EAST MORICHES, N.Y. – An ailing humpback whale that became grounded on a sandbar in a bay was euthanized on Wednesday, three days after rescuers first tried to set it free.

The death of the whale, which weighed between 15 and 20 tons and was about 33 feet long, angered some environmentalists and locals who had watched the rescue effort. One state senator called for a hearing into the failed rescue.

Officials with the Riverhead Foundation of Marine Research and Preservation and the National Oceanic and Atmospheric Administration insisted the best chance for the whale’s escape was hoping a high tide would allow it to free itself, but that never occurred.

They suggested it was likely the whale may have been ailing and that was the reason it became stranded in Moriches Bay, on eastern Long Island. The shallow bay has rarely been the site of whale visits.

Craig Harms, a professor of Aquatic Animal Medicine at the North Carolina State College of Aquatic Veterinary Medicine, who observed the whale on Wednesday, said attempts to haul the whale off the sandbar would have caused it further injury.

He and others assessed the whale’s condition and found it was thin, limp, weak and minimally responsive. They said it also had neurological abnormalities and possible infections. They sedated it and then euthanized it with injectable medications.

A necropsy is planned after officials remove the whale from the bay.

Humpback whales are common in the region. One recently has been seen swimming in the Hudson River.

Environmentalists said a stranded-whale scenario can happen again and when it does rescuers need to be ready for it.

“I’m not only sad, I’m angry,” said Adrienne Esposito, executive director of Citizens Campaign for the Environment. “Doing nothing is not an option. We are better than that.”

Deborah Fauquier, of the NOAA Fisheries Office of Protected Resources, said she would welcome discussions on improving the rescue response.