Satellites Clear Up White Shark Mysteries

Hillary Mayell
for National Geographic News
January 3, 2002

The first thing a wildlife biologist will tell you about white sharks is that their near-legendary status as man-eaters is undeserved. The second thing they'll tell you is that very little is known about white sharks.

How long they live, where they go to breed, how many there are, how often they reproduce, how deep they dive—the questions are endless.

Now, thanks to satellite technology, scientists are beginning to obtain answers—some of them surprising.

The findings show that white sharks travel farther and dive deeper than previously thought. They also spend nearly half of their time in deep ocean waters, which challenges earlier assumptions that white sharks spend most, if not all, of their time close to the coastline along the continental shelf.

The results came from a study by a team of California-based researchers who tagged six white sharks and tracked their movements to the depths of the ocean. The study, published in the January 3 issue of the journal Nature, offers the most extensive record ever compiled on the ecological niche of white sharks.

Information such as this is crucial to develop effective conservation measures. The World Conservation Union (IUCN) considers white sharks (Carcharodon carcharias) threatened globally.

Filling in the Blanks

Until now, scientists believed that white sharks lived in temperate, near-shore waters, where they occasionally attack swimmers.

"They might make a mistake and bite a person thinking it's a seal, but they don't usually come back to eat a person," said Peter Pyle, a marine biologist at the Point Reyes Bird Observatory in California and a co-author of the study in Nature. "The few fatalities [that occur] are usually the result of a particularly hard first hit," he noted.

To determine the sharks' range, the researchers applied data-recording tags to six sharks off the coast of San Francisco, then followed their movements.

"We knew the sharks left the area every year, and that the males returned each fall," said Pyle. "But we didn't have any idea where they went. We thought they might be going down to the waters off the coast of Baja, Mexico. To find they traveled west and so far was a surprise."

Earlier efforts to track white sharks had failed, in part because the available technology was less advanced.

Continued on Next Page >>


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