Last week, a group of North Atlantic right whales was spotted during an aerial survey running from south of Nantucket heading west to the waters south of Rhode Island. A large aggregation of right whales was spotted on both Friday, March 13, just southwest and southeast of Aquinnah, and one right whale was spotted on Monday, March 16, due south of Squibnocket.

Kelsey Stone was one of the spotters who saw the critically endangered whales south of the Vineyard last Friday.

“We had multiple sightings in the morning and later in the afternoon,” she said. Ms. Stone is an aerial observer and a research assistant for the New England Aquarium. She said she and the crew left the New Bedford airport before 10 a.m. and returned by 5 p.m. in a four seat, twin engine Cessna Skymaster. “It was a pretty calm day, low winds, calm seas and good visibility.”

Right whales swimming at the surface in a parallel track. — New England Aquarium taken under NOAA/NMFS permit No. 14233

While airborne, they noted at least 11 right whales from the air, along with a few dolphins, a gray seal and a minke whale. “For us, it was a pretty heavy whale day,” she said.

Right whales were first sighted here this year on Feb. 24, just south of Nantucket and to the east of Martha’s Vineyard. To protect these whales, authorities established a dynamic management area. Mariners were notified to proceed with extra caution when traversing the area. Vessels in the area are asked to have someone on the bow when passing through these waters and to move at a slow speed.

With last week’s additional sightings, a whole new zone of ocean stretching from south of Buzzards Bay to Nantucket was defined as a dynamic management area. That protection zone will remain in place through March 28.

North Atlantic right whales are the rarest of all large whale species, and among the most endangered of marine mammals in the world. As of this year there is an estimated population of 500, up from slightly over 300 two decades ago. They are coastal whales, spending much of their time not too far from shore. In pursuit of food, they migrate as far north as Nova Scotia and go as far south as Georgia to breed. During the summer they can be found in large numbers in Cape Cod Bay and off South Channel, east of Cape Cod. Death is often caused by ship strikes or when they are accidentally entangled in lobster and fish pots.

Right whales were first documented in this area in 2010. Charles (Stormy) Mayo of the Provincetown Coastal Studies Center, suggested that right whales may have been coming here unnoticed prior to then. Part of the discovery of right whale presence has been driven by proposals to open up areas of the ocean south of the Vineyard to wind farms, Mr. Mayo said.

“It is partly tied to increasing sensitivity about the causes for whale mortality, fishing gear and ship strikes,” he added. “We are becoming more sensitive when the state of Massachusetts and the federal government partner and take up looking. This is the result of us putting eyes and recorders up there.

Prior, there was no systematic method for extensive monitoring and recording.”

“We can be pretty sure that the aggregation of whales is related to plankton,” Mr. Mayo added.

For 40 years, the New England Aquarium has been a partner in the scientific monitoring of right whales. Tony LaCasse, a spokesman for the aquarium, said right whales are thought to spend much of December through February birthing in the waters off Georgia. “They begin to move back north after that. There are two major habitats in spring, the Great South Channel and in Cape Cod Bay, near Provincetown,” Mr. LaCasse said.

The science of understanding right whales is growing day by day, said Mr. Mayo, adding that perceptions of whale presence is changing, even for Cape Cod Bay, one of the most watched whale areas. Scientists have recently discovered that right whales also spend time in the fall and winter in Cape Cod Bay.

“In places less studied, like south of the Islands, we are still getting a vision of what is going on,” he said. “My sense is that this is an important area, important year after year. But it is not entirely clear when they are there. We are just getting a handle on what is going on in those waters.”

Christin Khan, a scientist with the National Oceanographic and Atmospheric Administration, said she is reaching out with others to put up posters and hand out literature to reach mariners. She has worked for a decade monitoring right whales and has been an aerial spotter. She said mariners need to be more aggressive about avoiding whales. When a ship is approaching, she said, “Right whales don’t move out of the way.”