August 2016 National Geographic by Glenn Hughes
Oceanic whitetips, famous for attacking shipwrecked sailors, once ruled the seas. Now they’re nearly gone. They’ve been decimated as bycatch in longline commercial fishing as they travel mostly in the top of the water column, the same depths fishing boats target. Their deep dives are to find prey such as squid. The shark fin trade has had a similar devastating effect on the species. They have few offspring (2-3 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 the open ocean, making them difficult to study. Bahamas’ Cat Island, one of the last places the sharks reliably can be found. Before this tagging study, scientists knew little about the species.
With its winglike pectoral fins, the oceanic whitetip is built to glide through vast expanses of the ocean in search of prey. When it finds something that might be edible, it investigates relentlessly. The species’ reputation as ravenous killers is overblown, but divers still need nerve. The sharks aren’t shy. Their hello: a quick bump.
When the documentary Blue Water, White Death hit U.S. theaters in 1971, its footage of great white sharks crashing into diving cages became instantly iconic. But the footage that stands out 45 years later is a long scene showing oceanic whitetip sharks swarming a whale carcass a hundred miles off the coast of South Africa.
It is an amazing scene for two reasons: first, because the divers leave the safety of their cages to film the sharks, believed to be the first time anyone had ever tried the technique among feeding sharks. And second, because it’s a scene that might never be replicated—a marine version of the last photograph of endless bison herds roaming the North American plains. “You couldn’t count them, there were so many,” says Valerie Taylor, one of the divers. “It will never happen again—not in your lifetime. Maybe in someone else’s, but I doubt it.”
At one time oceanic whitetips were thought to have been among the most numerous pelagic (open ocean) sharks on the planet. An authoritative 1969 book, The Natural History of Sharks, even characterized them as “possibly the most abundant large animal, large being over 100 pounds, on the face of the Earth.” Once known for besieging shipwrecks and fishing boats, they’ve now all but disappeared because of commercial fishing and the shark fin trade—with surprisingly little scientific attention and even less public concern.
“We’ve absolutely annihilated the species on a global scale,” says Demian Chapman, one of the few scientists who have studied the shark. “And yet when I say ‘oceanic whitetips,’ a lot of people have no idea what I’m talking about.”
If you’ve seen Jaws, you know something of oceanic whitetips. They’re likely the predominant sharks that plagued the crew of the U.S.S.Indianapolis after it was sunk by a Japanese submarine near the end of World War II—an event made infamous to recent generations by Captain Quint’s monologue about his experience as a survivor of the sinking. It’s impossible to capture the chilling effect of Quint’s speech in words—let’s just say it’s full of screaming and bleeding—but the last line sums it up: “Eleven hundred men went into the water, 316 men came out, and the sharks took the rest.”
The problem with Quint’s story, though, is that while it gets the tangible facts more or less right, it badly misrepresents the crew’s experience. This much is true: Of the nearly 1,200 crew members on the Indianapolis, about 900 made it into the water alive, and most of those men died in a hellish ordeal over the next five days. Only 317 survived. There were sharks—lots of them—and gruesome shark attacks.
But when I asked Cleatus Lebow, 92, a soft-spoken Texan who was a crewman on the Indy, what the hardest part of his time in the water was, before I even finished my question he said, “Being thirsty. I’d have given anything for a cup of water.” What about the sharks? “You could see them swimming around sometimes, 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 Thelen, 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 because 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 predators is well understood: It creates ecological havoc. (In parts of Africa, for example, diminished lion and leopard populations have led to a rise in both baboons and their intestinal parasites, which are increasingly infecting humans.) What effect has oceanic whitetips’ virtual disappearance had on ocean ecosystems where these animals once loomed so large? We have no idea. Zero. So little research has been done on the species that even trying to understand the story of its own decline—never mind how that decline affects other species—feels like trying to assemble a jigsaw puzzle with most of the pieces missing. And if we mistake these sharks for villains, we’re not likely to feel any urgency about finding those missing pieces. If the Indianapolis sinking happened today, its crew would almost surely not be bothered by hordes of oceanic whitetips—and that should not be taken as good news.
Scuba pioneer Jacques Cousteau once called the oceanic whitetip “the most dangerous of all sharks,” but divers with extensive shark experience tend to have a more nuanced take on the species. Stan Waterman, another diver from the Blue Water, White Death expedition, says part of what made their dive unique was that it allowed them to see how oceanic whitetips actually behave, compared with how they were thought to behave. “It was a great learning experience,” he says, “because we weren’t sure what would happen when we got out of the cages.”
They found the same thing so many of the Indianapolis survivors reported: Whitetips are not shy about approaching and bumping, even repeatedly, but if you stay in a group and fend them off, they’re not likely to attack—at least not when there’s plenty of other food in the water. “We got sussed out hundreds of times,” Valerie Taylor says, “and then they decide you’re not worth bothering about and go away.”
Nine to 13 feet long at maturity, the oceanic whitetip is certainly large enough to be dangerous, and it is a bold and persistent shark. The open ocean is an ecological desert, and oceanic whitetips are geared to spend as little energy as possible exploring it and as much time as necessary investigating the things they come across that might be good to eat. So they glide through the water with their long, winglike pectoral fins, and when they come across a potential food source—sailors flailing around a shipwreck, a dead whale, a school of tuna—they lock in to check it out. If you’re the only food around, the oceanic whitetip is going to be a very dangerous shark. Otherwise, it’s apt to be mostly unnerving.
One of the most interesting anecdotes about the behaviour of oceanic whitetips has nothing to do with shipwrecks or divers, though. In the 1950s, fishery researchers in the Gulf of Mexico were surprised when they opened up the stomachs of whitetips and found five- and 10-pound tuna in them, because the sharks aren’t fast enough to chase down small tuna. Then one day they saw a large group of whitetips swimming through a school of tuna, at the surface, with their mouths open. “No attempt was made by the sharks to chase after or snap at the hundreds of tuna,” the researchers reported. “The whitetips were merely waiting and ready for those moments when tunas would accidentally swim or leap right into their mouths.”
Of course, it’s doubtful anyone would be able to observe behaviour like that now, and the great irony is that the researchers who recorded the spectacle were helping pave the way for its end. “They were out there to see what kinds of commercial fisheries could be developed in U.S. waters,” says Julia Baum, a marine ecologist who compared the data from the 1950s with more recent longline catch data to gauge the change in oceanic whitetip populations in the Gulf. “They were setting out these longlines for tuna, and the sharks were just everywhere,” eating the tuna on the hooks and getting hooked on the lines themselves. “They didn’t know if they’d be able to develop commercial tuna fisheries because the sharks were so numerous.”
The fishermen came up with two solutions: shoot the sharks before they ate the hooked tuna, and set separate lines to catch the sharks, the fins of which, they realized, were worth money. Perhaps enough money to justify catching them. And together, these two forces—a callous disregard for sharks and a growing demand for shark fin soup in Asia—have decimated global shark populations in the past several decades and have taken a particularly steep toll on oceanic whitetips. Baum’s research led her to conclude in 2004 that whitetip populations had fallen by as much as 99 percent in the Gulf of Mexico, and though her study has critics, other research has found similarly dramatic declines in the Atlantic and Pacific.
It became so clear by 2010 that oceanic whitetips were in trouble that the five major international fishery organizations that oversee swordfish and tuna fishing forbade vessels from keeping any oceanic whitetips they caught—the only shark species so far to receive that protection. And in 2013 the Convention on International Trade in Endangered Species (CITES) enacted restrictions that severely curtail legal trade in their fins.
The question is whether the protections are too little, too late. Many bony-fish populations can quickly repopulate after being overfished, because they spawn relatively early in their life cycles and lay thousands of eggs at a time, but most sharks reach sexual maturity slowly and then give birth to small litters of pups every one or two years. These factors make them extremely vulnerable to overfishing and susceptible to extinction. And in the case of oceanic whitetips, “we still don’t even know whether they give birth every year or every two years,” says marine biologist Edd Brooks. “How do you begin to conserve an animal when you have so little information about how it lives its life?”
Brooks is one of the scientists trying to fill in some of those gaps. He’s part of a team of researchers that since 2010 has been tagging and studying oceanic whitetips off Cat Island, in the Bahamas. “Cat Island is the last place we know of on the planet where you can reliably find them in serious numbers,” he says. It was not just the first time he or any of his colleagues had done comprehensive, hands-on research on the species. It was the first time anyone had, anywhere.
A Fortune in Fins
Oceanic whitetips are prized for their large fins. At a Hong Kong seafood market, dried lower caudal lobes can fetch $265 a pound.
First dorsal with its fin needles, lower caudal lobe, and pectoral fins are the best sources of cartilage. Fins have no taste or nutritional
value, but shark fin soup lovers relish the texture of their tiny needles. The estimated population decline between 1995 and 2010 is 93%.
Cat Island is right at the edge of the continental shelf, bringing the deep waters of the Atlantic close to shore and making it a perfect spot to find big pelagic fish such as marlin and tuna. About 10 years ago rumors started to circulate that fishermen off Cat Island were having trouble with oceanic whitetips stealing their catches. Photographer Brian Skerry sensed a rare opportunity and hired a dive operator to help him get underwater shots of the sharks. Their success led to regular dives off Cat Island. Word got out, and scientists got in on the action.
“This was the project we always wanted to do,” says marine biologist Lucy Howey. “We never actually thought it would happen, because we didn’t think we’d be able to find them.”
Howey’s team, which included Brooks and Demian Chapman, tagged nearly a hundred oceanic whitetips with satellite tracking devices, which recorded movement patterns and other data. They made several significant discoveries: First, although the sharks traveled broadly through the Atlantic, they spent much of the year in the protected waters of the Bahamas, where longline fishing was prohibited in the 1990s and a commercial trade ban on all sharks was enacted in 2011. So having protected areas where sharks are free from fishing pressures could be crucial to the restoration of the species.
Second, oceanic whitetips spend 93 percent of their time between the surface and a hundred meters (328 feet), which suggests that early commercial fishing, when tuna and other fish were abundant at those depths, may have taken an outsize toll on the sharks. So regulating fishing in that range could aid conservation.
But the third finding is the alarming one: The population that frequents Cat Island may be as small as 300. After five years of tagging, the high number of individuals being recaptured suggests far fewer sharks inhabit these waters than the researchers initially thought.
Let that sink in: There may have been more oceanic whitetips swarming that whale carcass in Blue Water, White Death in a single day than there are in the course of an entire year at the best known stronghold the species has left.
It’s possible that relatively robust populations exist in other places. Oceanic whitetips are frequently seen in the Red Sea, off the Cayman Islands, and around Hawaii. But sightings in those areas are typically of lone individuals or very small groups, so it’s impossible to make an educated guess about their overall numbers.
Howey says the crucial question now is to find their birthing grounds. The fourth thing her team discovered is that many of the whitetips off Cat Island are pregnant females. But there are no signs that the sharks give birth there. “We’ve never seen pups in the Bahamas,” she says. “If we know where they give birth, we can protect those areas. That’s how we’re going to make headway in protecting the species.”
It is impossible to rewind time, and impossible to recapture lost innocence. The relatively unspoiled seas of the 1950s, full of so many fish that nations were more worried about not making use of the resource than about exhausting it, seem almost incomprehensible now. But Cuba, which stretches like a long bridge from the southern Bahamas to the Gulf of Mexico, may be something of a bridge to a bygone time. The more than 50-year trade embargo imposed by the United States has not just slowed Cuba’s economic development; it has also dampened the exploitation of its natural resources, and as a result the marine preserves off Cuban shores are among the world’s most pristine.
Right now the Cuban government is working on a shark conservation plan. For the past six years Cuban scientists have been taking detailed surveys of the sharks fishermen are catching offshore, and they’re finding something their U.S. colleagues will be happy to hear. On the north coast of Cuba, off the small village of Cojímar, fishermen are catching sharks in droves. The third most abundant species they’re catching: oceanic whitetips. Mostly juveniles, and some of them small pups.