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The population of critically endangered North Atlantic right whales, as shown in this undated handout photo provided by the New England Aquarium in Boston, appears to be levelling off after years of discouraging declines, according to new data released today by an international team of marine scientists.HO/The Canadian Press

The decline in the number of North Atlantic right whales shows signs of levelling off, raising hopes that conservation measures are helping to protect the animals from being struck by ships or tangled up in fishing gear in the Gulf of St. Lawrence.

The North Atlantic Right Whale Consortium, a conservation group, said on Monday that its population estimate for 2022 was 356 animals, and that its 2021 number had been recalculated at 364, up from an original estimate of 340. (The consortium releases population estimates annually.)

“This is showing that the decline is slowing – and that, believe it or not, builds cautious optimism,” said Moira Brown, senior scientist with the Canadian Whale Institute.

The North Atlantic right whale is one of the world’s most endangered large whale species. They live primarily in Atlantic coastal waters and migrate to calving grounds off South Carolina, Georgia and Florida. While they once numbered in the thousands, by the 1890s they’d been hunted to near extinction, and since 1935 they’ve been protected from whaling. The total population in 2010, including all age classes, was estimated at 468 individuals, according to a Canadian government endangered species report.

Researchers started seeing right whales in greater numbers in the Gulf of St. Lawrence from around 2010, Dr. Brown said. As water temperatures increased in the Gulf of Maine, the plankton that the right whales used to depend on in that area disappeared, Dr. Brown said, forcing them to search elsewhere for food.

The whales found that food in the Gulf of St. Lawrence – along with fishing gear and speeding ships.

In 2017, the U.S.-based National Oceanic and Atmospheric Administration declared an unusual mortality event for the North Atlantic right whale after determining that dead, injured and sick whales in Canada and the U.S. accounted for more than 20 per cent of the population, with deaths outpacing births. That UME is ongoing.

Twenty-one right whale deaths were documented in Canada between 2017 and 2019, according to Oceana Canada, a registered charity focused on ocean conservation.

With the spike in deaths, authorities in Canada and the U.S. implemented measures intended to reduce threats to the whales, including speed limits for ships. But researchers say more needs to be done.

A flat trend indicates animals are still being killed at the same rate, or faster, than they’re being born, said Heather Pettis, a research scientist in the Anderson Cabot Center for Ocean Life at the New England Aquarium and the executive administrator of the North Atlantic Right Whale Consortium.

“We know that elevated levels of stress affect health and reproduction,” Ms. Pettis said, adding that female whales are giving birth to fewer calves, at an older age, and that research shows whales are smaller than they were in the 1980s.

“If we can reduce the impact of entanglement and vessel strikes, that will give the animals a bit of a reprieve to get as healthy as they can.”

Eleven calves were born this past calving season, the consortium said in its Monday release, compared with 18 in 2021 and 15 in 2022.

Since 2017, Transport Canada has been implementing speed limits and restricted areas to protect right whales in the Gulf of St. Lawrence. In 2020, it also put in place a trial voluntary slowdown in the Cabot Strait, a gap between Newfoundland and Cape Breton that right whales travel through in the spring and fall. The trial was subsequently extended and remains in place this year.

Oceana Canada has called for the slowdown to be mandatory, saying in a 2022 report that satellite data showed most vessels travelling through the strait did not comply with the 10-knot voluntary limit.

Dr. Brown said the critical corridor is a good candidate for mandatory speed measures because right whales go through it in mother-and-calf pairs or on their own, which means they are harder to detect than when they gather in feeding or calving grounds.

Right whales may still be suffering the impact of the shift to the Gulf of St. Lawrence, she said, but she is optimistic about their future if conservation measures continue.

“I just think these animals are so tough. We hunted them for decades, we didn’t wipe them out. They make their living in a very urbanized ocean – and with the efforts of those operating on the water, they’re still there. With a little more of a chance, I think they can make a comeback.”

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