Rare sighting of endangered blue whales

This is the print version of the story.

Two observers from the New England Aquarium looked out either side of a small twin-engine, four-seater airplane late last month and saw two endangered blue whales in Southern New England waters, just 15 miles south of the Island. It was a first for the aquarium.

The largest animal known to have lived, the blue whale is elusive. It has a body that can grow up to 90 feet and weigh more than 100,000 pounds, and its patterned blue-gray color appears light blue underwater. But with a small current Western North Atlantic population size between 400 and 600 individuals and a range over large swaths of ocean unseen by scientists, sightings, other than in Canadian feeding grounds, are uncommon. Yet on two separate surveys a day apart and 170 miles apart, aquarium scientists spotted three off the East Coast.

“Seeing blue whales outside of their Canadian feeding grounds is rare in the Atlantic,” Katherine McKenna, associate scientist in the aquarium’s Anderson Cabot Center and aboard both survey flights, said in a press release. “Finding them in two different areas of the ocean just 24 hours apart was a first for us.”

Scientists with the aquarium’s Anderson Cabot Center for Ocean Life do survey flights pretty frequently. On Feb. 27, they flew over the Northeast Canyons and Seamounts Marine National Monument, a previously protected and nearly 5,000-square mile area that the federal government recently reopened to commercial fishing. It was on this trip that they spotted a blue whale at the base of Lydonia Canyon.

Then, just a day later, the same team saw two other blue whales south of Martha’s Vineyard.

Orla O’Brien, a research scientist for the center who oversees all survey flights, said trips to the Monument, primarily used to document biodiversity and mark the assemblage of animals seen out there, are flown at 1,500 feet once a quarter. Pilots follow a set of track lines, like waypoints, as observers look for animals and mark each sighting down as a data point. In this latest survey, they saw whales and dolphins only, but in the summer and fall, they’ll sometimes spot oceanic rays and whale sharks. They saw three endangered fin whales, three endangered sperm whales, about 50 pilot whales, and hundreds of dolphins on that late February survey.

These sightings are significant in the Monument, O’Brien said. “It reminds us that there are a lot of animals out there that need a safe space, and so the best way to protect these animals is to give them spaces where they’re free of the risk of something like entanglement in fishing gear.”

The aquarium has spotted blue whales in the Monument only once before, in 2020. It’s also seen only one other blue whale off the coast of Maine, in 2023. Other partners have “sporadically” spotted blue whales in New England, the press release said. Migratory routes of blue whales aren’t well-known, but they have been spotted in the waters off Eastern Canada and the U.S.

O’Brien, who was on the Feb. 28 survey flight, was hesitant to say that sightings are rare, because really the animal is rare, but said that a lot has to go right for the scientists to see them. And between large stretches of coast and hundreds of miles of ocean offshore, sightings are uncommon.

And the aquarium has never spotted one on record in the Southern New England survey area, 170 miles from the Monument.

The surveys south of the Islands, done twice a month, are flown at 1,500 feet because of the several offshore wind projects right off the coast that host turbines just below the 1,000-foot threshold. The main priority is to document large whales and turtles; in the winter months, scientists mostly exclusively see North Atlantic right whales, but in the summer months, they can document large aggregations of humpback, fin, and minke whales, as well as different species of dolphins, leatherback sea turtles, and hammerhead and basking sharks. Weather, like fog and what’s colloquially known as scud, or low clouds, as well as wind speeds that can produce whitecaps, can really impact visibility on these surveys.

But on Feb. 28, O’Brien said, “the conditions were right, that the whale was up at the surface at the exact time the plane flew by.” That’s what makes the sighting really special or unusual, she said.

The whales were “decently close,” O’Brien said, to the offshore wind farms south of the Island. There are several offshore wind projects slated to be built south of the Island, though only one, South Fork Wind, is completed. Two under construction, Vineyard Wind 1 and Revolution Wind, are almost complete. O’Brien guessed that the whales were spotted between those two wind farms to be finished soon.

Anecdotally, O’Brien said she hasn’t seen “anything specifically that makes me concerned that the presence of the wind farms” has displaced the whales, though this is currently a topic of research for the aquarium as well as for other entities. She’s seen humpbacks and fin whales close to some of the installations in the summer months, and has seen a lot of right whales south of the farms.

“Pile-driving is something that could have the largest possibility of a displacement or disturbance in the moment,” O’Brien said, though there is research underway to test this theory. Pile-driving involves a vertical, column-like structure hammering into the seabed, and is used to install offshore wind turbines. And blue whales are one of the loudest animals on the planet; their sounds, used to communicate and navigate, can be heard by other whales up to 1,000 miles away.

O’Brien said, however, that there is also consideration that the pilings or turbines could disrupt water flow and affect, good or bad, whales’ prey. “We don’t know,” she said.

Developers of the Vineyard Wind 1 project entered an agreement in 2019 to protect right whales. It includes vessel speed restrictions and a construction timeline that favors the whales’ migratory patterns, especially for installation. This agreement was specifically made for the right whale, but consequently benefits other marine mammals.

Blue whales are found in all oceans but the Arctic Ocean, though their population was significantly reduced by commercial whaling in the 1900s. Michael Moore, emeritus research scholar at the Woods Hole Oceanographic Institution, said that as the largest animals in the world, blue whales were attractive and profitable targets in the whaling days.

But at between only 400 and 600 individuals today, the population still hasn’t recovered. Ship strikes, entanglement, and human-caused climate change have degraded the ecosystem and prevented a rebound. Moore calls this “whaling by mistake.”

O’Brien added the idea that maybe the whaling industry disrupted the ecosystem in a way that the same number of blue whales can’t be supported anymore.

Moore, who has a Ph.D. in the relationship between humans and marine animals, said he’s only seen five blue whales in his career, and one was a mortality after a 486-foot tanker struck the whale in March 1998 near Nova Scotia. (The skeleton of that 66-foot juvenile blue whale is now at the New Bedford Whaling Museum.)

Meanwhile, Moore, who wrote a book on right whales, said he’s had thousands of right whale sightings over the years, even though there are only about 380 individuals left of that species. That’s because he knows where they are.

“If you talk to any whale biologist who isn’t focusing on blue whales, their involvement with the animal is rare, because they are a very rare species,” he said.

Editor’s note: This story was updated to include more interviews as well as clarify that the 400 to 600 individual blue whales are part of the Western North Atlantic population.