A humpback whale was discovered stuck on a sandbar in Moriches Bay.

The 25-foot whale became stuck in a very shallow part of the bay over the weekend. Officials believe that it's the same humpback that was seen in Moriches Bay more than a week ago.

Witnesses who gathered at the shore on Monday said the creature didn't move for a long time, then began flapping its tail in slow, exhaustive movements.

The Riverhead Foundation for Marine Research and Preservation says it went out to the animal Sunday by boat. But on its Facebook page the group said that "efforts to create wave action in hopes to move the whale off the sand bar were unsuccessful." The group later added that it's "disappointed in the recent turn of events."

Arthur Kopelman, who heads an organization that studies marine mammals, says there simply may not be any way to help.

"The options would be to either attempt to move it, and that can only be done when things are safe and if it's safe for the animal. The other is to leave it, and I guess the third option that would be considered at this point is euthanasia," Kopelman says.

Onlookers held out hope that the added water during high tide might lift the whale off the sandbar and carry it to safety. But the animal has been there since Sunday afternoon and has already experienced several high tide cycles. At one point, two residents from the area went out in a small boat to see if they could help, but to no avail.

"It'd be nice to see if it gets off, but I don't think anyone's realistically optimistic," Kopelman says.