The Brazilian Navy spotted something unusual in the azure waters of the South Atlantic.
In 2015, at a remote outpost and biological research station on the island of Trindade, 1,100 kilometres off central Brazil, sailors spotted a small gray seal swimming in the waves.
Two days later, they found its body on the island’s Catelha beach. Scientists who went to take a closer look made an astonishing discovery—the corpse was a young Weddell seal.
The polar animal had travelled more than 5,000 kilometres north of its Antarctic habitat—and more than 1,500 kilometres beyond the farthest north the species was previously recorded in Uruguay.
“This is the farthest north this seal has ever been spotted. It’s a long way, even from the northernmost part of the breeding area,” says study co-author Guilherme Frainer, of the Federal University of Rio Grande do Sul in Brazil.
Frainer, a marine biologist who was on Trindade researching bottlenose dolphins, wasn’t surprised to hear that an animal had washed ashore; the island is notorious for strandings and beachings.
“But I was shocked when I realised it was [likely] a Weddell seal,” he says.
LOST AT SEA
Frainer is not an expert in pinnipeds, the group of marine mammals that includes seals and sea lions. And since the seal was a juvenile, it lacked some of an adult's distinguishing features.
With no one around to make a conclusive ID, Frainer and the navy buried the seal on Catelha beach in July 2015, shortly after the animal was discovered.
In January 2017, however, Frainer returned to Trindade with fellow UFRGS marine biologist Vanessa Heissler. Exhuming the body and examining the jaw, Heissler made a conclusive identification. Their results were published last month in Polar Biology.
It's unknown why the seal died, but Luis Huckstadt, an expert on seals at the University of California, Santa Cruz, said it's not surprising the animal didn't make it.
"Usually when they're this far from home, the seals are disoriented, stressed, and in pretty bad shape," Huckstadt says.
So how did the lost seal end up so far from home?
Weddell seals typically spend their lives in the frigid waters around Antarctica, although a few groups do breed as far north as the South Shetland Islands or South Georgia Island in the southern Atlantic. (See gorgeous photos of mysterious life under Antarctica.)
Lead Image: A Weddell seal rests on a volcanic beach in Antarctica in an undated file photograph. PHOTOGRAPH BY JASON EDWARDS, NATIONAL GEOGRAPHIC CREATIVE