About 20 to 30 dolphins remained stranded in a shallow cove off Long Island after rescuers failed to herd the sea mammals out into deeper waters, raising fears that they could die from hunger.

The animals could also be facing a cold snap as forecasters are expecting in the coming days.

Dozens of dolphins became stranded last week in the Northwest Harbor cove, attracting spectators to see the animals and marine biologists who feared for their safety. Five dolphins have already died. Rescuers said they may be dying from stress or hunger, but a New York State Department of Environmental Conservation official said a necropsy result on the causes of death was not yet available.

"They're stressed; they haven't been eating," said Charles Bowman, president of the Riverhead Foundation for Marine Research and Preservation, speaking to Newsday for its Monday edition.

It is unusual for the dolphins to be in the cover, marine biologists said, explaining that warm waters and an abundance of fish-bait may have been what drew the sea mammals to the area.

On Sunday, rescuers attempted to herd them out of the cove using devices, called pingers, which emit a high-frequency sound, to direct the animals to safety. But the animals often began to panic and retreated back into the cove.