Salvador Jorgensen has spent more than 15 years studying great white sharks near California's coast. The senior research scientist from the Monterey Bay Aquarium and his team have attached tracking tags to 165 of the toothy predators, which routinely visit islands west of San Francisco and prey on elephant seals. But something odd happened one autumn: “In 2009, 17 of those tagged white sharks were simultaneously swimming around the Farallon Islands, when they abruptly departed. Not just one or two but all 17, in a matter of hours,” Jorgensen recalls. “Normally the sharks hang around for weeks or months at a time.”
