The Steller’s sea cow was almost extinct by the time German naturalist Georg Wilhelm Steller first laid eyes on the plump marine mammal. The species that would bear his name once ranged throughout the North Pacific, but by the time of Steller’s visit in 1741, the last population was sequestered around Russia’s Commander Islands. The species was hunted into extinction before the close of the 18th century.
Then, a discovery complicated this classic story of extinction. In 2014, George Mason University biologist Lorelei Crerar and her coauthors announced that a hidden population of Steller’s sea cow bobbed through the waters around St. Lawrence Island, west of the Alaskan coast, up until about 1,000 years ago.
Why this second pocket went extinct wasn’t clear—in their report in Biology Letters, the researchers proposed that a brief uptick in temperatures called the Medieval Warm Period could have made the kelp the marine mammals ate harder to find, or that Inuit hunted them into extinction. Either way, the discovery of this “hidden” population added a new wrinkle to the animal's tragic tale.
Now the study is making waves for a very different reason: It highlights the squishy state of regulations surrounding “mermaid ivory,” the colorful name for the bones of marine mammals carved into sculptures, and what that means for scientific research.
For their work, Crerar and her coauthors used bone specimens bought at knife shows and on Ebay. The bone dealers assured them that the samples came from St. Lawrence Island. The team's initial intention was to detect whether protected marine species were being illegally traded under the banner of mermaid ivory, says study co-author Chris Parsons. Their genetic analysis identified some of the samples as Steller's sea cow, and those bones were dated at about 1,000 years old, which Crerar and Parsons deem a serendipitous result.
But not everyone is sold on the idea that the sea cows inhabited the waters around St. Lawrence Island way back when. In a response article published this month in Biology Letters, marine mammal experts Nicholas Pyenson, James Parham and Jorge Velez-Juarbe question where these critical sea cow bones came from and, more broadly, how commercially purchased specimens are used in studying the past.
“While I certainly hope that the material did come from St. Lawrence Island, we have no basis, given the current facts, to affirm this geographic placement with confidence,” says Pyenson, of the Smithsonian's National Museum of Natural History. Location is just as important as anatomy or tatters of genes in examining where species used to live. Even though it was not Crerar and colleagues' intention to conduct a paleontological study, Pyenson and his coauthors are dismayed that there is no concrete evidence for where the bone samples came from.
A bone sold as mermaid ivory is stripped of its context and can only give you scant anatomical details, Parham says. “Because the fossil record is so incomplete already, any time we lose attendant data, the science suffers.” Promises from bone dealers are not sufficient, he adds. “In science, you should not really pick and choose which merchant to believe.”
Complicating matters, this species falls through a regulatory loophole.
“The specimens in question fall outside of the Marine Mammal Protection Act, because Steller’s sea cow is extinct. And because these specimens are not technically fossils either, they fall outside of the Paleontological Resources Protection Act,” says Pyenson. That means dealers can legally buy and sell the bones without having to worry much about documenting their origins. And that makes the original study problematic, Pyenson says.
“I think their broad conclusions would be interesting and relevant to a more complex extinction scenario if we did have such traceability," he says. "But what confidence do we have that the isotopic and DNA results can be tracked to actual physical vouchers, given these issues?”
Pyenson and his coauthors are also concerned that the 2014 study grated against the standards of paleontology and other biological disciplines. The bones used in the 2014 study were held in a private collection, which was put in a George Mason University collection last December. That means the original specimens were privately held at the time they were formally described.
When important specimens are in private hands, the owner may deny access to scientists for any reason they like, the trio point out. "And then there’s always the question of what will happen to those specimens beyond the lifetime of the owner,” says Velez-Juarbe of the Natural History Museum of Los Angeles.
Reiterating that their initial findings were a happenstance that came out of a different project, the authors of the 2014 study dispute these arguments. In a published reply to Pyenson and his colleagues, Crerar says that the samples were not hard to access.
“All 200 of the bones are at George Mason University,” she says, with the exception of five that are currently at the Smithsonian, and she says that other researchers have already examined the collection. And while Crerar would also like to know more about where the bones came from, she has not yet visited St. Lawrence Island and talk to the people who dig the bones from middens.
Parsons adds that he is “dumbfounded by the furor over the samples,” especially because the sea cow samples “are tiny fragments that aren’t really recognizable as bones or carvings.” He likens them to genetic tissue samples, which are not always stored in museum collections.
Still, archiving genetic samples has rapidly become a scientific standard for biologists, and museums and zoos around the world are building huge collections of frozen tissues, says Parham of California State University.
While the tricky nature of mermaid ivory may not be resolved any time soon, there is some hope for resolving the mystery of the St. Lawrence Island sea cows. Middens likely to harbor more sea cow bones have previously been excavated on the islands, and their fully documented contents are now being cared for at museums, say Pyenson, Parham and Velez-Juarbe.
“Could there be Steller’s sea cow already in museum collections at Fairbanks?” Pyenson wonders. “I’m going to go and find out.”