How the Rice’s Whale Became a New Species

When a rare adult whale beached and died in Florida’s Everglades National Park in early 2019 experts immediately recognized its significance. The whale, they thought, belonged to a peculiar population of Bryde’s whales that reside year-round in the Gulf of Mexico. Tantalizingly little is known about these bus-sized whales and they appear to be on the knife-edge of extinction: only 26 to 44 whales likely remain alive. Although a dreadful loss to such a small and vulnerable population, the stranded whale gave scientists a once-in-a-lifetime chance to see whether this population of whales was actually a new species.

“I had been keeping an eye out for a specimen like this,” says John Ososky, collection manager of marine mammals at the Smithsonian National Museum of Natural History. Not only is it rare to come across stranded whales from this scant population, this specimen was both intact and an adult. Ososky jumped on the opportunity to secure it for study at the Smithsonian.

But transporting the washed-up whale across the country took ingenuity and a massive effort. He “pleaded, begged and whined” with those on the scene of the stranding to make sure the whale was preserved until he could make the necessary arrangements to travel to Florida to collect and process the near-30-ton carcass.

Faced with the problem of storing a rapidly decomposing whale for several months, authorities buried the carcass in a secluded sandbar. Ososky then undertook the arduous, gruesome and deeply meaningful journey to exhume the skeletal remains and take them for cleaning at the Bonehenge Whale Center in North Carolina, from where they were later transported to Smithsonian’s whale warehouse in Suitland, Maryland.

His efforts paid off. A new study led by NOAA scientists presents a morphological analysis of the recovered specimen’s skull and skeleton. The article, published in January 2021 in Marine Mammal Biology, confirms that the whales in the Gulf of Mexico are not Bryde’s whales after all, they belong to a distinct new species. The specimen from Florida now serves as the species holotype, the standard representation of the new species. Findings from 2014 already indicated that the whales in the Gulf of Mexico are genetically distinct from closely related whales based on mitochondrial DNA. The new measurements taken of the washed-up whale’s skull and skeleton confirm that these animals do indeed differ from other whales around the world.

“The [genetic and morphological] datasets provide two independent lines of evidence that indicate that they differ enough to warrant species status,” says Patricia Rosel, a geneticist from NOAA’s Southeast Fisheries Science Center and lead author of the study.

The new species is named Rice’s whale (Balaenoptera ricei) in tribute to Dale Rice, the biologist who first recognized the population of whales in the Gulf of Mexico. With only dozens of individuals remaining, the marine mammal is now one of the most endangered species of whales in the world.

“This animal is in trouble,” says Ososky. “There are plenty new species that get named out of the ocean routinely, but not like this. Not a big charismatic animal on the brink of extinction.”

Despite differences in their DNA and skeletal morphology, Rice’s and Bryde’s whales are superficially very similar. Their bodies are sleek and streamlined and can grow up to 42 feet long and weigh as much as 30 tons. Both sport three ridges on the top of their heads that help to distinguish them from other baleen whales. Although both species are filter-feeding baleen whales, they appear to have starkly different foraging strategies. While Bryde’s whales—which range across the Atlantic, Pacific and Indian oceans—have been observed to feed on small fish close to the surface, Rice’s whales dive deep and feed near to the seabed.

“Exactly what fish they’re eating down there, we still don’t know,” Rosel says.

Investigation of the stomach contents of the whale that beached in Florida did not clarify this mystery. The whale was emaciated, and its stomach was empty. It had likely stopped feeding long ago due to a piece of sharp plastic debris found lodged in its digestive system.

Ingesting ocean debris is one of many hazards that threaten the survival of Rice’s whales. Distribution studies suggest that these whales are remarkably faithful to the deep waters of DeSoto Canyon in the northeastern Gulf where human pressures are intense. Other threats to the whales there include oil and gas exploration, oil spills and cleanups, vessel strikes, ocean noise and entanglement in fishing gear.

In 2010, BP’s Deepwater Horizon oil spill affected 48 percent of the Rice’s whale known habitat and an estimated 17 percent of their population was killed by the incident, according to NOAA’s Natural Resource Damage Assessment report. Moreover, chemicals used to disperse oil during clean-up operations likely bioaccumulated in the whales’ bodies, leading to reproductive failure and widespread health problems, according to the marine charity Whale and Dolphin Conservation.

Conservationists are particularly concerned about the effects of widespread seismic testing for oil and gas exploration in the Gulf of Mexico. Whales are also disrupted by the constant stream of large service and container vessels transiting their primary habitat. “Whales live in a world of sound, and any excessive noise pollution can affect breeding, feeding and communication between individuals,” says Danny Groves, Whale and Dolphin Conservation communications manager. “Noise pollution can drive whales away from the areas that are important for them and also cause strandings.”

Conservation scientists hope that the whale’s heightened species status will solidify further efforts to study and to mitigate threats to the species.

“By being designated as a new species, a whole lot of levers of conservation come into play,” says Michael McGowen, research scientist and curator of marine mammals at the Smithsonian NMNH, who was not involved in the study. “It makes everyone’s heads turn a bit more.”

Bryde’s whales—including the Gulf of Mexico population—were granted protection under the Endangered Species Act (ESA) in 2019. Rice’s whales will now retain ESA protected status under the new species name. They receive further protection under the Marine Mammal Protection Act, which prohibits harming or harassing whales in U.S. waters.

Rosel asserts an urgent need to gain a greater understanding of Rice’s whales’ basic biology and movements, such as where they roam, what they eat and how they communicate, so that conservation and protection measures can be planned and implemented. However, studying these enigmatic whales is not easy. In addition to their scarcity, they are wary of vessels, “so even if you know where they might be, you’re never guaranteed you’re going to see one,” she says.

Future research on the Rice’s whale specimen in the Smithsonian’s collection will investigate that particular whale’s life history by analyzing its baleen to generate information about its toxicity, hormone profile and stress levels. By gathering such information, scientists will be able to gauge what human activities affect the species.

“We have this whale in American waters. It’s new and it’s on the brink of extinction,” says Ososky. “What are we willing to do to save this whale? That is a conversation that we should have.”

Action to remove or reduce threats to the whale’s primary habitat is crucial. Since the bulk of the species’ population occurs in U.S. waters, conservation groups are now calling for federal designation of critical Rice’s whale habitat in the Gulf of Mexico. They are also pressing NOAA for a finalized recovery plan that outlines the initiatives necessary for species recovery. Measures that could make a difference include limiting or halting seismic surveys within the listening range of the whales’ primary habitat, establishing vessel speed reduction zones and exempting or modifying fishing activity.

According to Regina Asmutis-Silva, executive director of Whale and Dolphin Conservation North America, the future of Rice’s whale in the Gulf of Mexico “depends on how well we can raise awareness about a species that most of us will never see but which, like all whales, plays an integral role in our ecosystem, the health of our planet and our own future.”