Amid all the depressing news about the declining state of the world’s oceans, here’s a genuine feel-good story: The critically endangered North Atlantic right whale population, once decimated by ship collisions, has rebounded to more than 500 individuals. That’s the highest level since researchers began studying the whale three decades ago.

News of the whales’ recovery was first reported Monday in the Yarmouth County Vanguard, a Nova Scotia newspaper. According to the article, the right whale population in Canada’s Bay of Fundy has added more than 300 calves since 1998.

Every summer and fall, a scientific survey is conducted to count and study the right whale population in the Bay, a critical habitat area.

Related Sea Shepherd to Deploy Drones to Stop Massive Whale Slaughter

The rebound was the result of a multiyear effort led by the Irving Oil company of Saint John, New Brunswick, in partnership with researchers, mariner organizations, environmental groups, the Canadian government, and the International Maritime Organization.

In 2003 the coalition successfully pushed for the rerouting of shipping traffic in the Bay of Fundy, which lies between New Brunswick and Nova Scotia and is an important feeding ground and nursery area for the North Atlantic right whale population.

It was the first time that shipping lanes were changed to protect an endangered species, according to the Vanguard. The rerouting reduced the risk of ships striking the whales by 90 percent, the Vanguard reported.

Irving Oil began working with the New England Aquarium in 1997 to protect the right whales, and has contributed more than $1 million for right whale research, conservation, and education.

The right whale, the rarest of large whales, is distinguished by its massive head and jaws, which comprise up to one-third of its body. Northern right whales are the most endangered whales on earth.

Right whales were almost hunted to extinction by whalers, who named the animal for its valuable amount of blubber, oil, and baleen, thus making it the “right” whale to hunt and kill, according to National Geographic. “Since our partnership began 17 years ago, there hasn't been a recorded ship-whale collision in the Bay of Fundy shipping lanes,” Paul Browning, chief executive of Irving Oil, told the Vanguard.

Regina Asmutis-Silvia, executive director of the North American office of Whale and Dolphin Conservation, acknowledged that the right whale population has increased dramatically. But “survivorship is still an issue,” she said in an email. “There has been a small recovery in the species, but 500 is still a tiny population.”

Equally concerning, Asmutis-Silvia noted, is the small number of new calves this year. Only 10 were born, about half the number as in 2013. One of the 10 did not survive.

“The bottom line is it’s okay to be cautiously optimistic and acknowledge that we are moving in the right direction, but I don’t think we are quite yet to the point where we can take our eye off the ball,” Asmutis-Silvia said. “It doesn’t take long to decimate a species, but it can take generations to help them recover. It’ll be a while before it’s time to pop the champagne cork.”