The other day, during the world surfing tour, social media exploded when three-time world champion surfer had an up close encounter with a great white shark in Jeffreys Bay South Africa.

Luckily, he got away unscathed, however the reputation of these top predators certainly has not. Millions of viewers watched the encounter on live television and the media has predictably latched onto the story that is bound to generate clicks.

But all this does is fuel the fire of unfounded fear that people have of sharks. This has gotten completely out of hand - with perhaps the most poignant example being these people unbelievably making personal shark cages in the United States.

Ever since the movie Jaws sensationalised shark attacks, vigilante-style culling that has been wrongly justified by fear - rather than any science - has made these apex predators' population drop and is having a disastrous impact on biodiversity in the ocean.

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Local shark scientist Riley Elliot explains that "Overfishing, by-catch and the shark fin industry combine to kill 70-90 million sharks a year. Sharks need our help not only to protect them - but also our fisheries and ocean ecosystem as a whole. Sharks, as apex predators, keep a balance in the ocean created over millions of years of evolution."

While the media have inflated the story, calling it an 'attack' and giving the surfers in the water immediate hero status, the reality is that the shark was simply curious. It was a very large animal and if it had wanted to eat one of them, it would have - simple as that.

The important thing to realise here is that it didn't.

As someone who knows sharks intimately, I have a theory about how to reduce attacks on humans: make sure there is enough food for them around and don't have them associate humans with food.

I learned to surf in Dunedin, which is well known as a breeding ground for great white sharks. In the 60s there were four fatal shark attacks in the Otago area. Out of a total of 12 ever in New Zealand's history, this is quite a lot. This is also before wetsuits, which allow us to spend far more time in the water, were available.

These days, there are hundreds of surfers spending hours frolicking around in soupy river mouths and looking like the marine mammals that the sharks eat, but no attacks. Why?

Up until 1946 (when 6,187 seals were killed in Otago and Southland for fear they were impacting the fisheries), there was mass killing of seals for their oil and pelts. I believe that in the 1960s, there was not enough food around for the great whites because the seal population had been depleted.

Today, seals are abundant in Otago and share the water with the surfers. The great whites are still there, but they don't attack. I think they know the difference between a seal and a human and choose the delicious fatty marine mammals rather than stringy surfers.

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I have been told that in South Africa and Australia - where attacks are far more common - the great whites are usually eating tuna. No surprise then, that they go for humans, because the tuna stocks have been thoroughly decimated through the advent of GPS, air support and big industry pillaging the fish.

But back in New Zealand, with our ever-increasing curiosity and thrill-seeking tourism efforts, this apparent harmony between man and shark could be threatened.

Shark-cage diving has become a big thing in South Africa and now also, in Stewart Island and I think this is stupid. This is getting called 'eco-tourism' because it involves looking at the animals rather that killing them and seems like a good idea ecologically at first. But we are literally baiting them in, so that punters can take a photo from behind steel bars and associating humans with food.

Will this disrupt the balance between shark and man?

I the meantime, I for one will continue to enter the ocean as the odds are still remote enough for me to take a calculated risk - as any surfer or spearfisher knows - and enjoy what our epic coastlines have to offer.