A New Species of the World’s Biggest Whale Has Been Discovered—and They’re Small

by Taylor Hill

Does the world’s largest animal have a pint-size variety?

Not exactly, but the population of blue whales living off Chile’s southern coast could be a slightly smaller version of their Antarctic neighbors, and that has scientists thinking they may have found a new subspecies of the cetacean.
But don’t be fooled: These so-called “pygmy blue whales” are only small if you’re comparing them with the 100-foot behemoths with which they share a name.

Still, the new findings—published in the journal Molecular Ecology on Thursday—should help researchers get closer to determining just how many types of blue whales exist in the world’s oceans, and that could make a big difference in understanding the best way to conserve the endangered species.

Researchers from the United States National Oceanic and Atmospheric Administration, the Wildlife Conservation Society, and the Universidad Austral de Chile worked together on the study, comparing the genetic identify of 52 whales found off southern Chile with blue whales from Antarctica, northern Chile, and the eastern tropical Pacific.
While they didn’t find differences between the Chile groups and the eastern tropical groups, there were significant differences in gene sequences in all three populations compared with the Antarctic blue whales.
“The presence of two types of blue whales in Chile hopefully helps inform protection measures, either via spatial protections or threat mitigations for each that can be carried out locally and nationally, but also in a regional and international context,” Howard Rosenbaum, a Wildlife Conservation Society director and senior author of the study, said in an email.
The smaller blue whales found off southern Chile are similar in size to another subspecies of blue whales found off Australia, called B. m. brevicauda—which measures around 80 feet at maturity. That’s plenty big, but it still doesn’t touch the Antarctic blue whale, B. m. intermedia, which can grow up to 100 feet in length.

Researchers noted that little is known about the Southern Hemisphere blue whale population, and most historical data points come from whaling records. It wasn’t until a blue whale feeding and nursing ground was discovered off Chile’s southern coast in 2004 that scientists began to question whether there was more than one population of blue whales in the southeastern Pacific.

By the early 1900s, whalers had slaughtered more than 300,000 Antarctic blue whales, depleting the population to less than 1 percent of its historic number.

Since the International Whaling Commission’s 1966 moratorium on killing blue whales, the marine mammal has slowly recovered, and there are now 5,000 to 10,000 of the massive animals in the Southern Hemisphere and 3,000 to 4,500 in the Northern Hemisphere.

“Our study gives us crucial insights into the population structure of blue whales in the waters of Chile and will serve as an important stepping stone for further research,” said Rosenbaum. “The long-term goal of such work would be a network of marine protected areas designed to save the world's largest animal.”