Scientists who study the endangered North Atlantic right whale estimate that the species will be doomed to extinction by 2040 if humans don’t make substantive changes to protect them.

The dire prediction, delivered at an annual meeting of experts on the species in Halifax, Nova Scotia, comes amid the worst die-off researchers have ever recorded. Sixteen right whales have been found dead this summer and fall – the most recent on Monday off Cape Cod – a catastrophic development for a species with an estimated worldwide population of just 450.

“At the rate we are killing them, we will have wiped out all existing breeding females in 23 years. That’s a very short period of time,” said Mark Baumgartner, the Woods Hole Oceanographic Institution scientist who chairs the international study group that convenes the annual meeting, the North Atlantic Right Whale Consortium.

The central focus: first making the ropes used in lobster and crab fisheries less deadly for the whales, and ultimately developing ropeless trap technologies.

“There’s a very real sense of urgency that we need to do something,” Baumgartner added speaking via telephone from Halifax. “We don’t have decades to do it. We have years.”

The whales, many of which traditionally came to the waters off Lubec and Grand Manan Island, New Brunswick, in late summer to feed, began turning up dead in early June. Canadian authorities have documented 12 dead right whales in the Gulf of St. Lawrence, while another four have been found in the waters around Cape Cod. The deaths recorded to date represent more than 3 percent of the species’ total population of 450. Scientists have estimated that before the whaling era there may have been more than 21,000.

Humans appear to have caused many of the deaths this year of the slow-moving whales. Conclusive necropsy results have been issued for just five of the whales found off Canada, showing one had become entangled in snow-crab fishing gear and four were apparently struck by ships. An additional whale showed signs of an “acute” death, also suggestive of a ship strike, according to a report by the Fisheries and Oceans Canada.

A necropsy performed on one of the four carcasses found around Cape Cod also determined it died of a blunt force trauma. Two other bodies were too decomposed to make a judgment and the fourth – found Monday – is still being examined.

CHANGES IN FOOD SOURCES

The bulk of the deaths have taken place in an area the whales haven’t previously frequented, the Gulf of St. Lawrence, the vast body of water bounded by New Brunswick, Nova Scotia, Newfoundland, Labrador and eastern Quebec. Because they weren’t anticipated in the area, ships were not subject to speed restrictions to reduce the possibility of collisions, though Canadian authorities have since imposed new rules in the area.

Why so many of the whales are there is a mystery. The prevailing hypothesis among scientists is that they came there because they have been unable to find sufficient food in the Gulf of Maine and Bay of Fundy, where their numbers have dwindled in recent years during the summer feeding season.

The whales – which can live to be at least 70 years old – forage on clouds of their favored prey, the copepod Calanus finmarchicus, a tiny flealike creature they can scoop up by the millions with their sievelike baleen. This is what traditionally brought them to the waters off Lubec and Grand Manan Island or the Roseway Bank further offshore in the Gulf of Maine.

But the Gulf of Maine is warming faster than any other part of the world ocean, save a stretch of ocean current off northern Japan, raising concerns among marine scientists that Calanus – which also sustains herring and other forage fish at the bottom of the food chain – might have a harder time living here. Catherine Johnson, who studies the tiny creatures at the Bedford Institute for Oceanography outside Halifax, has found their numbers have been declining on the Canadian side of the Gulf of Maine and off the southern coast of Nova Scotia, where currents carry the cold-water creatures into the gulf.

“We know the Gulf of Maine is warming very quickly so the hypothesis is that they are moving for food, but there isn’t yet enough research to tie that all together,” Baumgartner said.

With Canadian authorities already reducing ship speeds, researchers say the most important thing people can do is to reduce the risk of the whales getting entangled in fishing gear, especially the ropes that anchor lobster and snow-crab buoys to the traps on the bottom.

THE RISKS OF ENTANGLEMENTS

Amy Knowlton of the New England Aquarium told conference participants Sunday that 85 percent of all right whales have been entangled at some point in their lives, and half of them multiple times. The numbers are increasing, she said, because the ropes fishermen use have gotten much stronger since the late 1990s due to technological improvements, making them much harder for the whales to break free from.

“The ropes are too strong for the whales to successfully live among these ropes,” Knowlton said, according to the CBC. “So we’re trying to change the rope that’s out there or eliminate it entirely.

Even when whales escape, entanglements can have an effect on the birth-death ratio of the species. “We’ve seen that females that get entangled in fishing gear are less likely to have calves even after the gear is removed,” Baumgartner said. “It’s simple math: We’re killing them faster than they can reproduce.”

He said this year there had been just five live births, compared to 16 documented deaths. The situation is likely worse, he added, because research has shown that humans only find about a fifth of the bodies of the whales that die in a given year.

In the short term, the researchers are calling for fishermen to return to the types of ropes they used in the early 1990s, which had a lower breaking strength, but still supported viable fisheries. In the longer term, Baumgartner said, the hope is that fishermen will be able to introduce rope-less traps that automatically deploy buoys that shoot to the surface when prompted with an acoustic trigger.

Engineers at the Woods Hole Oceanographic Institution have been working with Massachusetts lobstermen to test such devices. “Our system is to try to store the vertical line on the seafloor – keeping the lines out of the way of large swimming animals – until the fishing vessel crew releases it and is on site and ready to haul it in,” one of the engineers, Jim Partan, told the institution’s in-house magazine.

In any case, he said, the time for action is now. “The time for study is over, it’s time to do something about the problem,” he said. “I don’t want to study the right whales until they go extinct.”

Colin Woodard can be contacted at:

[email protected]

Send questions/comments to the editors.