Magazine article Geographical

Swimming with Big Fish

Magazine article Geographical

Swimming with Big Fish

Article excerpt

It is 11.45am on the edge of Ningaloo Reef. The spotter aircraft flying 300 metres overhead has located the giant tadpole shape of a whale shark. The pilot radios the shark's position to the skipper. Seconds later the boat throttles up in pursuit. For the 14 people in the boat -- wearing wetsuits, masks, snorkels and fins -- the time has come. Within minutes, the boat is ahead of the shark and the lead swimmer jumps in, raising his hand above his head to show he is in position and can see the whale shark. On board, the dive controller calls "Go, go, go". It is just like a parachute jump. In two rows of four the snorkellers jump into the sea and wait expectantly, treading water. Seconds later, a huge slit of a mouth -- over a metre across -- emerges from the plankton-rich waters, and behind it the body of an eight-metre whale shark. Adrenaline drives the group forward, and from a standing start they are swimming at top speed alongside the world's biggest fish.

Ningaloo Reef lies 1,100 kilometres north of Perth in Western Australia alongside a promontory called the North West Cape. Protected within the Ningaloo Marine Park, it is the world's largest flinging reef and a coral paradise for scuba divers and snorkellers rivalling the country's more famous Great Barrier Reef. The 260-kilometres-long reef comes as close as a few hundred metres from the shore with superb reef formations accessible right off the beach.

The spectacular reef is not the only draw to Ningaloo. Visitors come here to fish for big game (marlin or sailfish) and to see dolphins, dugong, humpback whales and turtles nesting on the nearby beaches. Yet its star attraction is the whale shark (Rhincodon typus) -- the world's largest fish -- which cruises outside the reef between March and late May. There are few places in the world where these fish visit with such predictability.

Data on the biology and ecology of whale sharks are surprisingly sparse; the World Conservation Union (IUCN) classifies its conservation status as "data-deficient". And it was only in July 1995, when an 11-metre female was harpooned off Taiwan, that the whale shark was confirmed to bear live young (ovo-viviparous) rather than laying eggs (oviparous).

Little is known about Ningaloo's whale sharks. No one knows where they go to when they leave the reef, how big the population is, how old the individuals are, and precisely why their numbers fluctuate from year to year. However, they are probably attracted to Ningaloo by the abundance of food. Blooms of phytoplankton (plant plankton), and the synchronised spawning of about 100 or so coral species, provide food for zooplankton (animal plankton) which, in turn, are sustenance for schools of bait fish. Whale sharks feed on both the zooplankton and fish.

The size and non-aggressive nature of the whale shark is its major appeal. The biggest are reputedly 18 metres long, although few in Australian waters reach more than 10 metres in length. Their speckled body patterns are beautiful, their bulk awe-inspiring, and their good nature remarkable. Unlike some sharks, which are voracious predators of fish, the whale shark feeds by swimming around with its mouth open, filtering small plankton from the surrounding water.

"The whale shark is as big as a bus, but graceful," explains Kristina Morawetz, a regular visitor. "Once you've seen one, you want to see more." Former diving instructor Gordon Jio from Sante Fe in New Mexico is equally enthusiastic. He has logged hundreds of dives and has swum with some of the world's biggest whales. Now he wants to see the world's largest fish. "I told my wife before I set off for Australia that I can die a happy man once I've seen a whale shark," he says.

Commercial boats have been taking people out to see Ningaloo's whale sharks since 1989, and today there are 14 charter boat operators offering full or half day excursions. The industry, based mainly in the town of Exmouth, generated an estimated A $10 million (3. …

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