An aerial survey team of scientists from the New England Aquarium saw a pod of four orcas swimming 40 miles south of Nantucket during an aerial survey on Sunday – an unusual sight for New England waters.

Orla O’Brien, an associate research scientist who leads the aerial survey team at the aquarium’s Anderson Cabot Center for Ocean Life, said it was an exciting moment for herself and Katherine McKenna, the other researcher on the flight.

“We've been flying our aerial surveys for over a decade, and this is the first time that we've seen any killer whales,” Ms. O’Brien said.

The survey team flies several times each month to track populations of ocean wildlife.

Orcas are occasionally seen off the coast of New England, but sightings are unusual. — Courtesy of the New England Aquarium

The researchers consulted a team of orca experts who identified the animals as one adult male, one adult female and two juveniles. Though it’s possible the pod could be a family, Ms. O’Brien said she thinks it very unlikely the group was a set of parents and kids.

“Killer whales travel in family groups, so they could be related, but we don't know the relationship between the whales,” she said.

Sunday’s sighting is not unprecedented. There is a small population of orcas in the Northwest Atlantic, and around this time last year there was a sighting of two orcas a little further off the coast.

The only orca seen regularly in North Atlantic waters is “Old Thom,” a large male orca who is known to swim alone in the Gulf of Maine and the Bay of Fundy, the aquarium said. He was last spotted in Massachusetts waters in May 2022, off of Cape Cod.

Charles “Stormy” Mayo, director of the right whale ecology program at the Center for Coastal Studies in Provincetown, said orcas travel far to find food and that they are occasionally spotted in waters off the Massachusetts coast.

“It’s exciting, but I would not say it's rare,” Mr. Mayo said. “If people are out this time of year and into August, there'll be reports here and there of an orca. Not many — because they're spread out — but it does happen.”

Even if orcas off the New England aren’t uber rare, that didn’t dim the experience for Ms. O’Brien.

“It was an incredible experience to see four of them together, you know,” she said. “Even just one would have been amazing, but to see a whole group was really cool.”