National Geographic : 2016 Aug
120 national geographic • august 2016 0mi SCALE AT THE EQUATOR 3,000 0km 3,000 0-410 feet Area of highest vulnerability to fishing gear 1,000 feet Surface 4,000 3,000 2,000 Minutes Slower ascent (foraging) Sept. 15 Sept. 1 Aug. 15 Pectoral 10 54 Fast descent Lower caudal lobe Fin needles Cartilage First dorsal Estimated population decline between 1995 and 2010 93% Tracked vertical movements of a tagged oceanic whitetip shark INDIAN OCEAN PACIFIC OCEAN PACIFIC OCEAN Gulf of Mexico Red Sea Mediterranean Sea ARCTIC OCEAN ATLANTIC OCEAN SOUTH AMERICA EUROPE AUSTRALIA ANTARCTICA AFRICA ASIA NORTH AMERICA Cat I. UNITED STATES BAHAMAS CUBA SOUTH AFRICA U.S. HAWAII (U.S.) CAYMAN IS. (U.K.) JAPAN PHILIPPINES U.S.S. Indianapolis July 30, 1945 Oceanic whitetips prefer the open ocean and are rare in shallow coastal waters. EQUATOR ANTARCTIC CIRCLE TROPIC OF CAPRICORN TROPIC OF CANCER ARCTIC CIRCLE Oceanic whitetip range Primary Uncertain but they didn’t bother us.” Lyle Umenhoffer, 92, told me, “You had to be alert when those sharks were around, and if they got too close, you’d kick them away. But I don’t think I was really afraid of them. We had other problems.” (Umenhoffer has since passed away.) Now it should be said that by the time they were rescued, the survivors were spread across an area of more than a hundred square miles, and their experiences varied. And it should also be said that the dead might tell different tales. But no man I spoke to at a survivors’ reunion last summer—14 of the remaining 31 survivors were present, and I interviewed most of them— would put sharks at the top of his list of concerns during the ordeal. Technically, Quint was right that the sharks took “the rest”—that is, the men who never made it out of the water—but most of those men actually died from other causes: injuries, hypothermia, drowning, dehydration, and saltwater poisoning. “I seen men die from sharks—a few of them,” said survivor Dick Thel- en, 89. But he saw two or three times as many men die from drinking seawater. As one person at the reunion put it to me, “Quint doesn’t say anything about being thirsty.” It’s important to get the story straight be- cause the portrayal of oceanic whitetips as voracious killers and, as such, an expendable species may have damaging consequences. On land, the effect of removing dominant preda- tors is well understood: It creates ecological havoc. (In parts of Africa, for example, dimin- ished lion and leopard populations have led to a rise in both baboons and their intestinal para- sites, which are increasingly infecting humans.) What effect has oceanic whitetips’ virtual dis- appearance had on ocean ecosystems where these animals once loomed so large? We have no idea. Zero. So little research has been done Whitetip Tipping Point Hunted for their fins and often hooked as bycatch by longline commercial vessels, oceanic whitetip sharks are in steep decline. They have few offspring (two to three pups in a litter) and don’t reach sexual maturity until around seven years—traits that impede population recovery. They tend to inhabit remote parts of open ocean, making them difficult to study.