Until now, white sharks have been thought to be mostly solitary creatures, swimming solo for much of their lives. But what if, as new research seems to suggest, they’re more social than we thought?
Motivated by mysteries that remain after 20 years of research, a dozen scientists led by Stanford biology professor Barbara Block headed out to sea this spring on a month-long trip to study one of the oddest hangouts on the planet—a section of the deep ocean researchers have dubbed the White Shark Café.
Halfway between Hawaii and Baja, hundreds of the large predators congregate. Block and her team are trying to figure out why. Is it for sex and companionship, a tasty snack or something else?
The White Shark Café seems to be a “meet and greet spot,” Block says. One Monterey Bay Aquarium colleague likened the gathering to Burning Man, an annual gathering in the Nevada desert that attracts seekers of all stripes.
“There may be a complex animal community at the café,” says Randall Kochevar, a collaborator on the project and director of the nonprofit Education Development Center’s Oceans of Data Institute. The sharks’ behavior once there is baffling. The massive fish spend their time diving to depths of 1,000 feet as often as once every 10 minutes. “[They] may be diving down to the deep scattering layer, which is made up of living organisms, and getting some snacks—having a little squid sandwich.”
You know, as you would at the White Shark Café.
“We think there may be other reasons they are coming out into the clear blue subtropical gyre,” Block wrote from the boat, describing the system of currents where the sharks converge. “What makes the sharks cool is they go to a specific area about the size of New Mexico. Prior efforts over 18 years defined the region—we now have taken the expedition, too.”
From mid-April to mid-May, Block’s research team from Hopkins Marine Station and the Monterey Bay Aquarium, as well as 30 crew members, lived on the Falkor, a 290-foot research vessel owned by the Schmidt Ocean Institute. Relying on information collected over two decades from the satellite tags that Block and others attached to white sharks, the team confirmed that from November to January, the sharks populate California’s coastal waters and feed on an abundance of elephant seals and sea lions. Then they head out to open ocean, and many visit the café, where they linger through spring. So far, it is impossible to know the precise number that frequent the area, since fewer than 100 white sharks have been tagged.
The trick to learning more about their behavior is to track the sharks to the café and then gather information on what is happening in that region of the ocean—physically, chemically and biologically. That’s a tall order: Block compares locating the tagged sharks in open ocean to “looking for a moose in Montana using a VW bus.”
When a tag “pops up” (the tags are programmed to release from the sharks and rise to the surface on a specific date), Kochevar says, it is as if “the moose just sent up a flare.” Once a tag surfaces, it begins to transmit a summary of its data through a satellite system back to the lab. This summary contains daily position estimates, along with a temperature and depth profile from its deepest dive of each day. This information allows scientists to ascertain the path that the animal followed, along with how deep it was diving and what conditions it experienced in the water column.
The combination of data collected from tags, advanced tracking devices, sampling nets and sophisticated submersibles fitted with underwater cameras should answer the mystery of why the sharks gather, and why they gather in that location. Block and her team also hope their findings will support conservationists in protecting the area, since many species that live there are vulnerable to overfishing and environmental degradation.
“The research illustrates how little we know about our planet,” observes Block. “One of the most iconic sharks on earth is half of the year in the open ocean—these ecosystems we actually know little about.”
Melinda Sacks is a senior writer at Stanford Magazine.
