Tiny group of whales in Gulf of Mexico is a new species

The tiny group of endangered whales that make the Gulf of Mexico their home turns out to be a previously unknown species.

The best count is that there are about 33 of the long, slender filter feeders — and definitely fewer than 100 of them. They’re listed as endangered in the U.S. and as critically endangered by the International Union for Conservation of Nature.

They were classified as one of three of Bryde’s (pronounced BROO-duhs) whale subspecies, but many scientists suspected they were something different.

Pamela Rosel of the National Oceanic and Atmospheric Administration recently published confirmation that it’s a previously unknown species.

“A very exciting paper!” Lori Schwacke, chief scientist for conservation medicine at the National Marine Mammal Foundation and not one of Rosel’s co-authors, wrote in an email to The Associated Press.

“It’s such a small population in the Gulf of Mexico that marine scientists and managers were already focused on conservation efforts for them, particularly after the Deepwater Horizon oil spill,” said Schwacke. “But now confirming that these whales are indeed a previously unknown species really raises those stakes.”

Rosel’s article in Marine Mammal Science used DNA, bones and reports of sightings and strandings to show the whales are unique. Rosel, who works at NOAA’s Southeast Fisheries Science Center in Lafayette, named the new species Rice’s whale after the scientist who first recognized that the whales lived in the Gulf.

A dead whale that washed up in Florida in 2019 was the breakthrough, she told The Times-Picayune / The New Orleans Advocate.

“They’re so rare that it was our first opportunity to see a complete and intact specimen,” said Rosel. That brought mixed emotions.

“I was happy but also sad because we’d lost a whale from such a small population,” she said. “But it allowed us to confirm it’s a different species. That’s such a great scientific step forward and could help with its conservation.”

The whales also behave differently. Unlike their ocean-going cousins, the Gulf whales have never been seen feeding at the surface, Rosel noted in her paper. A suction-cup tag attached to one in 2010 found that the whale stayed within 15 meters of the surface at night and repeatedly dived deep during the day, sometimes with “lunges near the seafloor associated with foraging.”

“This type of bottom feeding is unusual” among similar whales, she wrote.

Nobody knows what they were eating, she wrote, but lanternfish and hatchetfish are abundant at the depths the whale reached.

“Further work to identify primary prey species and foraging behaviors is needed and will be important for identifying potential threats and important habitat for these whales,” Rosel wrote.