It’s a big ocean, and there are only 524 known North Atlantic right whales still swimming in it. So when wildlife researchers found more than 20 percent of the worldwide population in Cape Cod Bay this week, they knew that something special was happening.
An aerial survey by the Center for Coastal Studies on Sunday spotted 112 right whales in the bay, the largest number recorded there in a single day.
Charles “Stormy” Mayo, director of right whale habitat studies at the center, said the whales often gather in the bay at this time of year, but the swelling numbers are all the more remarkable given that the global population of the endangered species appears to be declining.
“It’s quite a remarkable sighting. These are animals that are a lot rarer than a lot of those that you and I watch on TV,” he said, noting that many of the right whales spotted this week would have been visible from shore. “Lo and behold, every winter and spring, they come to this bay.”
Mayo said researchers are trying to find out why the right whales have been gathering off of Cape Cod, but it has something to do with the availability of food. The whales eat tiny zooplankton that they strain from the water.
“Basically, this is their restaurant in some respects,” he said. But he cautioned people not to assume that the large number of right whales in New England is representative of the trends in the larger population.
The animals, whose numbers were decimated by whaling, continue to be in danger of further population losses. Making the circumstances of the visit more momentous, Mayo said, is that two of the three known calves born this year were spotted in Cape Cod Bay.
The conservancy warned boaters to be extremely careful in the bay while the whales are around. Mayo said they often swim long distances just below the surface — at a depth that makes them vulnerable to propellers.
It’s illegal for watercraft or light aircraft to come withing 1,500 feet of a North Atlantic right whale without a research permit.
The conservancy did its survey Sunday with observations from both air and sea. The previous record for sightings in the bay was 96 in 2014, Mayo said.
North Atlantic right whales range from Florida to Canada, around Iceland, and from Portugal to Scandinavia. They will probably leave the bay soon, Mayo said. He has seen them remain into May, but he expects them to go sooner this year.
He encouraged people to take in the rare sight from land while they have the chance.Andy Rosen can be reached at email@example.com. Follow him on Twitter at @andyrosen.