National Geographic : 2016 Jul
92 national geographic • JULY 2016 Primary range Migratory range Hub of activity 0mi SCALE AT THE EQUATOR 3,000 0km 3,000 INDIAN OCEAN PACIFIC OCEAN PACIFIC OCEAN ARCTIC OCEAN ATLANTIC OCEAN SOUTH AMERICA EUROPE ANTARCTICA AFRICA ASIA NORTH AMERICA UNITED STATES SOUTH AFRICA JAPAN INDONESIA INDONESIA U.S . HAWAII (U.S.) TAIWAN CALIFORNIA MASS. MEXICO AUSTRALIA CHINA NEWZEALAND Cape Cod Guadalupe Island Neptune Islands Baja California 6,900 mi Great white shark “café” Some great white sharks migrate seasonally over very long distances. EQUATOR ANTARCTIC CIRCLE TROPIC OF CAPRICORN TROPIC OF CANCER ARCTIC CIRCLE White sharks maintain a constant body-core temperature of regardless of surrounding water temperatures. Red muscle White muscle Cool water A vein running from the red muscle delivers warm blood to the brain. Heat-exchange system Warmed organs Heat is transferred between vessels. Liver Stomach Stomach Intestine Red muscle 79°F Metabolic heat Great white Most sharks Internal organs Gills Gills Tissue Tissue Circulating blood Great white Most sharks A 24-foot fishing boat sits just off the south- ern tip of Cape Cod, Massachusetts, on a perfect summer afternoon. The passengers—three sci- entists, two paying customers, two journalists, and the boat’s captain—lounge on the seats, look- ing off toward Nantucket. The voice of a spotter pilot flying 1,000 feet above breaks out over the radio in a sharp New England accent. “ We’ve got a wicked nice shark over here to the south!” Fisheries biologist Greg Skomal perks up. He’s standing five feet off the bow on the pulpit, a fenced-in walkway resembling a pirate’s plank. If this were a Hollywood movie, he’d have a harpoon and a peg leg. Instead he carries a GoPro camera attached to a 10-foot pole. He grins like a little kid as the captain guns the engine. Before 2004 hardly anyone in modern times saw great white sharks in the waters off the East Coast. Occasionally one would appear near a beach or in a fishing net, but they were anomalies. Elsewhere, great whites congregate seasonally around five “hubs” or territories, including Cal- ifornia’s coast down to Mexico’s Baja California, South Africa’s southern shores, and Australia’s southern coast, where they gather to feed on seals. But there’s been no hub on the East Coast, nor have there been many seals. Sharks here were wanderers without a home. Then, in 2004, a single female found her way into shallow inlets and shoals near Woods Hole, Massachusetts. For Skomal, who’d been tagging other sharks for 20 years, this was the chance of a lifetime—a great white in his own backyard. “I thought it was a fluke. This will never happen again,” he says with his broad, boyish grin under ruffled salt-and-pepper hair. Over the next two weeks The Realm of the Great White The great white is one of six shark species that are endothermic, which means they can raise internal body temperatures over that of surrounding waters. This allows great whites to inhabit extreme depths as well as cold waters of higher latitudes, while still being able to function efficiently to capture swift and agile prey.