Some rare right whales prefer Maine in winter
Area near Bar Harbor may be a mating ground, but mammals’ behavior puzzles scientists
For such large and well-studied animals, North Atlantic right whales are good at keeping secrets.
Until about seven years ago, no one knew that many of them congregate early each winter in Jordan Basin, which is about 60 miles south of Bar Harbor in the Gulf of Maine.
And now scientists think the area may be something they have been searching for: a mating ground for the endangered whales. With a population estimated at 440, they are among the planet’s rarest mammals, and scientists are eager to understand their mating habits.
Last fall, researchers from the New England Aquarium mounted several expeditions by boat to see the whales, which had been surveyed previously only by plane. They got tantalizing glimpses of unusual winter behavior.
In 2004, researchers for the National Oceanic and Atmospheric Administration who were surveying Jordan Basin by plane began seeing right whales frequently between November and January, sometimes more than 70 in a day. It surprised specialists in Boston to learn the whales are nearby in early winter.
“It was definitely an ‘Aha!’ moment,’’ said Amy Knowlton, a New England Aquarium scientist who has studied right whales since 1983. “It was like, ‘Wow, they are in our backyards; we just did not know it.’ ’’
Since learning about the seasonal gathering, New England Aquarium’s researchers had wanted to visit the whales, but the logistics were daunting. The Gulf of Maine is notorious for its winter winds and waves; cold temperatures and short days further complicate the fieldwork.
Last year, a senior scientist at the aquarium, Moira Brown, secured funding from the Canadian Wildlife Federation and the US Marine Mammal Commission, with support from Bar Harbor Whale Watch Co. In November and December, researchers made three trips to the area.
Brown said the crew did not see as many whales as they had hoped — they spotted about 20 in all — but they did get a snapshot of right whale behavior at a time and in a place rarely seen. The aquarium’s scientists know the right whales individually, by numbers referenced to a photo catalog, and they saw some familiar figures at Jordan Basin.
“We got really excited; the very first whale we saw was 2791, and she is due to get pregnant,’’ Brown said. “And soon after that we saw a male who has been in the population for over 30 years. So we thought, ‘All right, this is falling together.’ ’’
Brown said they saw mostly males, which would make sense, because researchers believe females can conceive only every three years, at best.
But they did not see whales mating, and the whales did not appear to be feeding. They did not seem to be doing much of anything.
“We figured they would probably be feeding, but certainly their surface behavior didn’t look like they were feeding; their movements were very random,’’ Brown said.
Philip Hamilton an aquarium research scientist, said he was surprised the whales seemed to be doing nothing in particular.
“I’ve never seen that in any habitat, and I’ve worked in all known right whale habitats,’’ he said. “They often weren’t lifting their tails; it did not seem that they were diving to depth. They weren’t logging consistently, which is where they just sort of rest.’’
“It seemed like they were waiting,’’ Hamilton speculated. “Waiting for a female to call.’’
Brown, too, wondered if the acoustics of the area play a role in the gathering.
“For example, if a big part of your social activity has to do with vocalizing and being heard . . . you might go to an area that really has really great properties for propagating females’ calls,’’ she said.
During aerial surveys in the area, Tim Cole a fisheries research biologist at the National Oceanic and Atmospheric Administration, has observed so-called surface active groups: females surrounded by males splashing energetically at the surface. This behavior is also seen in summer, when it would be out of sync with estimated gestation periods, but in winter it seems to be associated with mating.
Cole said females he has photographed in Jordan Basin have been seen with calves a year later.
Coordinating efforts, the researchers used Cole’s photographs, the New England Aquarium’s photo catalog, and tissue samples from calves, analyzed by a geneticist, to associate females that had given birth with males that had been nearby in Jordan Basin.
“That was sort of another piece of the puzzle, that this might be the mating ground,’’ Cole said. “Because they are there during the presumed conception period, if they have a 12- to 13-month gestation period, and there’s a high proportion of moms and dads there. So it all seemed to make sense.’’
Brown wants more conclusive evidence of mating, such as visual observation of mating behavior, plus a fecal sample, which would show hormone levels, followed by the whale’s giving birth a year later.
“The final piece de resistance would be a skin sample from the calf, so we could ID the father,’’ Brown said.
She is already trying to organize more trips to the area for late this year.
Over the past few decades, biologists have pieced together a map of right whale distribution that has allowed regulators to develop conservation measures to prevent the ship strikes and entanglements that kill right whales.
In summer, many whales spend time in the Bay of Fundy or nearby Roseway Basin, just south of Nova Scotia; the two habitats sometimes host three-quarters of the population. In late spring, many gather in the Great South Channel, between Nantucket and Georges Bank.
And since 1984 biologists have known that some females and calves winter off the coast of Florida and Georgia, where females go to give birth.
But the winter location of many right whales remains unknown, Brown said.
For example, at this time of year, she said, there are fewer than 100 near Florida and Georgia; perhaps six to two dozen are now in Cape Cod Bay, and a few might still be near Jordan Basin.
That leaves hundreds unaccounted for.
“Where are all the rest, and what are they doing?’’ Brown said.
“It is just sort of an endless series of mysteries. We poke away at it, and we get a little more information, which always leads to more questions.’’