On the Trail of a Great White

April 7, 2008 -- Researchers, and anyone else with Internet access, may now track near real-time movements of a juvenile great white shark that was released into the wild by the Monterey Bay Aquarium, which featured the toothsome predator in an exhibit that lasted 5 1/2 months.

As of this writing, the shark is headed toward waters off the Mexican mainland and is now just north of Mazatlan.

"We're confident the shark is doing well, but the big question is whether or not it will fall victim to fishing pressures in Mexico," Monterey Bay Aquarium spokesman Ken Peterson told Discovery News.

"Sharks often wind up as bycatch in fishing operations, so we hope he'll be able to avoid all of the gear," Peterson added.

The shark thus far has evaded other popular fishing grounds. Since it was released six weeks ago, the great white has swum southward, hugging the California coastline and traveling past the southern tip of Baja California.

Where it's ultimately headed is anyone's guess.

"The lives of juvenile white sharks are almost a complete mystery to us," Peterson said. "The released shark is now in relatively warm waters about 656 feet deep, but we don't know if it will travel into the Sea of Cortez, where juvenile great whites have been spotted, or if it will travel more southward, where we have less evidence for shark presence."

He explained that younger great white sharks tend to stay in warm water where they consume fish. As they get older, they often switch to colder water and to hunting and eating mammals, which provide more nutrition and calories.

While the Monterey Bay Aquarium has successfully released all three of the great whites it has had on exhibit since 2004, this latest shark is the first to carry two different tracking tags.

The tag that allows for the day-to-day monitoring is called a Smart Position-Only Tag, or SPOT. It transmits the shark's location via satellite whenever the shark's dorsal fin breaks the surface of the water and the tag makes contact with the satellite. So far, data has been coming in about every two days.

The second tag logs where the shark travels, including water temperature and depth. It is programmed to pop free July 2, when it will transmit its stored data via satellite to researchers at the aquarium and at Stanford University's Hopkins Marine Station in Pacific Grove, Calif.

The information has provided new insights into the far-ranging travels of white sharks in the eastern Pacific, according to Barbara Block, a marine biologist at the station and a principal investigator at TOPP (Tagging of Pacific Pelagics).