Great White Sharks Are Closer Than You Think
A new study shows that these fierce ocean hunters swim near beaches—but they don't treat people as prey
The white lines show the specific paths of two of the tagged sharks in the study. (Map: Jim McMahon)
Picture a great white shark. Do you think of the giant predator hunting deep in the ocean, hundreds of miles from the beach where you might swim with your family? Many scientists assumed that that’s how great white sharks spent most of their time, only rarely coming near the coastal areas that might bring them close to humans.
A new study, however, shows some surprising results: Pacific great white sharks swim much closer to busy beaches in California than people had believed. Several have even gone inside the San Francisco Bay, east of the Golden Gate Bridge.
But the study does not suggest that humans are in any more danger from sharks than scientists thought we were before these findings. Why? Because the sharks apparently just aren’t very interested in people.
For the study, 10 scientists tagged 179 great white sharks from 2000 to 2008, to track the animals’ movements. The tracked movements showed that the sharks spend several months a year in waters off central and northern California, sometimes passing close to beaches where swimmers and surfers gather. The sharks are drawn to these areas by prey, such as elephant seals and sea lions.
Tagging and Tracking the Sharks
Researchers lured sharks to their boat with a decoy, or fake prey, in the shape of a seal, a favorite shark meal. Then, with darts, they attached two kinds of tags to track movement: satellite tags that give a rough location, and acoustic, or sound-based, tags that provide a precise location when the animal swims near a receiver that picks up sound waves.
The scientists set up four of the receivers in areas off the California coastline. All four areas have large colonies of typical prey for the sharks—seals and sea lions. The researchers did not expect their tagged subjects to enter San Francisco Bay. They learned this by accident when the sharks set off receivers in the Bay that had been set up there by a different research team tracking salmon.
The Man-eater Myth
The researchers don’t see any cause for alarm in the Bay area or on Pacific beaches. If a “major concentration” of great white sharks has spent this much time close to the coast without humans noticing before, then it “shows us the sharks are really minding their own business,” said Salvador J. Jorgenson of Stanford University, the study’s lead author.
The study, in fact, reinforces what history has shown: Despite its reputation as a ferocious man-eater, the largest predatory fish on the planet mostly stays away from humans. Since 1952, there have been only 10 deadly shark attacks in California waters. More people die from dog bites or hitting a deer with their car than from shark attacks.
New Findings About Migration
The tags also helped the researchers learn about the migration patterns of the great whites. Many scientists had believed that sharks roam the ocean randomly. Instead, they discovered that the sharks migrate along very precise routes. Starting from the California coastline in late winter, they swim thousands of miles across the Pacific, often as far as Hawaii. One spot in the migration area has been nicknamed the “White Shark Café,” because so many sharks gather there. In late summer, they return to the California coast, sometimes to a spot within a half-mile of where they started.
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