Shark Life: True Stories About Sharks & the Sea Page 4

  Still, there are actions you can take to reduce the odds even further—besides staying out of the water altogether. There are even one or two things you can do to protect yourself if, God forbid, you ever are attacked by a shark. More about both later.

  Each of the following statements about sharks has been printed, reprinted, and guaranteed to be the absolute truth. Of the three, which one would you say is true?

  1. Of the 380 species of sharks known to science, fewer than a dozen pose any threat whatever to human beings.

  2. Of the more than 400 species of sharks in the world, only 11 have ever been known to attack a human being.

  3. Of the 450 species of sharks on record, only 3 qualify as man-eaters.

  Don't bother to guess—it's a trick question. The answer is: none of the above. To begin with, nobody knows for certain how many species of sharks there are. Scientists can't agree on how many different species have been discovered and cataloged. Some sharks go by different names in different countries. Australia's gray nurse shark, for example, bears no resemblance to the nurse sharks of the Atlantic and the Caribbean. In some countries, some subspecies are identified as separate species. Most scientists believe that the Zambezi shark and the Lake Nicaragua shark are both bull sharks; a few disagree. Some experts insist that Carcharodon megalodon, the fifty-foot monster that roamed the seas thirty million years ago, is a direct ancestor of today's great white shark. Other experts insist that today's makos are the true descendants of C. megalodon.

  Another reason we don't know precisely how many species of sharks there are is that new sharks—new to humans, that is—are still being discovered. In 1976 a behemoth almost unknown to science, nearly fifteen feet long and weighing three-quarters of a ton, was caught accidentally by a U.S. Navy ship off Hawaii. A plankton feeder with an enormous mouth, it was dubbed megamouth. A dozen other specimens have since turned up, everywhere from Japan to Brazil. In 1990 one was filmed swimming free, after it had been released from the net that had caught it off California. For all its size and heft, mega-mouth is slow, curious, and not at all aggressive.

  More new species of sharks will probably appear as, little by little, we and our miraculous technology turn our focus toward the sea. At least I hope we will, for our record so far has been nothing short of disgraceful.

  We have seen less than 5 percent of our oceans; humans have actually visited less than 5 percent of that 5 percent.

  We have studied the ocean so little compared to the earth that it's as if we dragged a butterfly net behind an airplane over the Grand Canyon at night and, based on what we collected, developed theories and generalizations about life on earth.

  Here are some facts: nearly three-quarters of our home planet is covered by seawater (of an average depth of two miles); there are mountain ranges in the ocean higher than the Himalayas; there is enough gold suspended in seawater to supply every man, woman, and child on earth with a pound of the stuff; we can't even calculate how valuable the mineral, nutritional, and medicinal resources available in the sea might be. And yet for the past half century we have devoted much of our national treasure to reaching and studying a moon that we know to be barren, while spending, relatively, pennies on exploring our own oceans. More than forty years ago President John F. Kennedy was already lamenting that we knew more, even then, about the far side of the moon than we did about the bottom of the sea.

  We know almost nothing about the ocean, so it's not surprising that we know so little about sharks.

  Until recently, there's been no encouragement to learn about sharks, for sharks have never been popular. Whales, on the other hand, are enormously popular. The save-the-whales movement is more than thirty years old. And dolphins, of course, have long had large groups of devoted advocates.

  It's true that whales and dolphins are easy to study and easier still to love. They're mammals. They breathe air. They nurse their young and guard them ferociously. They click and talk to one another. They do tricks. They're smart. We can project human characteristics onto them. We give them names and convince ourselves that they respond to—and even love—people they come to know.

  Not sharks. Sharks are hard to study and harder still to love. Because they're fish, not mammals, they don't have to come up for air, so they're difficult to keep track of and impossible to count.

  And they do have the unfortunate reputation of occasionally—very, very occasionally—attacking a human being. And—even more rarely—of eating one.

  It's hard to care deeply for something that might turn on you and eat you.

  Traditionally, shark scientists have been highly educated in the library and the laboratory and underexperienced in the field. But there have been—and are still—a handful of outstanding, dedicated shark scientists. They are rich in talent and widely experienced in the field.

  Jaws brought me a lot of benefits, but the one I value most is the chance to do television shows and magazine stories with, and learn from, the scientists, sailors, fishermen, and divers who make the sea their home. The knowledge we've gained since the mid-1970s has convinced me that almost all of the great white shark behaviors I described in Jaws do happen in real life. But I'm also convinced that almost none of them happen for the reasons I described.

  For example, what I and many others thought were attacks by great whites on boats were really explorations and samplings. In 1999, in the waters off Gansbaai, South Africa, I witnessed great-white behavior that would have been unimaginable even a few years before. Large adult great whites approached our tiny outboard-motor boats and permitted a “shark wrangler” named Andre Hartman to cup his hand over their snouts—a risky business. They rose out of the water, gaped for several seconds as if hypnotized, then slipped backward, down and away, in what looked like a swoon.

  I am now convinced that attacks on human beings, which I had thought were intentional, were mostly cases of mistaken identity. Sharks had been condemned as man-eaters for thousands of years, and it would be several more years before that belief would be effectively challenged.

  We knew so little back then and have learned so much since, I couldn't possibly write the same story today. I know now that the mythic monster I created was largely a fiction.

  I also know now, however, that the genuine animal is just as—if not even more—fascinating.

  Most shark behaviors, it turns out, are explainable in logical, natural terms.

  Sharks are critically important to the health of the oceans and the balance of nature in the sea. Later I'll go into detail about why I believe we should appreciate, respect, and protect sharks, rather than fear them.

  First, though, let's take a look at some of the most dangerous sharks—the ones that have been called man-eaters.

  7

  Six Dangerous Sharks

  There are, I believe, half a dozen species of sharks that can, and sometimes do, pose a threat to human beings.

  THE GREAT WHITE

  First and most notorious is the great white, the shark portrayed in Jaws. Great whites are the largest carnivorous fish in the sea. They can grow to be more than eighteen feet long and can weigh more than four thousand pounds. They can, and sometimes do, eat people, though it's now accepted that nearly every attack on a person is a mistake. The shark might confuse the person with a seal or sea lion. Or, particularly in murky water, where it must rely on senses other than vision, the shark takes a test bite to decide if this living thing is edible. There have been cases of great whites targeting humans. Few though they are, each case generates real horror.

  A few years ago a woman who had been scuba diving near a seal colony was attacked in the waters off Tasmania. She had almost gotten to the boat and was reaching out to grab her husband's hand when an enormous great white attacked her from behind and below. While her shocked husband held her hand, the shark bit her in half. Then it returned and took the upper half, literally yanking her torso from her husband's grasp.

  Another notorious episode—and one for wh
ich no shark expert, scientist, or diver I've spoken with has ever offered a good explanation—occurred back in 1909. A fifteen-foot-long female great white was caught in the waters off the town of Augusta, Sicily. In her belly they found the remains of three human beings: two adults and a child.

  More than 70 percent of victims of great-white shark attacks survive because the shark realizes it has made a mistake and doesn't finish off the prey. Granted, that figure doesn't take into account swimmers, divers, and snorkelers who simply disappear while swimming in great-white country.

  The high rate of survival may have to do with something known as the “bite, spit, and wait” theory of great-white behavior. This theory was first advanced by Dr. John McCosker, senior scientist at the California Academy of Sciences. It explains both fatal attacks and attacks that end after a single bite. According to McCosker, great whites can tell in the microsecond of a first bite whether their potential prey has enough calories to be worth the effort. That is, if the prey won't deliver as much energy as the shark will use up in attacking and eating it, the shark breaks off the attack after a single bite. Depending on how serious that first bite is, the prey may or may not live to tell about it.

  But if the first bite tells the shark that the prey contains a lot of energy—if it's a nice fat seal, for example, or a sea lion—it will hang around after the first bite. Then it will wait for its prey to bleed to death before it comes back to finish the meal.

  In general, large great whites perceive human beings as too bony to bother with. So they often leave after that first bite. Of course, when a 2,000- or 3,000-pound fish tastes a 170-pound man, even one bite can be fatal. I will never forget a coroner's photographs of a young man killed in the Neptune Islands off South Australia. The shark must barely have grazed him before recognizing its mistake. Aside from one deep cut in a thigh and a nasty wound on one hand and wrist, the victim was unharmed. In the photographs he looked as if he was asleep. Sadly, however, the big shark's big teeth had opened two arteries, and the man had bled to death before he could reach the shore.

  Some white-shark victims insist that they felt no pain at all when they were attacked, only the impact as they were struck. Then they felt a tug as the shark's scalpel-sharp teeth severed flesh and bone. My wife and I have a friend who lost a leg to a white shark while snorkeling off Australia. He said, “I couldn't see it, but I knew exactly what had me. It had me by the leg and was pulling me down. I thought for sure I was going to drown. I've never been so relieved in my life as when I felt my leg let go.” Luckily for him, a boat was nearby. Someone aboard knew how to tie a tourniquet around his thigh, and he made it to a hospital.

  From the swimmer's perspective, the best thing about great whites is that although they exist worldwide, they're extremely rare. Great whites are an apex predator, meaning they are at the top of the food chain. They are too powerful and devastating to exist in vast numbers: the marine food chain couldn't support them. So great whites breed late in life—not until they're at least twenty years old. And they bear very few young, only some of which survive to adulthood.

  TIGER SHARKS

  Tiger sharks, too, are genuinely dangerous to humans. They've been responsible for several attacks off Hawaii in recent years. On October 31, 2003, thirteen-year-old Bethany Hamilton, a top amateur surfer, was surfing with her best friend off the island of Kauai when a tiger shark bit off her left arm just below the shoulder. Her friend's father used a surf leash as a tourniquet to stop the bleeding; then fellow surfers put her on another surfboard and paddled her to shore. Their quick actions no doubt saved Bethany's life.

  It's widely believed, with good reason, that tiger sharks pose more of a threat to humans than do great whites. Tigers may not be as big or as heavy as great whites, but a fifteen-foot, fifteen-hundred-pound tiger shark is plenty big enough. There are more of them, for they bear many more young than great whites (though sometimes the greedy young quickly eat each other). And they're everywhere. While great whites, as a rule, hang around coastal waters, tiger sharks are completely free-roaming. They're fond of coastal waters, and they like to enter lagoons at night and hunt in the shallows for prey that often includes smaller sharks. They also roam the deep.

  Once, when I was on a boat over the abyssal canyons off Bermuda, a huge tiger shark cruised leisurely around our stern, as if showing off its amazing size. The top of its head was as big around as a manhole cover. The long, slender striped body seemed to take forever to pass by the stern. It was a chilling sight that reminded me of the crocodile in Peter Pan that waits for Captain Hook to fall overboard. To me, the message from this giant was Take your time; no rush. I'm in no hurry. But sometime, someday, one of you will make a mistake and enter my realm, and then you'll be mine.

  Suddenly, though, the shark must have sensed that real potential prey was nearby. It sped away and a few seconds later exploded through the surface fifteen or twenty feet behind the boat. Clutched in its jaws was an adult sea turtle. The turtle was too big to swallow, and its shell was too tough to crack. It had pulled its head and legs into the safety of its shell. The shark shook the turtle violently from side to side. Then, mysteriously, it let the turtle go and slipped silently beneath the surface.

  For several moments we watched the turtle bobbing on the surface, head and legs still invisible. We guessed that the shark had given up and gone in search of easier prey. The turtle must have decided the same thing, for slowly its legs protruded from the shell, then came the head, and then …

  Bammo! Like a rocket the shark blasted up from below. It clamped its jaws on one of the turtle's hind legs and didn't let go until the leg came off. The remaining three legs and the head snapped back inside the shell. Again the shark slid away underwater; again the turtle bobbed on the surface.

  For the next half hour or so, we saw the attack repeated again and again, though without any more success. Once wounded, the turtle seemed ready to hunker down inside its shell forever, if necessary. As much as we rooted for the turtle—we knew it could live a successful life with three functioning legs—there was no way we could interfere. Nor did we want to, for this was normal, natural predation in the sea.

  BULL SHARKS

  The third shark that poses a true threat to humans in the sea is the bull shark. Bull sharks come in several varieties, including the Zambezi shark, the Lake Nicaragua shark, and several of the so-called whalers of Australia. As the first two names imply, bull sharks are even more wide-ranging than tigers. They have been found in—and have killed people in—lakes and rivers. Most sharks can't survive, not to mention hunt and feed, in brackish water. But bull sharks can function normally in salt, brackish, and fresh water.

  Bull sharks are common in shallow water and murky water, like that off the Gulf Coast of Florida. It was a bull shark that attacked young Jesse Arbogast in July 2001, triggering the media frenzy that lasted all summer. And bull sharks were probably the culprits in the two nonfatal attacks a month later in the shallow waters off Grand Bahama Island. Bull sharks have such a bad reputation for being aggressive, fearless, and territorial that they undoubtedly are blamed for more attacks than they're responsible for. Still, there are so many bull sharks in so many waters in which so many people choose to swim that they must be classified as extremely dangerous.

  OCEANIC WHITETIPS

  Then there's the oceanic whitetip. Its Latin name describes the creature so perfectly that I'll burden you with it: Carcharhinus longimanus, or “long-hands.” This shark's pectoral fins are extraordinarily long and graceful. They look like the wings of a modern fighter jet. Longimanus tends to stay in the deep ocean. Nobody on earth has the vaguest notion about total numbers of long-hand attacks. That's because the people they do attack are either adrift, alone, or survivors of shipwrecks, who don't much care what species of shark it is that's harassing them.

  I do know, however, that longimanus is unpredictable, scary, and capable of killing a human. There's a story about one that attacked two U.S. Navy
divers in the deep waters of the Tongue of the Ocean in the Bahamas. The shark took a big bite out of one of the divers. Then, as the diver's buddy tried to hold on to his friend, it dragged the diver into the abyss. Finally, at a depth of about three hundred feet—far beyond safe scuba depth—the buddy had to choose between letting go of his friend and dying himself. He watched as shark and body disappeared into the gloom.

  Long-hands are one of the few species of shark that genuinely terrify me. A couple of decades ago one made an honest effort to eat me. I don't blame the shark for trying, because my situation fell well within the bounds of Stupid Things You Should Avoid at All Costs. But the near miss still scared me—and scarred me permanently.

  I was with an ABC-TV crew, also in the Tongue of the Ocean, in open water more than a mile deep. We had tied our boat to a navy buoy. The buoy had become a popular spot to film because it had been in the water for so long that the sea had claimed it, transforming it into an artificial reef. Microscopic animals had taken shelter in the buoy and the chain and had been followed by tiny crustacea and other small critters. Then larger and larger creatures had come to feed. Finally—in the magical way the sea has of generating life on all levels—the entire food chain had come to use buoy and chain as a feeding ground.

  A school of yellowfin tuna was swarming around the buoy, attracted by something. In the brilliant sunlight of the summer day the colors were gorgeous. So we decided to take some footage for the film segment about the Bahamas that we were working on for The American Sportsman.