‘Many scientists​ don’t like to talk about shark sex,’ Juliet Eilperin writes in her entertaining study of sharks and their world. ‘They worry it will only reinforce the popular perception that these creatures are brutish and unrelenting.’ In as far as we understand the subject – only a few species have been observed mating – the business is ‘very rough’. Larger male sharks have to bite or trap the females to keep them around during courtship; marine biologists can tell when a female has been mating because her skin will be raw or bleeding. The process is so violent that, come the mating season, female nurse sharks will stay in shallow water with their reproductive openings pressed firmly to the sea floor. Otherwise they risk falling prey to roaming bands of males who ‘will take turns inserting their claspers in her’ (the clasper is the shark version of a penis, found in a pair behind the pelvic fins). A litter of fifty pups will have anything from two to seven fathers. But the reproductive story gets rougher still. A number of shark species go in for oophagy, or uterine cannibalism. Sand tiger foetuses ‘eat each other in utero, acting out the harshest form of sibling rivalry imaginable’. Only two babies emerge, one from each of the mother shark’s uteruses: the survivors have eaten everything else. ‘A female sand tiger gives birth to a baby that’s already a metre long and an experienced killer,’ explains Demian Chapman, an expert on the subject.

This vignette highlights two themes of Demon Fish: first, marine biologists’ defensiveness about sharks, which they believe get an unfairly bad press. And second, the creatures’ failure to behave in a sympathetic, anthropomorphically pleasing fashion: the idea that they are ‘brutish and unrelenting’ goes way beyond perception. You would have thought it was a category error even to worry about it. They are carnivores, and the ones we’re most fascinated by are the most rapacious predators, right up at the top of the food chain. But the defensiveness is understandable. Fear and hatred of sharks are powerful forces, despite, as Eilperin puts it, ‘the modest threat they pose to us, and the grave threat we pose to them’. In general, human attitudes towards sharks, or at least Western attitudes, are fairly hysterical. The professional shark-hater and shark-killer Captain William E. Young remarked in his 1934 memoir Shark! Shark! that the very word summons up a powerful mental image of

a cold-blooded rover of the deep, its huge mouth filled with razor-sharp teeth, swimming ceaselessly night and day in search of anything that might fall into the cavernous maw and stay the gnawing hunger which drives the rapacious fish relentlessly on his way … There is something particularly sinister in a shark’s appearance. The sight of his ugly triangular fin lazily cutting zigzags in the surface of the sea, and then submerging to become a hidden menace, suggests a malevolent spirit. His ogling chinless face, his scimitar-like mouth with its rows of gleaming teeth, the relentless and savage fury with which he attacks, the rage of his thrashing when caught …

And so on. Yet shark attacks are an exotic rarity. There were 75 verified shark attacks last year, and 12 fatalities. Even in the US, a global hotspot, you are forty times more likely to be hospitalised by a Christmas tree ornament than by a shark. Meanwhile, to supply the shark fin soup trade alone, an estimated 73 million sharks are killed each year. Many shark populations have declined by 70 per cent or more in the last thirty years. One reason little is done about this is that although their fins fetch high prices, shark fisheries are of negligible economic value compared to, say, tuna or cod or herring, so little is done to protect stocks. And then of course humans tend to make more of a fuss over animals we can relate to – because they stand on two legs or live in charming family units, or are unthreateningly charismatic. One of the recent PR successes of the shark conservationists is the ‘walking shark’, which crawls along the sea bottom on its fins and has an appealing little face. The best-protected species are the big, peaceful filter feeders, the basking shark and particularly the whale shark, with its photogenic polka dots and mysterious long-range migration patterns. But we’re gradually becoming more enlightened. The third best-protected species is the great white, described approvingly here by E.O. Wilson as ‘one of the four or five last great predators of humanity’.

Eilperin, an environmental reporter for the Washington Post, has travelled the world trying to understand sharks and human interactions with them. She has swum with reef sharks in the Caribbean and whale sharks in the Gulf of Mexico; she has cage-dived with great whites off South Africa. She has quizzed the shark callers of Papua New Guinea, the shark paste manufacturers of Japan, and the shark fin wholesalers of Hong Kong. She covers shark biology, shark fishing and conservation, shark lore, human attitudes to sharks and, of course, shark attacks. As is the way with popular science writing, Eilperin conveys much of the detail through encounters with the experts, such big hitters of the shark world as Barbara Block, ‘the unquestioned queen of shark tagging’; the lemon shark maestro, Sonny Gruber; Boris Worm, doyen of fisheries conservation ecology; and Jeffrey Carrier, who has, ‘most likely, viewed more shark sex than any other researcher in the world’. Each of these people, as the convention requires, is given a perky little pen portrait: ‘Maclean is a blunt-spoken, stocky bleached blonde who’s spent years taking on the fishing boys’ club.’ Eilperin zigzags shark-like through her material in an intelligent and eccentric way, enlivening it all with occasionally bizarre claims: ‘Europeans like eating shark,’ she says at one point, ‘both as an elegant entrée and as the more plebeian offering of fish and chips.’ (But it’s true: ‘rock salmon’ in Britain, or ‘saumonette’ in France, is spiny dogfish, once one of the most abundant shark species in the world and now critically endangered in the north-east Atlantic.)

Personally, I’ll read pretty much any old rubbish about sharks and absolutely anything about shark attacks. We shark enthusiasts are usually caught between news reports, stupid websites (‘Aquarium Worker Bitten on Face by Shark!’) and the scientific stuff, which can be dry. I have, for instance, spent many happy hours on the Florida Museum of Natural History’s wonderful International Shark Attack File site, but I’ve always felt that it could do with a bit more colour. Those two (unprovoked, non-fatal) shark attacks in British waters recorded between 1847 and 2011, for instance: I’d like to know a bit more about them. When? Where? What kind of shark? (Eventually you discover that one involved a porbeagle shark – the great white’s poor North Atlantic cousin – and a diver. But that’s all they tell you.) So Demon Fish, a book-length exposé of ‘the hidden world of sharks’, is mostly a dream come true. It also has a brilliant cover: a terrifying photo of a grinning great white – with ogling chinless face, scimitar-like mouth, rows of gleaming teeth etc – claustrophobically framed so that it seems to be advancing down a watery corridor towards the reader.

The natural history is pretty amazing. Sharks are cartilaginous fishes (they have a skeleton made of cartilage, not bone) of the sub-class elasmobranchii, which also includes rays and skates. There are more than four hundred species, ranging from the dwarf lanternshark (about 15 cm) to the whale shark, the biggest fish in the sea (‘Max: possibly 1700-2100 cm’, according to my Princeton Field Guide to Sharks of the World). They are very, very old: fossilised species that lived 150 million years ago are almost identical to modern sharks. Sharks were swimming the seas before our continents took shape, while the dinosaurs were still around; Homo sapiens’s 200,000 years are, in the shark’s sight, but an evening gone. Until recently, we knew strikingly little about them. We’re still hazy about such basic matters as how long they live, but research has been revolutionised by genetic testing and electronics. Reports of miraculous ‘virgin births’ to female sharks isolated from males in aquariums, for instance, have recently been explained: genetic sampling shows that sharks are capable of parthenogenesis, or asexual reproduction, in cases where sexual reproduction isn’t possible.

Sophisticated shark tagging techniques and ‘crittercams’ attached to the animals have also explained a great deal about their behaviour. It was discovered that the white sharks of the north-east Pacific (real shark types don’t call them great whites – I imagine they regard the term as vulgar and sensationalist) go on predictable yearly migrations, like antelope or songbirds. In winter they leave the California coast and head out thousands of miles to Hawaii. In August, they return to congregate at ‘hub spots’ off the California coast, including one just off a popular beach near Monterey. In between they go to the ‘White Shark Café’, a remote, empty area halfway between Baja California and Hawaii, where they socialise with other sharks and make frequent, unexplained dives as far down as a thousand feet. Though Eilperin doesn’t mention this, a tagged female great white (improbably named Nicole) was tracked crossing from South Africa to Australia and back – a total of 12,000 miles – in nine months.

Eilperin has unearthed a great deal of shark history and trivia, from Pliny’s description of attacks on pearl divers, to accounts of Hawaiian kings ordering gladiators to fight sharks to the death in watery arenas, to Churchill’s wartime stance: ‘The British government is entirely opposed to sharks.’ Her basic line – one shared by most shark experts – is that, where Europeans have long viewed them as terrifying, ravening beasts, those who live in much closer association with the sea, such as Pacific or Indian Ocean islanders, tend to have a more ‘nuanced’ and respectful attitude. Sharks were, and in some cases still are, worshipped as ancestors and protectors of fishermen, as well as bloodthirsty spirits that have to be propitiated, sometimes with human sacrifice. Western Europeans didn’t have much to do with sharks until the age of exploration. The English word shark isn’t even recorded until 1569, possibly stemming from the Mayan term xoc. The earliest shark attack listed in the International Shark Attack File was in 1580, when a seaman fell overboard between Portugal and India: ‘There appeared from below the surface of the sea a large monster … it rushed on the man and tore him to pieces before our very eyes. That surely was a grievous death.’

There are three​ defining events in modern American shark mythology. First, the attacks of 1916, when four people were killed in one week in five separate attacks off New Jersey, two at beach resorts and two in Matawan Creek, more than a dozen miles inland. It created mass hysteria, launched a wave of shark-hunts and gave rise to the myth of the serial man-eater – something that all the evidence tells us is wrong. The second was the sinking of the USS Indianapolis on 30 July 1945, in the final weeks of the Pacific War. The cruiser, which had delivered the uranium for the Hiroshima bomb, was sunk by a Japanese submarine between Guam and the Philippines. Of the 1200-strong crew, 300 were killed during the sinking; the survivors spent four days in the water, during which all but 317 were killed by exposure, dehydration and sharks. The third event was Jaws, which bundled up the earlier two into a slick package that spread rampant shark-phobia across the world: Peter Benchley’s novel was based on the Jersey attacks, and Quint, the Ahab-style shark hunter played with scenery-chewing vigour by Robert Shaw in the film, is a veteran of the Indianapolis disaster. Benchley, Eilperin says, did more to instil ‘intense fear and hatred of sharks than anyone else in the 20th century’. By bringing an age-old nightmare to life, he ‘gave it a credibility, a sense of concreteness, it had never had before’.

Demon Fish is good on the general phenomenon of shark attacks – or ‘shark encounters’, as marine biologists like to call them, since most of them are exploratory, defensive or accidental. The majority of recorded incidents are little more than the aquatic version of dog bites. New Smyrna beach, a popular surfing spot in Florida, is numerically the world’s number one site for shark attacks: small species like blacktip and spinner sharks snatch a surfer’s flashing hand or leg after mistaking it for a fish, usually leaving only a small flesh wound. The more serious ‘classic’ shark attack will be by one of the two big species that prey on marine mammals, the white or tiger shark; or by the bull shark, which lives close inshore and up rivers, eats everything from dolphins to small sharks and, on occasion, horses – and has ‘the highest level of testosterone of any animal on earth’. In most cases, they follow the ‘bite and spit’ pattern: the fish will take a bite out of a person, then spit it out when it realises it’s a bony human rather than a fat seal or sea lion. The research reveals how uninterested sharks are in preying on humans. Acoustic tag data shows that great whites spend a great deal of time swimming just off some of South Africa’s most popular beaches. Marine biologists on aerial spotting missions see them ‘swimming among the bathers and the surfers. We see it from the air and everyone’s blissfully unaware and quite happy.’

So the rare attacks on humans are basically cases of mistaken identity. There are simple ways of reducing the infinitesimal risks, even in waters inhabited by large sharks. Don’t swim at dawn or dusk, when many sharks feed. Don’t swim in murky water, especially near river mouths. Don’t urinate in the water, or swim if you’re bleeding. Don’t thrash around too much, or swim with a dog, or near schools of fish. Spearfishing, and to a lesser extent surfing, will definitely raise the odds of a bite. Don’t wear shark-attracting contrasting colours, particularly not the safety yellow favoured by coastguards – researchers call it ‘yum-yum yellow’. Pulling a shark’s tail is strongly discouraged. But even if you are attacked, your chances of survival are around 90 per cent. ISAF has some no-nonsense advice on what to do if the worst happens:

We advise a proactive response. Hitting a shark on the nose, ideally with an inanimate object, usually results in the shark temporarily curtailing its attack. One should try to get out of the water at this time. If this is not possible, repeat bangs to the snout may offer temporary restraint, but the result will likely become increasingly less effective. If a shark actually bites, we suggest clawing at its eyes and gills, two sensitive areas. One should not act passively if under attack – sharks respect size and power.

Yet humans go on being doggedly scared of sharks – much to the annoyance of their supporters on shore. People are sanguine about driving, even though crashes are an everyday occurrence. Yet one isolated shark hit will produce demands for shark nets or eradication programmes, or even, on one occasion in South Africa, that helium balloons should be tied to the tails of great whites so that they could be seen approaching the beach. South African conservationists tried to put the danger in perspective by pointing out that hundreds more people are killed every year in furniture-related accidents than by sharks: they did a Jaws-style advert in which the unseen creature scaring bathers out of the water was revealed to be a chair. Yet people are stubbornly irrational. As one exasperated scientific paper concluded: ‘Even though shark attacks are a minor cause of mortality for humans, this phenomenon receives an inordinate amount of media cover and interest, probably due to humans’ psychological abhorrence of being eaten alive.’ Yes, I imagine that weird hang-up has something to do with it. Because obviously sharks stoke deep evolutionary terrors that a car or a chair can’t compete with; as Steven Spielberg proved, sharks produce a supremely efficient balance of unknown fears – whatever’s happening under the water – with highly specific ones. The stats and the shark’s motivation are no consolation if your ‘encounter’ turns out like this:

The victim, Shirley Anne Durdin, was snorkelling for scallops with her husband, Barry, and a friend, Keith Coventry, out from Wiseman’s Beach, Peake Bay, South Australia. Peake Bay had always been a popular picnic spot and the beach was dotted with families, including Mrs Durdin’s four children. It was a beautiful day with clear calm water. Keith Coventry told me that he was just swimming away after comparing his scallop catch with that of Mrs Durdin, when he heard a strange sound, but definitely not as the papers reported, terrible screams … ‘I heard a sound rather like a sharp groan. Turning around I saw Shirley high above the surface. My first thought was how could she lift herself up like that, then a huge fin broke the water. There was some thrashing and the surrounding area turned dark. I instinctively swam towards Shirley, then thought: “Hey, what can I do? She’s gone.” Turning back, I saw Shirley’s husband, Barry, standing ten metres away on some submerged rocks about to enter the water. I swam to him and said: “Don’t come in, a shark has taken Shirley, she’s gone, completely gone.” Barry was shattered. “I must go to Shirley. I must help her,” he cried, but knowing it was useless, I held him back lest he meet the same terrible fate as his wife. We struggled for a minute, then turned towards the beach. The 120 metres looked like 120 kilometres. I don’t think I have ever swum so hard in my life. One of my flippers came off, but I dared not hesitate to retrieve it. The thought of that huge black shark kept me going.’ A Mr Hirschausen, watching from a nearby cliff, raced to his dinghy at the water’s edge. Within minutes, he and a friend had launched his boat and headed towards where he had last seen the woman. Her head and top torso were floating in a pool of blood, but before the rescuers could reach the remains, a great conical nose broke the surface and snatched them down, leaving nothing but empty blood-stained water. A huge search was organised, but only one blue flipper was ever found.

This excerpt comes from a rather brilliant out-of-print book called Great Shark Stories, by Valerie and Ron Taylor, a couple of shark-bothering divers: my only real complaint about Demon Fish is not exactly a grown-up one – there aren’t enough blood-curdling eyewitness accounts of shark attacks.

But Eilperin has her mind on higher things. As an environmental journalist, she mostly sees sharks as the canary in the coalmine. They reveal a great deal about the ocean: ‘how it functions, and why it is now in peril’. A pristine marine environment, certainly in the tropics, will be swarming with sharks; they help to keep mid-level predators in check, and the whole ecosystem healthy. In the untouched Shangri-la-like Kingman Reef in the Line Islands in the central Pacific, sharks make up 75 per cent of the fish biomass. Elsewhere, as long-lived predators producing a limited number of offspring, sharks are very vulnerable to collapse due to overfishing. Evolutionary strategies that have kept them dominant for millions of years leave them helpless; stocks tend to plummet within a few years of being targeted. Meanwhile, factory ships restlessly search for new species to exploit, and the shark fin trade is growing fast: shark fin soup, regarded as a bourgeois extravagance under Mao, is now exploding in popularity across China. And since it’s a status symbol, scarcity drives up prices: the shark fin apparently adds nothing to the taste, only tasteless noodle-like cartilage and an aura of value. It’s a sad, familiar story, and as ever the forces ranged against the juggernaut are pathetically inadequate: a few loosely worded protections, and some unwieldy, disputatious international bodies. Sharks are facing an extinction crisis. If things go on like this, they will be mostly wiped out or driven into a few well-protected margins, becoming little more than a folk memory.