River Monsters

by Jeremy Wade

  Maybe they’ll even wait us out, like they did the dinosaurs.

  THE AMAZON LAKE MONSTER that nobody believed was real, including me—until I took this picture. This is the reason I don’t automatically dismiss other fishermen’s tales.

  IN MY EARLY TWENTIES I was an obsessive carp angler, escaping whenever possible to camp beside English lakes.

  THERE’S MORE TO some fish than meets the eye. Carp have powerful teeth in the back of the throat that would crush a finger just as soon as a snail shell.

  A FIFTY-EIGHT-POUND MAHSEER, which dragged me down rapids on the Kaveri River in South India on my thirtieth birthday. Local handline fishermen have been nearly drowned.

  IN ZAIRE (now Democratic Republic of Congo) in 1985 I traveled on one of the legendary giant riverboats—with two thousand other passengers, uncounted stowaways and secret policemen, and trussed live crocodiles.

  ZAIRE VILLAGE CHILDREN show me a standard-issue, striped (not goliath) tigerfish. Its feared larger cousin, they told me, can almost bite a person in half.

  LEFT: PEOPLE’S REPUBLIC OF CONGO, 1990. When I took this picture I was incubating a near-fatal dose of malaria.

  MY FIRST TEACHER of Amazon jungle-craft. Hard-as-nails José fishing with gillnets on Lago Grande.

  BECAUSE OF THEIR GREAT WEIGHT, fishermen butcher arapaima at the lakeside. Mostly you just see their huge, kipperlike fillets.

  FISHERMEN SELLING THEIR CATCH on the waterfront at Manaus. The amount of commercial fishing in the Amazon truly shocked me.

  REVISITING THE SCENE of my Amazon plane crash. Only weeks later did I realize how close I’d come to dying.

  THE FISH THAT HIMALAYAN VILLAGERS say is a man-eater. My capture of this 161-pound goonch, after plunging after it into monsoon floodwater, gave weight to their stories.

  BREATH-HOLD DIVING IN UNDERWATER CAVES in a cold, cloudy Himalayan river with trailing poachers’ lines was not my idea of fun. But we did, eventually, get the first-ever footage of goonch in their natural habitat.

  THIS CUIU-CUIU OR “RIPSAW CATFISH” was a rare catch. But this armor didn’t stop a piranha from taking a mouthful out of its back on the way to the boat.

  THE BUSINESS END OF A PIRAIBA, one of two catfish species that Amazon fishermen say have swallowed people whole.

  WITH A CHAINSAW-LIKE SNOUT on a shark’s body, sawfish require careful handling.

  LIKE AN ALLIGATOR WITH FINS. But is the much-maligned alligator gar as dangerous as it looks? And how reliable are the reports of fourteen-footers?

  GIANT GROUPERS have been known to attack divers by grabbing arms, legs, and, even once, a man’s head. But this 250-pounder from a river surprised even local fishery experts.

  BLEARY-EYED DAYBREAK ON THE BRISBANE RIVER. Not such a good time for darkness-loving bull sharks, but at least you can tell if that’s an oil tanker you just hooked.

  GET STABBED BY THIS SPINE, with its coating of toxic slime, and the pain is like holding your foot in a fire. Death can follow from gangrene or blood loss.

  CAUGHT WITH A LINE BUT NO HOOK, the longfin eel is an unlikely man-eater—until you piece together its grisly modus operandi.

  THE TWO THOUSAND–MILE RIO PURUS was my second home for nearly ten years. On its way to join the Amazon, the Purus is a confusion of bends and hidden backwater lakes. Annual floods raise the water level by up to fifty feet.

  THE DJOUÉ RAPIDS, where the Congo River squeezes down to just 1,200 yards. Further downstream it’s 350 yards. Surely an insane place to cast a line.

  “HE CRIED IN A WHISPER at some image, at some vision ... ‘The horror! The horror!’” (Joseph Conrad, Heart of Darkness, 1902).

  THE FISH THAT TOOK TWENTY-FIVE YEARS to catch.

  CHAPTER 10

  FRESHWATER SHARK

  Unique, then, but not beautiful. Its jaw is wider and squarer than any other, its incisors proportionately more fearsome, its eyes tiny, since sight, in turbid waters, need not be perfect. And those purblind eyes stalked this river: steel ball-bearing eyes, set deep in the side of its skull.

  Edward Marriott, Wild Shore, 2000

  MIAMI LAKE WAS NOTHING LIKE I EXPECTED. I had pictured a wild place, fringed with reeds, the houses far from its shore. But Australia’s Gold Coast is not like that; instead, it’s a high-density development where trimmed lawns go right down to the water. Originally a swamp, the area was developed in the 1950s and now comprises more than 150 miles of canals that are crowded with condos and boat jetties—a supreme embodiment of the popular idea that water is a place of fun and leisure.

  Looking at the lake’s bright surface, I had difficulty reconciling what I saw with the newspaper reports. They reported that here, in December 2002, a twenty-three-year-old man had gone for a cooling dip at night with a friend and then had disappeared. His body was found three days later, showing the unmistakable marks of a shark attack. From what a lakeside resident told me, the two men had set out to cross a narrow neck where the water is shallow, but in the dark they got separated and the victim strayed into the main body of the lake, where there is a steep drop-off close to the edge. A few weeks later, while locals were still consoling themselves with the fact that this was a freak event, an eighty-four-year-old early-morning swimmer suffered a fatal shark bite to his leg in nearby Burleigh Lake. The police brought in netsmen from Queensland’s offshore shark control program, and they then captured three female bull sharks (Carcharhinus leucas) ranging from five feet to seven feet, four inches, but none contained any human remains.

  From Miami Lake to the sea, by way of the canals, is about ten miles. Although inland, the waterways are tidal, but sluice gates partially restrain the outgoing tide in order to prevent the picturesque green borders from extending to mud. When the sluices are open, however, any fish with a body up to four feet deep could, in theory, pass through. Authorities reckon there are hundreds of bull sharks in the canals. In fact, one man fishes for them from the balcony of his sixth-floor apartment, overlooking Lake Orr. He says in eighteen months he has caught twelve and lost around eighty. To land them, he sends his friend running downstairs with a gaff.

  Normally we don’t need a physical barrier to prevent sea fish from moving inland. The transition from salt to fresh water is a barrier in itself, as secure as any metal grill. This is because, in order to take up oxygen, fish have a convoluted expanse of thin membrane, the gills, in intimate contact with the surrounding water. But this semipermeable membrane (whose microscopic pores allow the passage of small molecules but not large ones such as salts) also allows the passage of water. The direction of this movement depends on whether the surrounding water is more or less salty than the fish’s tissue fluids. In fresh water, water molecules diffuse inward; in sea water they diffuse outward. For this reason, freshwater and sea fish have fundamentally different strategies for keeping their body fluids at the correct concentration. Freshwater fish must constantly excrete the surplus water they take in; sea fish must constantly replace lost water by drinking. (The salt contained in the seawater that sea fish drink is actively removed from the body by special cells in the gills.)

  A freshwater fish dropped in the sea would, therefore, experience runaway water loss, whereas a sea fish placed in fresh water would become waterlogged, its cells exploding from increased osmotic pressure.

  Even brackish water, the zone where the water is neither fresh nor salt, is uncomfortable for most fish. Most sea fish can’t tolerate the half-andhalf mixture of salt and fresh that sluices the inland waterways of the Gold Coast. So the presence of sharks here appears to offend the laws of nature as well as our sensibilities. In fact, sharks are the last sea fish you would expect to find inland because their tissue fluids are even more concentrated than those of other fish. This is because they retain certain waste products in the body, specifically urea and trimethylamine oxide (TMAO), to the point at which their bodies are marginally more “salty” than the surrounding sea water. This allows water to gently diffuse in, with low-level excretion removi
ng any surplus. This increased internal saltiness is a near-perfect adaptation to living in the sea, but a shark transferred to fresh water would experience an even greater shock to the system than its less well-adapted marine brethren: an inrush of water that would demand very high-volume excretion to counteract it—like frantically baling a holed boat to stop it from going under.

  So how do bull sharks manage to break the rules? And they’re not just in the Gold Coast canals but also in estuaries and rivers worldwide where these are accessible from the warm coastal shallows where bull sharks are normally found. In 1993 I wandered into a gloomy shop in Manaus, where the Rio Negro meets the Amazon, looking for rope and tarpaulins. Hanging from the ceiling were several stuffed fish, dark brown with age and varnish, the biggest of which, thick bodied and seven feet long, I at first took to be a piraiba, the Amazon’s giant catfish. The general body shape was about right, but closer inspection revealed an asymmetric tail and five parallel gill slits. The shop’s owner told me that one of his employees, now dead, caught it from a spot just downriver. This bull shark had been nine hundred miles from the sea, and there are other reports from near Iquitos, in Peru, more than two thousand miles inland. A fisherman I met later told me he’d caught four or five in the ’60s and ’70s on long lines set for catfish. Another man told me he’d seen one in the ’80s when he was working at the fish-freezing plant in Iranduba near Manaus, where many fishing boats unload their catch. “They called everyone to see it. It had no scales, like a catfish,” he said. “When you moved your hand down its body toward the tail, it was smooth. But in the other direction it was rough, like a file.”

  More recently, in a bar in Zambia, I saw some jaws with broad-based serrated teeth in the upper jaw (for cutting, like steak knives) and narrower, more pointed teeth in the lower jaw (for gripping). People originally thought the “Zambezi shark” was an endemic species, but now we recognize it as the same species as the Ganges shark and the Lake Nicaragua shark, not to mention the bull sharks that have been found in US rivers. These include an eighty-four-pounder that two commercial fishermen, Herbert Cope and Dudge Collins, from Alton, Illinois, caught in 1937 1,750 miles up the Mississippi. Something had been chewing through their wood-and-mesh fish traps, so they set a wire one baited with chicken guts. Although some dismissed this as a hoax, this catch is now widely considered to be authentic, although bull sharks would now find dams blocking their way. In addition, three of the five notorious Jersey Shore attacks of 1916, which inspired Peter Benchley’s 1974 novel Jaws and the subsequent Spielberg film, were likely the work of bull sharks, not a rogue great white as originally concluded. Even though the attacks stopped after the capture of an eight-foot great white in Raritan Bay, reportedly with human remains in its stomach, the last three attacks were up the narrow Matawan Creek, which would be a very unusual habitat for a great white. And subsequent newspaper stories refer to other sharks seen and captured in the creek after the alleged culprit was killed. More recently, a reported attack in Lake Michigan was almost certainly a hoax, but they have been reliably identified in inland Louisiana.

  The fact that the very shark species that swims into rivers just happens to be the one that’s the most dangerous to humans, more so than hammerheads, tiger sharks, and even great whites, appears to be a very cruel irony. But this is no coincidence: the reason bull sharks have attacked more people than other sharks is precisely because they live so close to humans in shallow coastal waters, estuaries, and sometimes rivers. Compared with where other sharks live, this water is often murky, so identifying objects or other animals is difficult for their small eyes. Not having hands, fish often feel with their mouths. Rory McGuinness, our cameraman on this shoot, once had his kayak bumped by a bull shark while he was paddling in the Gold Coast canals. So the bull shark’s “aggression” is likely sometimes simply curiosity or even self-defense when a swimmer inadvertently gets too close, although this doesn’t make them any less dangerous.

  The bull shark’s ability to penetrate fresh water is thanks to a quirk of physiology that is unique among large sharks. When entering fresh water, bull sharks are able to reduce the saltiness of their tissue fluids by about a third. They do this partly by excreting salt via their rectal gland. Studies have also found that the concentration of urea in their tissues drops by more than 50 percent. Despite this, however, their body fluids are still more than twice as salty as those of typical freshwater fish, so they need to increase their rate of excretion to get rid of surplus water. Experiments suggest that they excrete more than twenty times the volume of water than they do when in the sea. This increased workload on the kidneys requires the expenditure of more energy, so by the mathematics of biological accounting, which all creatures unconsciously carry out, there must be some benefit to offset this cost in order to make moving into fresh water worthwhile. The question is: what?

  One advantage of fresh water is fewer predators, especially other shark species, to prey on bull shark pups. This tallies with the fact that river mouths and estuaries tend to be used as bull shark nurseries. The choice of estuaries, rather than completely fresh water, is interesting and is probably a compromise based on a weighing of pros and cons. Despite the bull shark’s tolerance of fresh water, small bull sharks have a harder time in a river, water balance–wise, than large bull sharks. This is thanks to the geometry of growth: small animals have a higher surface area to volume ratio than their larger brethren. And with more surface area per unit of body mass, they take in water more readily and hence need to get rid of it faster. So stick to the estuary, where predators are few and energy costs are not too high—the ideal combination.

  But why adult bull sharks, apart from gravid females, are in rivers is less certain. Maybe it’s simply because they can, and they wander back and forth on a whim. The biggest bull sharks I’d heard of in this part of Australia were in the Brisbane River, further north up the coast. In 2007 Terry Hessey caught a nine-foot, six-inch specimen at the mouth of the river, which pulled 440-pound scales to their limit and was estimated at well over 500 pounds. This was identified as a gravid female by virtue of its distended abdomen (adding to the general stockiness, which gives the bull shark its name) and the absence of penislike claspers on the underside of the body.

  The bull shark pups, up to a dozen of them, are born a year after fertilization. Shark scientist Dr. Richard Pillans estimates that there are two to five thousand juvenile sharks in the Brisbane River—so many, in fact, that local anglers hold an annual shark-fishing competition. Terry caught his monster during this event. And although I’d seen a picture of this fish, beached in tidal shallows, I needed to see one in the flesh. Despite knowing about the bull shark’s osmoregulatory bag of tricks, the idea of a shark in a river was still something to get used to, as it is for most people.

  So I met up with Terry and his fishing buddy Ben Cole at a place called Luggage Point, which even at night has to be one of the least picturesque fishing spots I’ve ever been to, although this in itself makes it stand out in the memory. The place is known informally as the “poop shoot” because it is the site of a huge sewage treatment plant that perfumes the air and the intertidal mud. But fish have different sensibilities from humans, and the peculiar water quality here likely attracts them, from small bottom feeders right up the food chain. Terry had gotten a hold of a couple of good-sized freshwater eels, about as thick as my wrist and three feet long, which are a favorite meal of bull sharks, along with stingrays. Bull sharks are mainly bottom feeders, and because they often feed in cloudy water, they don’t rely much on eyesight to find food—hence their small eyes. But they are far from blind in the water thanks to a sixth sense that humans don’t possess. On a bull shark’s snout are pores known as the ampullae of Lorenzini, which are sensitive to minute electrical currents, such as those produced within the body of a prey animal. The effectiveness of this sense has been most clearly demonstrated in hammerheads, which sweep their ampullaerich heads over the bottom like a metal detect
or, locating buried stingrays that are otherwise invisible.

  But this super sense makes things difficult for shark anglers because metal leaders, crimps, and hooks create electrical microcurrents, thus advertising their presence in the water. In an attempt to make his leader invisible to bull sharks, Terry was using PVC-coated wire rope as leader material, the thickness of washing line and with a breaking strain of 1,300 pounds for bite-resistance. He wrapped the hooks with plastic insulating tape, except for the very points, which he gave a final few strokes of the file before rigging the baits—a small touch that marked Terry as somebody who knew what he was doing. Bait rigging was equally meticulous, with cable ties holding the 16/0 hooks firmly in position with their points well exposed. Meanwhile Ben was filling a large cloth bag with several pounds of sand and tying it closed with a length of 40-pound mono, which was then tied to the swivel at the top end of the leader. Casting this assemblage of weighted metalware was of course out of the question, so Terry now hopped into his kayak with the bait and sandbag and set off toward the brightly lit wharves, cranes, and moored ships on the other side. After a few moments we lost sight of him, but the big reel continued to spin out line, about two hundred yards of it, until it went quiet and we saw a light flash out on the water. Then the reel’s clicker made a final rasp as the sandbag plummeted to the bottom. As Terry returned, we slowly tightened the line, taking up the slack until the rod, vertical in its metal holder, took on a slight bend at the tip. Then the drag was engaged, just enough to counter the push of water but no more, and the trap was set. After repeating the procedure with a second rod, we settled in to wait.