A group of researchers is tracking the gradual return of northern fur seals to the Bay Area of California. The seals were once prized for their thick, warm fur, and they were hunted nearly to extinction in the 1800s. A century later, they’re slowly repopulating the Farallon National Wildlife Refuge
Seals were nearly hunted out of existence on California’s Farallon Islands, and now their remarkable comeback is challenged by warm waters.
By Nadia Drake , National Geographic PUBLISHED Tue Dec 22 13:44:25 EST 2015
SAN FRANCISCO—Nearly 30 miles west of the Golden Gate Bridge, a growing population of feisty, fish-loving northern fur seals is waddling around the craggy Farallon Islands. After all but vanishing from these granite shores by the mid-1800s, the seals have been returning in ever-increasing numbers—just in time to take a hit from a strong, brewing El Niño. Scientists expect the challenging ocean conditions offshore will affect multiple species, and say the situation is a preview of what could come if warming trends continue. “Northern fur seals are dramatically affected by El Niños,” says Tony Orr, a wildlife biologist with NOAA’s Alaska Fisheries Science Center. Yet he’s optimistic that the population will rebound. “Their numbers do get smacked down, and it takes a while, but they gradually recover.”
Ups and Downs
Since 2013, the fur seal population in the Farallon National Wildlife Refuge has doubled from 666 to more than 1,200, Ryan Berger of Point Blue Conservation Science reported last Tuesday at a conference of the Society for Marine Mammalogy. “It’s a huge increase,” Berger says. Berger and his colleagues have been studying the fur seals on the chain’s West End Island since 1996, when the first pup was born there in more than a century. Biologists working on the island count the number of adults and pups annually, aided by aerial surveys conducted with the U.S. Fish and Wildlife Service.
In the early 1800s, the Farallons hosted more than 100,000 northern fur seals. But over a period of 40 years, hunters with their sights set on the seals’ dense, coveted coats robbed the islands of their flippered inhabitants, reducing the population to basically zero. In recent years, the seals have started to find their way back to these wind-whipped rocks from breeding grounds in southern California and Alaska, and it looks like some will stay put. The news isn’t all good, though. Only 665 pups were born this year, just nine more than the 2014 total of 656. That’s not entirely unexpected in El Niño years, when warm ocean waters make food scarce for mothers and just-weaned pups; in fact, surveys suggest young fur seals often don’t survive at all. Orr says he and his colleagues have never spotted any tagged pups born during the last extreme El Niño winter, in 1997–1998. “None of them have ever been seen. Ever. That’s crazy,” says Orr. “Their population just crashes during El Niños.”….