The Riverhead Foundation responded to two reports of whale carcasses on Tuesday, one on Fire Island and another in Westhampton Beach.

Over the next few days, marine experts will try to determine what caused the death of a 28-foot humpback whale, whose carcass was discovered washed up on a Fire Island beach, and a True's beaked whale, found in Westhampton at Pike's Beach, group spokeswoman Rachel Bosworth said.

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Suffolk County Police said the humpback whale carcass, a male juvenile, was found by a passerby in the surf line at Ocean Ridge, just east of Davis Park, about 8:30 p.m. Monday. The passerby called 911 to report the find.

Marine Bureau officers responded to the scene and then notified the Department of Environmental Conservation and the Riverhead Foundation, police said. The Riverhead Foundation responded at 12:30 p.m. Tuesday and will conduct a necropsy at 9:30 a.m. Wednesday.

Biologists found no external signs of trauma, Bosworth said, but they will have more information after the necropsy is complete.

It was not immediately clear who found the whale in Westhampton Beach. It was taken to the Riverhead Foundation's research facility in Riverhead at 1 p.m. Tuesday afternoon for a necropsy.

True's beaked whales are typically smaller, making them easier to transport than a humpback whale, Bosworth said.