The two dolphins found dead in Amagansett had lacerations consistent with entanglement but their actual cause of death has not been determined, an official said.
The case was referred to NOAA’s law enforcement division, which investigates violations of regulations and laws that protect marine life.
Biologists from the Atlantic Marine Conservation Society, which evaluated the animals, said they conducted necropsies on Saturday and took tissue samples but were unable to determine cause of death without further investigation, said Rachel Bosworth, a spokeswoman for the society.
Bosworth said both animals had injuries consistent with becoming entangled with rope or line in the water. One appeared to have gotten tangled in material typically used for netting, she said.
Both bottlenose dolphins were female and between 5 and 13 years of age. One dolphin, determined to be 6.9 feet in length and 300 lbs., was found Friday afternoon on a beach at the end of Atlantic Avenue, she said.
The second was reported by a civilian on Saturday morning at a beach at the end of Napeague Lane. That dolphin was about 6.3 feet long and weighed 250 lbs.
With assistance from volunteers and East Hampton Marine Patrol, the society responded Saturday and moved the carcasses to the East Hampton Recycling Center to conduct investigations.
Bottlenose dolphins are common along the Atlantic Coast and live in temperate waters, according to the National Oceanic and Atmospheric Administration.
In a statement, Rob DiGiovanni, the society’s chief scientist, said these two dolphins appear to have been living further offshore than those that typically wash up in Long Island due to their size and age “as well as their body condition being free of marks commonly found on inshore dolphins,” he said.
This year, the society has responded to 109 marine mammals and sea turtles in New York State, DiGiovanni said.