A 20-foot humpback whale was found stranded on the sands of Long Island’s Robert Moses State Park this morning, according to a beachgoer who shared photos with Gothamist.

The whale is at least the 17th humpback beached along the Atlantic Coast this year, according to records from the National Oceanic and Atmospheric Administration — a troubling trend that federal oceanic researchers have dubbed an “unusual mortality event.” More than two dozen whales have washed ashore in New York and New Jersey in recent months, including a minke whale at Beach 29th Street in Far Rockaway, with some bearing evidence of collisions with boats or other vessels.

The cause of death for the whale found Friday was not immediately clear. The state's parks department said it did not have information about the beached whale. National Oceanic and Atmospheric Administration spokesperson Mendy Garron said the creature’s body was first spotted floating a mile south of Ocean Beach on Fire Island yesterday.

Garron said NOAA is working with the state parks department, the Atlantic Marine Conservation Society and the Department of Environmental Conservation “to secure the carcass and conduct a necropsy on site.”

A beachgoer named Arielle Hoffman shared photos of the whale, which she likened to the size of a “small school bus.”

“It was surreal,” she said. “It’s a very beautiful creature up close.”

Hoffman said that when she visited the beach this morning to take a walk, she encountered police and workers from the state parks department and saw a helicopter circling overhead. She said they told her the whale was first discovered at about 6 a.m.

Video from News 12 Long Island also shows water splashing on the whale’s body as it lays in the surf.

The recent spate of whale beachings remains a mystery, though it has driven conspiracy theories and concerns over the impact of offshore wind farms set to begin construction off the New Jersey coast.

But researchers say there is no evidence that the wind turbines or their installation are causing whales to be stranded on shore. NOAA told Gothamist earlier this year that more research is needed to determine the cause of the whale deaths.

Several experts have blamed warming waters that lead whales into unfamiliar territory.

“The culprit is a changing climate, and our inability societally to get it under control,” said Shawn LaTourette, the commissioner of the New Jersey Department of Environmental Protection, at a hearing on Thursday, according to WHYY. “Our oceans are getting warmer. They’re acidifying, we’re seeing changes in habitat.”