(CNN) A total of 173 sea turtles died off Cape Cod, Massachusetts, this week because of the extreme cold, according to Mass Audubon Director Bob Prescott.

Prescott said 227 cold-stunned turtles were recovered from the Gulf of Maine since Wednesday, but only 54 lived. Mass Audubon, the largest nature conservation nonprofit in Massachusetts, regularly patrols the beaches this time of year looking for cold-stunned turtles, Prescott said.

But this was many more than they expected, he said.

Volunteers process the incoming turtles this week at Mass Audubon's Wellfleet Bay Wildlife Sanctuary.

"This was way too cold," Prescott said. "Everything was slushy by yesterday morning. Some of them are small. It didn't take long for them to freeze."

Most sea turtles migrate between areas where they can find food and areas where they can give birth, and typically to warmer waters, according to SEE Turtles, a conservation tourism project that aims to protect sea turtles.

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