By Orla O’Brien
New England Aquarium researchers spotted two blue whales, the largest animals on Earth, during their inaugural winter aerial survey of the Northeast Canyons and Seamounts National Marine Monument that also recorded 17 other large whales.
Among the other highlights of the February 9, 2020, aerial survey were the sightings of several species of large whales, including fin, humpback, pilot, sei, Sowerby’s beaked, and sperm whales.
Preparations for any aerial survey of the Northeast Cantons and Seamounts National Marine Monument are always intense. At 130 miles southeast of Cape Cod, the monument features weather conditions that can be unpredictable and hard to forecast. Good weather conditions are paramount because marine animals, especially dolphins and small whales, are almost impossible to see when surface winds are more than 10 knots (11.5 mph).
The New England Aquarium aerial survey team had extra pressure riding on this survey. After almost three years of conducting surveys in this unique offshore area, we still had not flown a survey in the winter months. With a large storm system moving through New England over the weekend that included 70-knot gusts on Cape Cod, it might have seemed unlikely that we would get adequate survey conditions for Sunday, February 9. However, we were counting on the storm to leave light winds in its wake, and our patience paid off!
The sun rose over clear skies Sunday morning, and the air was cold and dry, a good sign of a high pressure system moving into the area. The team met early at Plymouth Municipal Airport. After a thorough safety briefing by Avwatch pilots Chris Kluckhuhn and Jeremy Prignano, we all piled into the survey plane and took off at 8:58 a.m.
Observers Amy Warren, left, and Orla O’Brien pose in front of the Cessna Skymaster survey plane.
On the way out to the monument, team members always discuss what we hope to see. Observer Amy Warren was hoping to see a fin whale, which she had only seen from a boat. I was just hoping we would see something. We are used to being surprised with unique sightings at the monument, but this was the winter. Would there be anything out there?
After a transit out to the survey area that was just under one hour and 10 minutes, the plane descended to 1,000 feet and slowed to 100 knots. We turned onto our first trackline and within the first few minutes we had a sighting of a group of 50 offshore bottlenose dolphins (Tursiops truncatus)!
A few minutes later we spotted a sei whale (Balaenoptera borealis). It was our first time spotting this species, a smaller relative of fin whales, in the monument. Shortly after the sei whale, we saw a humpback whale (Megaptera novaeangliae). We were only a quarter of the way into the first trackline and were off to a great start.
The real surprise of the day came halfway down our first trackline. We spotted a whale a mile off the trackline and flew over to take photos and identify the species. As we passed over the whale, we noticed how large it was. Then we realized that’s because it was a blue whale (Balaenoptera musculus)! Blue whales are the largest whales in the ocean, and, in fact, the largest animal on the planet. Blue whales can grow to 100 feet long and weigh up to 140 U.S. tons. This sighting was directly on top of Oceanographer Canyon. At 4,000 feet deep, it’s the deepest canyon in the monument.
The survey continued with a few more sightings of bottlenose dolphins and a pod of 10 pilot whales (Globicephala sp.) at the beginning of the second trackline, which was in deep waters past the continental shelf. Just after the plane crossed back onto the shelf, we had a sighting of a single Sowerby’s beaked whale (Mesoplodon bidens). We have seen this species of beaked whale, identified by its distinctively long rostrum, several times on our surveys of the marine monument. The canyons are a perfect habitat for Sowerby’s beaked whales because they are deep diving whales that feed on deep-sea fish and squid.
Continuing on the second trackline, we spotted a group of 20 striped dolphins (Stenella coeruleoalba). Striped dolphins are the same dark gray as bottlenose dolphins, and it can be easy to confuse them from 1,000 feet in the air. However, a review of our photographs clearly showed the distinct pale stripe, or “scarf,” going from the middle of the body past the dorsal fin. We also noticed something else in the photos: striped dolphin calves!
Throughout the survey, the team saw two groups of striped dolphins, and both of these groups had calves with them. We have grown accustomed to seeing calves in groups of small odontocetes, or toothed whales, but in the winter, when the calves are older and larger, they can be a little more difficult to spot. One fail-safe way to find calves is to look for two animals traveling together, one in the “calf position.” Dolphin calves travel right next to their mothers as a way to draft off them and save energy.
While flying between the third and fourth tracklines, we spotted a pair of sperm whales resting at the surface. Sperm whales, like the beaked whales, are deep divers that feed on squid they find in the canyons. They can dive for up to 45 minutes, so our survey plane probably flies over many more sperm whales than we see. In between long dives, they rest at the surface.
At the end of our fourth trackline, we saw two small pods of common dolphins (Delphinus delphis), and Amy got her desired aerial view of two fin whales. At the very end of this trackline, we saw our second blue whale of the day! By this time, the winds had calmed to a Beaufort Sea State 2 (4 to 6 knots of wind) and the sun was directly overhead, making the conditions perfect for photos.
At almost 20 nautical miles away from our sighting of the first blue whale, we knew this must be a different animal, but we were able to confirm that it was a different individual with our photos. Blue whales can be individually identified by their dorsal fin, as well as the mottling pattern on their backs. Richard Sears, President of the Mingan Island Cetacean Study in Quebec, was able to match this blue whale to an adult female in their catalog: B353. This whale has a sighting history dating back to 2000, making it at least 20 years old and likely older than that. She has been seen previously in the St. Lawrence Estuary, the Gulf of St. Lawrence, and the Gulf of Maine.
It’s always fun to see rare or new species, but sometimes our favorite moments occur with more familiar animals. At the top of our fifth trackline, we saw the blow of a whale. By the time we flew over, the whale had disappeared beneath the water. However, we noticed that there was a small group of common dolphins in the same area. Having spent many seasons leading whale watches in New England, both Amy and I knew that dolphins often remain at the surface in an area where a large whale is on a deeper dive. Trusting our instincts, we waited, and sure enough several fin whales came back to the surface. We watched in amusement as the dolphins cavorted around the whales, sometimes riding in the “bow wave” in front of the whale’s rostrum.
We finished off the survey flying our last trackline over Lydonia Canyon and found more Sowerby’s beaked whales, common dolphins, fin whales, and several trawls of fixed fishing gear. We transited home along the northern edge of the survey area, where we were pleased to see blue whale #353 one last time before picking up speed and heading back to Plymouth. We landed at 3:02 p.m., packing 322 whales and dolphins into just six hours.
Every trip to the marine monument yields something different and exciting. We have flown eight surveys in the past three years, and there is still so much to learn. We were intensely curious about what would be out there in the winter and were thrilled with our results. However, this survey leads to as many questions as it answers.
We were struck by how many large baleen whales we saw, compared to the species we are used to seeing (small squid-eating odontocetes). We were also struck by the lack of what had previously been a staple species: the Risso’s dolphin (Grampus griseus). To find out whether these differences represent a true seasonal pattern or were simply driven by some temporary change in oceanographic conditions, we will have to fly back out to the monument. Personally, I can’t wait.
Our surveys are made possible due to the support of Natural Resources Defense Council, Conservation Law Foundation, and National Ocean Protection Coalition.
The pilots and observers show their big blue whale smiles!