A rescue crew from the Riverhead Foundation for Marine Research and Preservation euthanized an unresponsive and emaciated Risso's dolphin Tuesday afternoon after it was seen in waters off the Village of North Haven in Southampton.

The adult male was spotted Tuesday morning and Riverhead Foundation arrived on scene just after noon. The 91/2-foot long, 600-pound dolphin was removed from the water in Sag Harbor and was found to have parasites, Riverhead spokeswoman Rachel Bosworth said in a statement.

"Due to the animal's poor condition, the most humane course of action was to euthanize the dolphin as rehabilitation would not have been successful," Bosworth said.

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A necropsy to determine cause of death is scheduled for Wednesday.

Risso's dolphins are typically found further offshore and there are about 13,000 to 20,500 in the Western North Atlantic, according to the National Marine Fisheries Service's Office of Protected Resources.