On winter days when the weather is good, a research plane takes off from St. Simons, a barrier island in Georgia. Pilots from the National Oceanic and Atmospheric Administration fly straight lines out and back along Georgia's Atlantic coast, covering hundreds of miles of open ocean. Riding in the plane, surveyors are glued to the window scanning the water for North Atlantic right whales.

There are only about 450 of the big, rotund whales left on Earth. The whaling industry once decimated the species. While they've been protected for decades now, the endangered whales are still struggling, and this has been a terrible season for them.

The whales spend most of their time around New England and Canada, but starting in November pregnant whales and some others head south to the warmer water off the coast of Georgia and North Florida. This is where they spend the winter and begin to raise their calves.

But this year, no one saw any whales until the end of January. And most of the way through the calving season, there still aren't any calves.

So the aerial survey team keeps looking.

"On really nice days, you're looking out as far as possible, just for any disturbance at the surface," Melanie White says as she leans into the window of the plane, watching for whales. White is the Right Whale Conservation Project manager for Sea to Shore Alliance, the nonprofit that employs the surveyors.

She sees dolphins, sea turtles, rays and molas, which are big pancake-shaped animals also known as ocean sunfish. But rarely does the aerial survey team see a right whale. They've spotted just a handful this winter.

Last year the numbers were low, too. They've been trending down since 2011. But no calves at all is a low for recent years.

"This is the first time since I have worked with right whales that that has ever happened," said Barb Zoodsma, who has worked on right whales with NOAA since the early-1990s.

She says of the 450 or so right whales alive, fewer than 100 are breeding females.

"Ninety-four," she says. "That's not good. You don't have to be Einstein to figure out that's a bad situation."

Zoodsma says the females are dying young and they're having calves less often.

Climate change may be having an impact on their food.

On top of that, 17 right whales died last year. Several of those were hit by ships, or got caught in fishing gear. Another was found dead earlier this year, tangled in fishing gear off the coast of Virginia.

"The rope can cut through their bodies and keep them from being able to feed. It creates drag, and they basically just waste away," says Clay George, a wildlife biologist with the Georgia Department of Natural Resources.

George cuts the fishing gear off the whales when he can. He says more than 80 percent of the whales have scars from getting entangled at one point or another.

"The right whales are at a point where more are dying than are being born," George says. "That's just not sustainable long-term."

After hours searching from the air, Carolyn O'Connor from Sea to Shore Alliance finally spots something. "Bingo," she says.

The plane veers into a tight circle.

"I feel like there's a lot of whales here," White says.

There are five adults. One of them breaches. It slaps its tail. The whales are socializing. But still no calves.

O'Connor says it's exciting every time they see a whale, but "it's extremely disheartening and kind of scary to not have a calf yet this late in the season. It's not a good thing."

They'll keep looking for them, though, for another couple of weeks.

Copyright NPR 2019.