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Cape Cod sighting of rare whale raises concerns

Researchers at the Center for Coastal Studies observed a bowhead whale in Cape Cod Bay.

Center for Coastal Studies

Researchers at the Center for Coastal Studies observed a bowhead whale in Cape Cod Bay.

The bowhead whale that was spotted in 2012 off the coast of Cape Cod has been seen again in Cape Cod Bay — the farthest south that the species has ever been documented — prompting excitement and concern among researchers.

The Cape Cod presence of the bowhead whale, which normally inhabits the Arctic Ocean and far northern parts of the Atlantic and Pacific Oceans, raises profound questions about how whales are adapting to a changing environment in the world’s oceans.

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Researchers note there is not enough information yet to link the bowhead’s 1,000-mile southern sojourn with climate change. “It’s another piece of a puzzle,” said Corey Accardo, the flight coordinator for the Provincetown Center for Coastal Studies Right Whale Research program. “Being so far out of its natural range, and having it here twice leaves a lot of room for a lot more questions.”

Still, the bowhead’s foray is part of a larger picture of morphing whale behaviors.

Charles “Stormy” Mayo , director of the Center for Coastal Studies Right Whale Research program, said last year researchers documented, for the first time, a birth of a right whale in Cape Cod waters. Generally the whales go to Florida to give birth.

Right whales, which are related to bowheads, have been returning to Cape Cod — probably from Canadian waters — earlier than they have in years past, being spotted in mid-October rather than the usual January.

They also have been returning to Cape Cod in denser concentrations. It used to be that a quarter of the estimated 500 remaining North Atlantic right whales made their way to Cape Cod; now half the population returns. Mayo said one possible explanation is that changing currents in the Gulf of Maine are concentrating food in Cape Cod waters and drawing the whales.

“We are seeing a changing environment, one clearly different than it was,” he said.

The bowhead was first spied on April 9 in Cape Cod Bay and then days later near Race Point by researchers tracking right whales during a routine aerial survey.

Researchers didn’t know it was a bowhead when they saw it, but later identified it as such after examining photographs.

Researchers also were able to match the bowhead’s scars — one, a dot near its blowhole and another shaped like a crescent moon on its body — with scars that had been noted on the bowhead seen in 2012, and enabling them to say that it was the same animal. Bowheads often have numerous scars because they use their large skulls to push through sea ice to create breathing holes.

The whale was sighted again aerially on April 19, and then by boat, when researchers attempted and failed to get a genetic sampling.

A genetic sampling would provide clues about where the bowhead whale hails from. They are known to live north of Europe, between Canada and Greenland, in Hudson Bay area, in the Okhotsk Sea, and in the western Arctic, according to National Marine Mammal Laboratory. The whales migrate within these waters, alternating between summer feeding waters and wintering waters.

This bowhead, which measures about 40 feet long, has not been given a name or catalogue number yet since researchers are hoping to link it to a bowhead previously identified farther north.

In March 2012, the bowhead was observed engaging in a right whale courtship ritual in which a female calls to her male counterparts. Mayo said it is not clear if the bowhead is male or female.

Five months later, the bowhead was seen in the Bay of Fundy, on the northeast end of the Gulf of Maine, which is typically as far south as bowhead whales travel.

The bowhead was seen this year feeding with right whales. Like right whales, bowhead whales open their mouths and graze, often at the ocean’s surface. They filter out food, preferably zooplankton, which are microscopic, using long baleen plates.

Bowheads are protected under the Endangered Species Act and the Marine Mammal Protection Act.

Sarah Schweitzer can be reached at sarah.schweitzer@globe.com.

Correction: An earlier version of this story had the incorrect date for the second whale sighting.

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