New England Aquarium researchers spotted something unusual Sunday afternoon during an aerial survey – a group of 4 orcas who were swimming just 40 miles south of her Nantucket Massachusetts.

According to a report by CNN, killer whales are most commonly seen in areas surrounding the edge of the Arctic and Caribbean ice, according to the National Oceanic and Atmospheric Administration. The last orca sighting in Massachusetts waters was in May 2022.

Katherine McKenna, a research assistant at the New England Aquarium in Boston, was the first to notice the group.

“At first I could only see two splashes in front of the plane,” McKenna said in a news release. “As we circled the area, two whales surfaced too quickly for us to know exactly what they were. Then we got a good picture and could see the telltale coloration before the large dorsal fins came to the surface.”

Scientists at the aquarium use regular aerial surveys to monitor changes in marine animal populations and look for trends.

Orla O’Brien, research associate who leads the aerial survey team for the Anderson Cabot Center for Ocean Life Aquarium, noted in the release that the team’s sighting was “special” because the orca population in the waters of the western North Atlantic is very small . . During Sunday’s search, investigators confirmed that the group they saw included one adult male, one adult female and two juveniles.

Another atypical orca sighting – with particularly large numbers of orcas – also occurred this past weekend in coastal waters on the other side of the United States, in California’s Monterey Bay.

A group of about 30 orcas spotted there Sunday consisted of 11 families, including six orcas from Canada, according to Nancy Black, a marine biologist with Monterey Bay Whale Watch and director of the nonprofit California Killer Whale Project.

Whales come together to socialize and form relationships with other families to hunt more effectively, Black said.

“This was the best sight I’ve seen in my 35 years of orca research,” Black told CNN. “Simply excellent.”

There was no clear explanation for why there were so many sightings Sunday, according to Black, who said there have been more sightings in Monterey Bay in the past two weeks.