It’s the world’s newest whale species—and it’s already endangered

Rice’s whales are among the world’s rarest marine mammals, with only about 50 surviving off Florida. How did scientists miss them—and how can we save them now?

By Melanie Haiken
Published 6 Feb 2023, 09:40 GMT
A Rice's whale (Balaenoptera ricei), previously called the Gulf of Mexico Bryde's whale, swims just below the surface in the Gulf of Mexico.
Photograph by NOAA Fisheries

It’s not often that scientists discover a new species of mammal, let alone one that reaches 40 feet in length, weighs up to 30 tons, and frequents the waters off a heavily populated area.

But that’s what happened in 2021 when scientists announced a new species: Rice’s whale, formerly thought to be a subspecies of Bryde’s whale.

The exciting news was accompanied by a much sadder announcement, however: the filter-feeding whales, often called the Gulf of Mexico whale because of their home base just south of the Florida panhandle, are critically endangered. Only 51 whales remain, according to researchers’ best estimates, making them one of the rarest marine mammals in the world. 

With their primary habitat smack in the middle of a busy shipping corridor, Rice’s whales live under constant threat of assault from vessel strikes, military training activities, oil and gas exploration, and environmental contamination. The Gulf oil spill in 2010 polluted almost half of the whales’ habitat, killed an estimated 17 percent of the remaining population, sickened another 18 percent, and left almost a quarter of females with reproductive problems.

With the clock ticking, scientists working with the U.S. National Oceanographic and Atmospheric Administration have launched a series of research projects to study the species more closely. (Learn why a whale’s world is full of sound.)

For instance, a recent study, published in January, used the rare whales’ distinctive vocalisations to track their movements, finding that the whales travel outside their main range, as far west as the coast of Texas.

“It was exciting to discover that they still regularly occur in the northwestern Gulf of Mexico,” says study leader Melissa Soldevilla, a research fisheries biologist for NOAA. “Historic records suggest that they used to be more broadly distributed throughout the Gulf, but no whales had been seen beyond the core habitat since the 1990s.”

Mapping the whales’ distribution is a necessity for defining their critical habitat under the Endangered Species Act, a process that is currently underway and would become the basis for legal protections.

“Once we understand where and when the whales occur, we can determine where they overlap with human activities that may pose a threat to them,” Soldevilla says. “This helps us identify and develop management and conservation actions to reduce the threat and improve their chances of recovery.”

A skull leads to a new species

Rice’s whales have long intrigued scientists, who began studying their anatomy almost two decades ago. Genetic evidence had suggested the whales were a distinct species, but it took a skull washing up in the Florida Everglades in 2019 to provide a definitive answer. (See 14 jaw-dropping photos of whales.)

“With this specimen, it was finally possible to put all the lines of evidence together and write the scientific paper describing the new species,” says Patricia Rosel, a NOAA research geneticist who led the study identifying Rice’s whales, named for the late marine biologist Dale Rice, who first noted the whales’ special characteristics.

Soon after their discovery, NOAA developed a recovery plan for the species, which calls for reducing vessel strikes and protecting the whales’ habitat from threats associated with energy development, including noise from seismic surveys, as well as oil spills.

Seismic testing, or airgun blasting, a tool used in oil and gas exploration that gained legal approval in 2018, poses the newest threat by potentially interfering with the whales’ communication, sonar navigation, and feeding.

“Hearing for them is like sight for us, they use it for everything,” says Kaitlin Frasier, a marine research assistant at the Scripps Institute of Oceanography who studies Rice’s whales. “Sound travels so well underwater, and these guys have evolved to take advantage of that. By injecting our noise, we’re making it harder for them to do what they need to do to survive.” (Read about a groundbreaking effort to decode whale language.)

Frasier co-authored a 2022 study, with Soldevilla, that placed devices on the ocean floor, as well as acoustic tags attached to Rice’s whales, to show the cetaceans make several unique calls that could be interrupted by human-made noise. The research also revealed Rice’s whales sleep floating close to the surface, making them vulnerable to ship strikes and other threats.

“Acoustic tracking is one of the best things we’ve come up with to figure out where the important habitats are and do what we can to make life less stressful in those areas,” Frasier says.

Meanwhile, some scientists and conservationists want the government to pick up the pace.

In October 2022, a group of a hundred international marine scientists released an open letter calling on the U.S. Biden administration to do more to protect Rice’s whales. And several lawsuits are working their way through the courts, including one filed by the Natural Resources Defence Council calling for a halt to airgun blasting.

“We really want to do everything possible to keep these guys alive and get their population going again,” says Frasier. 

“There’s a lot more research to be done, but first you have to get everybody’s attention and make sure people realize this is a real issue—before it’s too late.”


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