Swimming with Whale Sharks / Telegraph Magazine

“Preparez-vous! Preparez-vous!” our captain shouts. Then “Allez! Allez! A droite!”.

Flippers on, masks down and snorkels up, we slide rapidly into the water from the rear of the boat. For a few seconds we can see nothing but bubbles. Then they clear, and we spot a huge whale shark swimming straight towards us – flat-headed with a yard-wide mouth.

We paddle back to avoid him, but the enormous creature takes no notice. He glides past us – all 18 sleek feet of him. We turn and follow.

The next minute or two are sublime, thrilling, unforgettable. The whale shark swims serenely on through brilliant clear blue water lanced by refracted sun beams. We are so close we can see his small black eyes and the holes just behind them, his layered gills and the sharp, parallel ridges running down his back. We admire the hundreds of white circles that are scattered randomly across his head but run in geometric lines down the length of his great blue-grey body.

He proceeds like royalty with a retinue. Tiny yellow-and-black-striped pilot fish swim just ahead of him, riding his bow wave. Skinny white sucker fish tuck themselves in behind his pectoral fins, some literally attaching themselves to his skin like velcro. Other fish – cobia and jacks – follow in his wake, hoping he will lead them to food.

We are transfixed, awestruck, oblivious to the small, purple-ringed jellyfish brushing past us. Then, with a sideways flick of its powerful tail, the whale shark begins to dive. Deeper and deeper he goes until all we can see are the white sucker fish just above him. Eventually they too disappear into the dark blue depths.

Our pursuit is over. We swim – elated - back to our boat where Arthur Guillemain-d’Echon, the French owner of a whale- and whale shark-watching business called Les Baleines Rand’eau, is already scanning the surrounding waters for the tell-tale signs of other whale sharks.

As he does so we dry off in the hot sun. Far to the south, across the rippled sea, we can make out the mountainous outline of mainland Madagascar. To the east, much nearer, lies the large offshore island of Nosy Be from whence we have come. A host of other small, hilly, forested islets dot the water. So do boutres (dhows) with great white sails shaped like giant shark fins, and the small wooden pirogues - with their crude outriggers and colourful home-made sails - of umpteen fishermen.

Then we speed off again. Our Malagasy spotter has seen in the distance a commotion of white terns swooping and diving into the water. As we approach, we see hundreds of tuna leaping in pursuit of bait fish.

Guillemain d’Echon slows the boat and scans the boiling water. He soon spots a great grey form just below the surface. He manoeuvres our boat into its path. “Preparez-vous!” he cries, and we slide back in to the warm waters of the Indian Ocean for our sixth exhilarating encounter with a whale shark that morning – tourists, yes, but also active participants in a concerted effort to save those extraordinary creatures from extinction.

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Whale sharks, named for their size, caught the popular imagination with their starring role in the BBC’s ‘Blue Planet’ series. They are the biggest fish in the world, the biggest that have ever existed. They are bigger than most whales, bigger even than the long-extinct megalodon which preyed on whales. A mature adult can easily weigh 20 tons and measure 40 feet - the length of a bus. The longest ever caught allegedly measured 65 feet, and the heaviest weighed 42 tons.

Whale sharks are also an endangered species whose numbers have halved since the 1980s – a victim of overfishing, the indiscriminate use of gill nets, collisions with boats and the Chinese taste for shark fin soup.Their presence in the relatively shallow, nutrient-rich waters off Nosy Be was first recorded by a couple of western scientists in 2007, but political unrest deterred further research until a young Belgian conservation biologist named Stella Diamant, a graduate from Warwick University, visited Nosy Be in 2014. She found there were more whale sharks there than anybody realised. “They were so big and beautiful. I was blown away that these things still existed,” she said.

Diamant, now 29, contacted Simon Pierce, the New Zealand-born head of the Marine Megafauna Foundation and a leading authority on whale sharks, who agreed to oversee a research project.

In 2016 Diamant identified 85 whale sharks during the three months from mid-September that they spend feeding on the shoals of tiny fish off Nosy Be (each whale shark has its own unique set of markings). In 2017 she identified a further 115. By the end of 2018, with the help of Les Baleines Rand’Eau, she had found more than 280.

“I was highly impressed. It meant this was a pretty significant hot spot,” Pierce told me as we headed north from Nosy Be on a catamaran three days after our adventure with Guillemain d’Echon. There were scarcely 30 such locations left in the world, he said, and even fewer where adventurous tourists could swim with the whale sharks.

Over the next two days Pierce, Diamant and I sailed to the remote archipelago of Mitsio, 30 miles away, to see whether there were more whale sharks feeding there.

It was a memorable voyage. We saw flying fish and sail fish, dolphins, a leopard shark, a manta ray and a pair of Omura’s whales – a species so rare that they were only officially recognised in 2003. We watched two humpback whales breaching, spouting and exuberantly slapping the water with their tails. Our crew caught barracuda and Spanish mackerel which we ate grilled, and as ceviche, barely an hour after they were hauled from the water.

We visited a thatched-hut fishing village that lacked mains electricity or running water, and was accessible only by boat. We stopped on a tropical island with beaches of pristine white sand washed by aquamarine waters. On another island we admired a vast cliff of vertical basalt columns known as the ‘Organ Pipes’ that thoroughly eclipsed Northern Ireland’s Giant’s Causeway.

Both evenings we witnessed flaming red sunsets, and a full moon rising above the tranquil sea like a powerful headlight.

We saw no whale sharks, but I learned a lot about those remarkable creatures from Pierce and Diamant. Or, more accurately, I learned how little is known about them.

Almost all the whale sharks who feed off Nosy Be, and in the world’s other coastal hot spots, for two or three months each year are juvenile males under the age of 30. Where they go for the rest of the year, and where female and adult male whale sharks dwell, is a mystery, though the best bet is that they live far offshore in the Pacific and Indian oceans. “They’re the biggest fish in the sea, but the oceans are even bigger,” says Diamant, who is tagging a few in an effort to find out more.

We know they dive deeper than any other fish, and that one tagged whale shark reached a depth of 6,324 feet, but nobody knows why. They feed on plankton and tiny fish, which they catch by gulping and filtering vast amounts of water through their mouths and gills, but there is no food at such depths.

We do not know how they reproduce, though males have two ‘claspers’ or penises. No whales sharks have ever been seen mating or giving birth. Just one pregnant female has ever been caught – off Taiwan in 1995. She had no fewer than 304 pups inside her, twice as many as have been found in any other species of shark. Some were still in an embryonic state, others hatched and swimming freely in her uterus.

One of the only places where adult whale sharks are found is the Galapagos Islands, and until recently scientists believed that was where females went to spawn – a claim repeated on ‘Blue Planet’. But earlier this year Pierce and a team of researchers performed ultra-sound tests on some apparently pregnant whale sharks there, and discovered they were not pregnant at all.

We do not know what age whale sharks live to – estimates vary from 70 to 130 years. Nor do we know how many are left in the oceans. “Put a gun to my head, and I’d say tens rather than hundreds of thousands,” said Pierce. One reason for this lack of knowledge is that dead whale sharks do not wash up on beaches, like whales, but sink without trace because they have no blubber.

Amongst the very few things we think we do know is that they grow skin that is nearly ten inches thick, have only tiny, vestigial teeth and do not communicate with each other. Despite their latent power and strength, they also happen to be utterly gentle - unlike other members of the shark family. And that, inevitably, makes them a magnet for adventurous tourists.

“They are mesmerising,” says Diamant, who says that each has its own personality and has given all of Nosy Be’s whale sharks names. “Some are shy, some curious and some not bothered.”

Pierce calls them ‘Labradors of the sea’. “There are no other animals that size you can interact with in complete safety and with no training,” he says. “Not only are they placid but they’re completely adorable. Everyone comes away as ambassadors for whale sharks. It changes people’s lives.”

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Nosy Be has long attracted European tourists. They come for its climate, beaches and coral reefs, its diving, whale-watching and deep sea fishing. They come to see the lemurs, boa constrictors and amazing geckos and chameleons in the densely forested Lokobe national park (I stared straight at a six-inch leaf-tailed gecko on a tree trunk without seeing it, so perfect was its camouflage).

They come also for the relaxed co-habition with the handsome, friendly Malagasy people, and for the lush vegetation. Everything grows on the so-called ‘Perfumed Isle’: pineapples, guavas, mangos, limes, lychees, cocoa, jack fruit, vanilla, bananas, chilli peppers, orchids and the exotic ylang ylang tree.

Now, increasingly, tourists are also coming to swim with Nosy Be’s newly-discovered whale sharks – the fish the Malagasy people call ‘marokintana’ (‘many stars’) after the markings on their backs.

Three years ago just a couple of operators offered tourists that opportunity. Today about 15 do, charging a modest 50 euros for a half-day excursion that includes a traditional lunch in a beachside hut and, at the end, a chance to snorkel above huge green turtles grazing like cows on seabed weed. Several international airlines have recently launched direct flights to Nosy Be that avoid Antananarivo, Madagascar’s dodgy capital.

Normally such an influx would fill conservationists with alarm. Too often tourism destroys the very wonders that it feeds off. But happily Pierce and Diamant insist that precisely the opposite is true in the case of Nosy Be’s whale sharks.

Counter-intuitively, they argue that well-managed tourism offers the best hope of protecting Nosy Be’s rare and priceless aggregation of those giant fish. They hope it will persuade local people that they are worth much more alive than dead by generating income for hotels, restaurants, boat owners and guides in one of the world’s poorest countries.

“Tourism creates an economic incentive for conservation and management. It is really useful for whale shark conservation. It’s a $100 million industry around the world, and provides a clear argument for protecting the species,” Pierce contends.

“Tourism is only a threat if it gets out of control,” says Diamant, who works hard to persuade thevarious operators to adopt a strict code of conduct that limits the number of boats and swimmers that can approach a single whale shark, forbids the swimmers from touching them or the boats from venturing too close, and bans all flash photography.

They say the biggest and most immediate threat to the whale sharks actually comes from a secretive $2.7 billion deal that Madagascar’s president, Hery Rajaonarimampianina, agreed with Beijing lastSeptember which will permit 330 Chinese vessels to fish in Madagascan waters over the next decade.

That could destroy the fish stocks on which the whale sharks feed, and see them entangled in nets or caught by propellers as they migrate to or from Nosy Be. Already as many as 40 per cent of Nosy Be’s whale sharks, and 70 per cent of the wider population, bear propeller scars – some quite horrific.

In a country with a scarcely functional government and a wretched record of conservation, additional threats come from proposals to drill for oil and open a rare earth mine in the vicinity. It is a fair bet that none of the profits from those enterprises would benefit the local communities.

As with so many other endangered species, Pierce says, the race is now on to save the magnificent whale sharks of Nosy Be, and of the wider world.

“Whale sharks have never been in a worse state,” he warns. “They’re really at a tipping point. They could go into extinction, and within my lifetime we could lose the biggest fish that’s ever lived. But stop people killing them, create pride in their presence, and we think they could bounce back.”