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To a non-Washington story now. Humpback whales have made a remarkable comeback. After being hunted close to extinction, their numbers have rebounded in the Pacific Ocean. But a new study finds the whales are now facing a different threat. Lauren Sommer from NPR's Climate Desk reports.
LAUREN SOMMER, BYLINE: For 30 years, Ted Cheeseman worked as a naturalist, guiding trips on boats around Antarctica. That meant looking for whales, which wasn't easy in the early 1990s.
TED CHEESEMAN: We saw very, very, very few whales. And in the 2000s we started seeing more. 2010s we started seeing quite a few whales.
SOMMER: The whales were slowly recovering from industrial whaling, which lasted into the 1960s.
CHEESEMAN: Photographing these whales, seeing like, hey, you know, I'm essentially collecting data that could be valuable to science.
SOMMER: Photos are key for scientists to identify and count whales. The tails of humpbacks each have their own unique pattern.
CHEESEMAN: And so you can look at them like we look at each other and recognize each other's faces.
SOMMER: Well, scientists typically do that photo by photo, matching the tails in a painstaking process. But Cheeseman figured that artificial intelligence could do that more quickly. He started Happy Whale and pulled together around 200,000 images of humpback whales. Many were from scientists, but others were from whale-watching groups since anyone can upload a photo to find the exact whale they're looking at.
CHEESEMAN: In the North Pacific, we have identified almost every living whale. We were just doing this as a study of the population. We didn't expect to see a major impact of climate.
SOMMER: But that's what he and colleagues found for one group of whales. Some humpbacks feed in Alaska in the summer and then spend winters in Hawaii. That group is declined 34% since 2013, a big setback. It happened when a marine heat wave hit known as The Blob.
CHEESEMAN: This very large body of warm water sat at the surface stretching from Alaska to the coast to California.
SOMMER: The warm water changed the entire food web, including the food humpbacks rely on. Marine heat waves are expected to get worse as the climate gets hotter. John Calambokidis is a whale biologist at Cascadia Research and a co-author on the study with Cheeseman.
JOHN CALAMBOKIDIS: I think the scary part of some of the changes we've seen in ocean conditions is the speed at which they're occurring. And that would put kind of long-lived, slow-reproducing species like humpback whales and other large whales has more vulnerable.
SOMMER: Calambokidis says the reason they could spot this decline is because humpbacks have recovered so well. For other whales, it's harder to see the impacts.
CALAMBOKIDIS: I think it is important to think about what consequences - could that be happening to these rare species, where it's really hard to get data.
SOMMER: But he's hopeful that new image recognition technology will help marine biologists spot these impacts faster in all whale species, especially given how fast the climate keeps changing. Lauren Sommer, NPR News.
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