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In case you were wondering: There are more shark attacks in U.S. waters than in any other region of the world.

By Becky Oskin
LiveScience

A 15-foot-long (4.5 meters) great white shark unexpectedly veered toward California last week, an unusual winter trip never before tracked by researchers. Scientists monitor the sharks using satellite tags.

The female great white shark, called Arden Grace, swam around Southern California's Channel Islands, visiting San Miguel Island and San Clemente Islands, beginning Feb. 14. Arden Grace, who has a satellite tracking tag on her dorsal fin, was likely hunting seals that live on the islands, said Michael Domeier, president of the Marine Conservation Science Institute, the Hawaii-based nonprofit research organization that tagged Arden Grace.

"She may be cruising the California coast and eating California seals," he said.

The trip is surprising for several reasons, Domeier said. First, Arden Grace is part of a population group based around Guadalupe Island in the Pacific Ocean, west of Baja California, Mexico. She is the first adult Guadalupe Island shark known to enter coastal California waters, Domeier said. In 2008, a great white shark from Northern California's Farallon Islands group was tracked to Guadalupe Islands, but the two populations have never interbred, Domeier said. [Image Gallery: Great White Sharks]

Second, during this time of year, great white sharks from Mexico and California are usually found hundreds of miles offshore in the open ocean, in a region called the "White Shark Café," their shared offshore foraging area. "The timing is not at all what we would have expected from the more than 100 sharks we've tagged," Domeier said.

Finally, Arden Grace's coastal exploration may be a sign she's not pregnant, though her size indicates she's a mature adult, Domeier said. Water is warmer in the shared feeding grounds, and some scientists think pregnant sharks prefer the balmy temperatures. "When mature females are pupping, they stay offshore in the middle of the ocean for 16 months," he said.

Tracking from Arden Grace's tag dropped off Tuesday, because the shark is underwater, Domeier said. "She's got her head down and we're not sure where she's going to pop up," he said. "I suspect she's going to turn around pretty quickly and head offshore, but she may really surprise us and go up into Central California. "

You can track the next stops on Arden Grace's journey via the MCSI's Expedition White Shark app or on its Facebook page.

"There always seems to be a new chapter to great white sharks, and the more research we do, the more we learn about them. They continue to surprise us," Domeier said.

Reach Becky Oskin at boskin@techmedianetwork.com. Follow her on Twitter @beckyoskin. 

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