Porpoise seen swimming off shore in Dorchester

It’s not every day you see a porpoise swimming in Dorchester.

But that’s exactly what happened last Friday, and Paul Moore was there to get it on video. The Savin Hill resident noticed a dorsal fin cutting through the water just a few yards away from the shore, near the Dorchester Yacht Club.

Moments later, the fin surfaced again, and then dipped back into the water, and surfaced again as it gracefully made its way through the harbor, with the colorful National Grid gas tank and the Southeast Expressway in the background.

“It was quite a sight,” said Moore, 55.

Officials from the New England Aquarium identified the animal as a harbor porpoise and said it was the first official sighting in the Boston area for this winter season.

Harbor porpoises have been known to swim along the waterfronts of East Boston and Winthrop, and even all the way up the Mystic River to Somerville and up Chelsea Creek. In 2017, a harbor porpoise was seen swimming in the harbor near Fort Point, and last year a pregnant harbor porpoise became stranded and died near the UMass Boston campus, aquarium officials said.

Harbor porpoises are the smallest of the dolphin species in New England and grow up to measure between 4.5 to 6 feet long as adults, aquarium officials said.

Since the successful cleanup of Boston Harbor, they’ve become regular visitors from mid-winter to early spring. They usually leave the area and head to the Gulf of Maine by late April or May, aquarium officials said.

Connie Merigo, the head of the Aquarium’s Marine Animal Rescue Team, said the porpoise in Moore’s video looked to be in good shape.

“The porpoise appears to be behaving normally and does not appear to be in any distress,” she said in a statement. “The porpoise is close to shore, which for any other cetacean (whale, or dolphin), would be of concern, however harbor porpoise[s] got their name because they are comfortable in shallow areas such as bays and harbors. This animal appears to be swimming calmly, taking good breaths and is swimming parallel to the beach, all of which are good signs.”

Merigo said this is the time of year that porpoises show up along our coast because the water is cold enough.

“We see them in Boston Harbor off the back of the Aquarium all the time,” she said. “When I first started my career at the Aquarium 25 years ago, we almost never saw porpoise or seals in the harbor. Now we see them all the time and dolphins as well.”