow estuaries with low oxygen from blooming algae and seasonally warm water, authorities said.

Gobler identified the mussels as blue mussels, which thrive in the Long Island Sound’s typically mild temperatures. But this summer, temperatures have heated up. He believes all the mussels were all born in late 2013 or 2014, both cooler years.

advertisement | advertise on newsday

“The last two summers were quite cool and so they did just fine,” Gobler said. “They do well in mild temperatures, but when they hit the high temperatures, they’re done for. It seems to me temperature is the best explainer.”

Gobler said by his analysis, the sound’s water temperature spiked as Long Island’s overall summer highs spiked up through the 90s for several days this summer. Die-offs of shellfish are more typical on the South Shore, where the shallower bays are more prone to temperature spikes, he said.

"Hundreds of thousands" of mussels washed up on the shore in Jamesport, just west of Iron Pier Beach, Thursday, Aug. 25, 2016. Photo Credit: Randee Daddona

Town officials and the state Department of Environmental Conservation didn’t return requests for comment on Thursday.

Fenton said in her 41 years visiting the beach — 12 of those with a home on the waterfront — she’s never seen anything like it.

“We’re hoping that the tide will come in and take them out, because it’s starting to smell,” she said.