It’s not unusual for sea turtles to wash up on the shores of New England at this time of year. It is unusual for over 200 to turn up in just a few days, many of them already dead due to being “flash frozen” by the recent cold snap.

Local wildlife sanctuaries and aquariums are seasoned pros at rescuing the turtles, many of them critically endangered Kemp's ridley sea turtles, that often find themselves stranded on this part of the East Coast each year.

Before 2010, the Gulf of Maine was too cold for turtles to enter but thanks to climate change and global sea temperatures rising the turtles not only follow the good food and warm waters, they nest here too. As the warm water turns colder, the turtles then migrate south, but many get caught in the hook of the Cape, hemmed in by the now too-cold water.

Hundreds of volunteers each fall start patrolling the beaches of Cape Cod looking for stranded turtles to rescue and rehabilitate.

In the last few days, however, thanks to an unseasonably cold snap, the number of turtles that have washed up so far is 227 and counting, and many of them were frozen solid and dead when found.

“It was like they were flash-frozen, flippers in all weird positions like they were swimming,” Robert Prescott, director of Massachusetts Audubon Society’s Wellfleet Bay Wildlife Sanctuary, told the Cape Cod Times.

Of the 82 found on Thanksgiving day, only one was found alive. Prescott told CNN that 173 of the turtles found in the last few days have died – many young Kemp’s ridleys, the smallest tropical turtle species and the most endangered turtle in the world – and 54 have survived and are currently being rehabilitated at the New England Aquarium’s Animal Care Center.

Other species like this 135-kilogram (300-pound) loggerhead have been found “cold-stunned” in the region too.

Like most reptiles, turtles are ectothermic – they are cold-blooded and so have to regulate their body temperature using their surroundings – so can only be as warm as the sea around them.

“Cold stun” stranding, as rescuers refer to it, is what happens when tropical animals like turtles suddenly find themselves in rapidly cooling water. When it reaches 10°C (50°F) or below, their bodies slow down, they stop eating, they stop swimming, and get washed ashore in a cold-stunned state.  

“Their systems are shutting down, they look dead, but they are still alive,” Jenette Kerr, also of the Wellfleet Bay Wildlife Sanctuary, told Earther. “If we get them quickly to the New England Aquarium’s rehab facility, their chances of recovering are very high.”

Over the past couple of days, the temperature has been a couple of degrees higher, meaning more turtles have been found alive.

So far this fall 500 turtles have been discovered, which is high for so early in the season, though Prescott is predicting a record year and that figure could be 1,000 by Christmas.