The carcass of a bottlenose dolphin washed up at Smith Point Park on Fire Island about 1 p.m. Thursday, officials said.
"It had been dead for 48 hours and was badly scavenged, so there was little we could determine," said Richard DiGiovanni, director of the Riverhead Foundation for Marine Research and Preservation.
He said a necropsy would be performed on the 8-foot dolphin in the coming days to try to determine what caused the death, "but it's so badly scavenged that there's not a lot to work with."
A Smith Point Park spokeswoman said it was not unusual for a dead dolphin to wash ashore. "It happens all the time."
Anne Marie McCormack, 52, of Selden, said she and her daughter Danielle, 18, watched as park workers carted off the dolphin shortly before 2 p.m.
At first, her daughter and a few others present thought it was a turtle because only the head was visible. "It's terrible," she said during a telephone interview as the carcass was taken away.