The sharks, who have a regular migration pattern, have been spotted in the area known as the Red Triangle -- from Monterey Bay to the south of San Francisco, Bodega Head to the north and the Farallon Islands 30 miles to the west -- the San Francisco Chronicle reported. About 100 have been radio-tagged, allowing scientists to track their movements.
The Wave Glider, which is carried through the water by wave energy and includes a GPS in its tool kit, is back in the San Francisco area, the Chronicle said.
"What we are trying to build right now is a wired ocean with a network of interactive devices that will tell us where the animals are," said Barbara Block, a professor at Stanford University's Hopkins Marine Station.
About 220 great whites spent the fall in the Red Triangle last year.
"We're just talking about adults, which have very regular migratory patterns and return to the same area every year," said Salvador Jorgensen of the Monterey Bay Aquarium. "There is an unknown number of juveniles and babies ... but we don't know how many there are, because they are not concentrated in one area like the adults are."
The sharks will swim out to sea again in December, heading for a deep-water area off Hawaii nicknamed the Great White Cafe.