BOSTON -- An unprecedented number of endangered northern right whales were feeding and lounging off the coast of Cape Cod, state and federal officials said.

Usually about 30 to 50 northern right whales are seen in Cape Cod Bay in the spring when animals return from their breeding grounds off Georgia and Florida and further south. This year, 50 to 100 whales were spotted in the bay, the Cape Cod Times reported.

The northern right whale is the world’s most endangered whale with only about 350 animals remaining. At this time of the year, a rich food supply of zooplankton draws the animals to Cape Cod Bay, which has been a federally designated critical habitat for the endangered whales. Each whale eats about 2,000 pounds of zooplankton daily.

"They seem to be oblivious to their surroundings. They are not really aware of us; they are not aware of other whales around them," said Dan McKiernan, of the Massachusetts Division of Marine Fisheries.

And that makes them highly vulnerable to ship strikes -- the leading cause of death and injury to right whales.

"If you are traveling in a boat at high speed, you stand a real chance of hitting them," said Stormy Mayo, of the Provincetown Center for Coastal Studies.

The state Division of Marine Fisheries imposed restrictions across the bay on vessels to protect the whales. Vessels are required to stay 500 yards from the whales, and fishermen cannot set or haul gear within 500 yards of the animals.