A 279-pound sea turtle was found on an Eastham beach Thursday, the largest hard-shell turtle in recent memory to be discovered after washing ashore in Massachusetts, wildlife officials said.
The adult loggerhead turtle was among hundreds of sea turtles that have washed ashore along Cape Cod in the past week, said Bob Prescot, director of the Massachusetts Audubon Society’s Wellfleet Bay Wildlife Sanctuary.
Prescott said the loggerhead that was found Thursday “was very compromised in her ability to swim because she only has one good flipper,” Prescott said. “The other ones had been nibbled off, or bitten off at some point.”
The turtle died Thursday evening, New England Aquarium spokesman Tony LaCasse said. The cause has yet to be determined, he said.
An average adult loggerhead weighs about 250 pounds, according to the National Oceanic and Atmospheric Administration. The last hard-shell turtle closest to that size that Mass Audubon has found washed ashore in the area was an adult loggerhead discovered in 1999, but it weighed almost 100 pounds less, Prescott said.
Soft-shell leatherback turtles that weighed as much as 700 pounds have been found washed up on Massachusetts shores, LaCasse said.
About 500 turtles have washed ashore along Cape Cod Bay this month, Prescott said. In the past few days, about 50 have washed up with each high tide, which he said was an unprecedented amount.
“This year we could double our previous record in 2012 of 413 turtles” for the entire year, Prescott said.
Prescott said the increase in the number of turtles washed ashore in Massachusetts can be explained by increased conservation efforts, and the fact that the Gulf of Maine is generally warmer than in the past.
“Instead of them stopping around New Jersey . . . or the southern tip of Cape Cod because the waters would be too cold farther up, now they are coming up past Boston and up into Canada,” Prescott said.
When the sun sets, the wind increases and the temperatures abruptly drop, and the turtles become slower and weaker against the tides — causing them to wash up on the Cape Cod Bay shoreline by the dozens, Prescott said.
Maggie Mooney-Seus, an NOAA spokeswoman, said it is unusual for a turtle as large as the loggerhead found on First Encounter Beach in Eastham Thursday to be affected by the colder waters.
“Typically, cold stunning affects smaller animals because they don’t have as much body mass,” she said. “A bigger animal, like a loggerhead, would have more body fat and deal with the cold better.”
Loggerheads washed ashore are typically much smaller, and are usually not seen until the end of November through December. Mooney-Seus said it is likely the animal’s damaged flippers played a large factor in it being washed ashore.
Volunteers from Mass Audubon gather turtles they discover on beaches and bring them to the society’s Wellfleet Bay sanctuary for evaluation and care until they are taken to the New England Aquarium, where they are cared for until they recover.
Although loggerheads are sometimes found in the area, finding an adult is unusual, Prescott said. About 80 percent of the turtles that wash up on shore have been Kemp’s ridley sea turtles, while the other 20 percent are either loggerheads or green sea turtles.
Prescott said the loggerhead turtle found by a volunteer Thursday was between 50 and 70 years old.
She was “a great old lady of the turtle world,” Prescott said.Trisha Thadani can be reached at email@example.com. Follow her on Twitter @TrishaThadani