The Riverhead Foundation for Marine Research responded Tuesday to a deceased humpback whale floating in the waters off Amagansett, the third such marine mammal discovery reported in recent days between Long Island and waters north of Cape Cod.

At this point, “it is not clear whether these incidents are at all related,” said foundation spokeswoman Rachel Bosworth, citing information from the National Oceanic and Atmospheric Administration.

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A team from the foundation joined Tuesday with East Hampton’s marine patrol to photograph and take samples from the dead humpback whale, first reported Sunday floating off Amagansett, officials said.

In recent days a dead humpback whale was discovered off Newport, Rhode Island, and a third deceased humpback was spotted in waters off Marshfield, Massachusetts, north of Cape Cod, Bosworth said.

The Riverhead foundation, as well as the Mystic Aquarium, in Mystic, Connecticut, responding to the Rhode Island whale, and the New England Aquarium, responding in Massachusetts, will report their findings to NOAA, Bosworth said.

With the three carcasses “in varying levels of decomposition,” the sense is that they died at different times, said Jennifer Goebel, a NOAA spokeswoman. In such situations, the aim is to test samples for any “harmful algal bloom,” to see if “environmental conditions could have contributed to the mortalities,” she said. When feasible, disease and the possibility of injuries caused by humans are also examined.

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Monday, the U.S. Coast Guard from Montauk confirmed the whale sighting, and took photos of the marine mammal, estimated to be 25 feet long. Besides taking photos and samples, the team Tuesday towed the carcass to Little Albert’s Landing, East Hampton, where biologists plan to perform a necropsy Wednesday, Bosworth said.