In this March 28, 2018, file photo, a North Atlantic right whale feeds on the surface of Cape Cod Bay off the coast of Plymouth, Massachusetts. Credit: Michael Dwyer / AP

All in all, it’s been so far so good this year.

No dead right whales have been spotted. Fifteen calves were born — the second-largest number since 2015. And observers were impressed by the saga of one whale, a mother who, injured and entangled in fishing gear, managed to escort her calf a thousand miles up the coast

And researchers continue to keep tabs on how the species is doing.

Michael Moore, a senior scientist at the Woods Hole Oceanographic Institution, recorded a recent encounter with a right whale off Massachusetts.

“Now the swells have dropped down and it’s a couple hours before sunset and now the whale’s leveling out a little bit, it just blew. You can see a little bit more of its back,” he said in the recording.

“It’s a small whale, maybe 30 feet long. A year, maybe two years old,” he said. “A little whale lice on it. And it’s head is sticking out of the water at a fairly sharp angle, and you can see the rack of baleen hanging out of the roof of the mouth.”

Moore is one of the researchers who documented the activities of some 260 right whales that showed up in Cape Cod Bay this winter — that’s about three quarters of the estimated total world population of around 335.

“Cape Cod Bay has become a remarkably popular place for right whales. So obviously, they’re not going elsewhere when we’re there. And is that because Cape Cod Bay is so special? Or is it because the other places have got worse? And we just don’t know yet. So that’s … one of the challenges,” he said.

The whales have been arriving in Massachusetts waters earlier each year, and staying later, feeding on plumes of tiny crustaceans called copepods that may be gaining abundance there. It’s one element in an emerging shift from the whales’ longtime migratory patterns.

They left the Cape in mid-May. Many headed east and north, with two sighted off New Hampshire late last month, and then dozens of sightings in Canadian waters.

It’s unknown whether they are venturing near Maine at all: While there’s been a smattering of sightings and detections relatively close to Maine’s coast in recent years, there is no organized real-time surveillance in the area right now.

“So whales are looking in Canada, for food, when they used to be looking in the Gulf of Maine,” said Nick Record, a senior scientist at the Bigelow Laboratory for Ocean Sciences in East Boothbay.

Until just five years ago, the whales dependably summered in the Bay of Fundy, right at Maine’s maritime border with Canada, he said.

But in recent summers, few have been sighted there. Instead, observers have identified as many as 185 right whales further north in the Gulf of St. Lawrence. Record pointed out, though, that does still leave almost half of the population unaccounted for.

“We used to see almost all of them, not quite all of them, in the Bay of Fundy, eastern Gulf of Maine, places like that. And we just don’t know where, if anywhere, they’ve landed yet. Maybe they’re still looking around for their next Bay of Fundy,” Record said.

Since 2017, a growing body of research by Record and others shows that climate-driven warming and changing currents are suppressing the abundance of the whales’ preferred forage in the Gulf of Maine, including the Bay of Fundy.

That may be propelling a long-term shift by the whales to cooler, more northerly waters off Canada. But in the short term, he said, it’s hard to tell whether they might head back closer to Maine’s coast. Just last month, one of Maine’s copepod experts found the nutritious crustacean the whales like to eat at a high density off the midcoast.

“The year to year variability is so much higher than it used to be. I’m guessing that the whales are responding to that too, and that’s why it’s so hard to find where they are because they’re going to different places, the ocean hasn’t settled into a new pattern yet, so they haven’t settled into a new pattern,” Record said.

And for the whales, even short-term habitat shifts can lead them more quickly down the road to extinction, particularly when shipping companies, fishermen and regulators are unprepared for their arrival. Over the last five years, 21 were found dead in Canadian waters, killed by ship strikes, entanglements in fishing gear and undetermined causes. Thirteen deaths were found in U.S. waters over the same period.

And the roster of whales unobserved long enough that scientists believe they died unobserved grew by the dozens. In just a decade their numbers have dropped by a third.

Canadian regulators are responding to the whales’ arrival this year with large-scale closures of fishing areas to snow crab traps that depend on vertical rope. And it’s the whales’ ability to range around, to find new feeding grounds, that is giving scientists and advocates hope.

“Well, I think right whales are figuring it out,” said Amy Knowlton, a researcher at the New England Aquarium.

She noted that whales have been around many millions of years longer than humans.

So they have a demonstrated ability to withstand epochal changes in climate, and might adapt to the rapid, volatile changes underway now.

“They’ve  shown they’re able to adapt in climate change times and you know, their major shift to the Gulf of St. Lawrence is an indicator of that,” Knowlton said. “So they seem to be able to find what they need.”

If, Knowlton said, human-caused injuries and mortalities can be stopped.

Knowlton and colleagues recently documented a long-term decline in the whale’s growth rates, and the fertility of female whales — developments the scientists attribute to stress and other difficulties caused by entanglement injuries.

It’s too early to measure whether closures of lobstering grounds and gear rules enacted off New England this year are averting new entanglements, and there are arguments on all sides about their effectiveness. But when Knowlton joined researcher Michael Moore on Cape Cod Bay this spring, she liked what she saw.

“The whales looked pretty good. Maybe there was one whale that looked in poor health. Otherwise I thought they looked pretty robust, which was encouraging to see. And I don’t remember seeing evidence of new injuries or entanglement scars. Plenty of them have them, but I didn’t see what looked like fresh wounds,” Knowlton said.

Still Knowlton, along with most whale scientists, conservationists and federal regulators, said the species will not survive without more protections.

And she noted that one 14-year-old female whale called Sundog that has suffered chronic entanglements was sighted off Massachusetts in March, free of any fishing gear.

But late last month, she was spotted off Canada’s Gaspe peninsula, entangled once more. Sundog is one of fewer than 100 female North Atlantic right whales of reproductive age.

This article appears through a media partnership with Maine Public.