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How to avoid a shark attack

It may be small comfort when 300 serrated teeth tear into your flesh, turning the surf red, but great white sharks don’t have it in for you.

A new study has shown that if you are unlucky enough to be attacked by one, the chances are it is simply a very unfortunate case of mistaken identity.

Researchers approached the question of great white shark attacks by trying to look at the problem as a shark would.

Confirming what marine biologists have long suspected, their research has shown that if you are lurking on the ocean floor and viewing the world above as a shark does, there is very little difference between a seal swimming and a human swimming or paddling on a surfboard.

Shark attacks are extremely rare. Accurate figures are hard to come by, but last year there were 10 confirmed human deaths caused by sharks.

Writing in the Journal of the Royal Society Interface, the authors of the latest study argue that a handful of attacks can have outsized effects – devastating local tourism and leading to reprisals on sharks themselves. Understanding the cause of attacks is therefore important.

A long-standing theory, which would also explain why surfers appear to be disproportionately affected, is that human limbs paddling a surfboard look like the flippers of a seal. Rather than targeting surfers, the sharks are simply trying to catch their standard prey.

The scientists’ work involved testing this idea by filming seals and humans from underwater and processing the images to approximate how they would look to sharks, which are colourblind and less able to see detail than a human. Finally, they used image analysis to compare the shape and motion of the two.

They found that, when seen with ‘‘shark vision’’, the swimmer and the surfer were such a good approximation to a seal, even in clear water, that they were statistically indistinguishable.

‘‘While it seems unlikely that every bite on a human by white sharks is a result of mistaken identity,’’ the scientists write, ‘‘our results suggest that in circumstances where surface objects, like surfers, are targeted by white sharks from below, it is very possible.’’

The ‘‘mistaken identity’’ theory of shark attacks would also explain why sharks often give up the attack after the first bite, which is often more of an exploratory nibble than a full-force chomp. ‘‘Differences in electromagnetic [and] gustatory cues cause white sharks to reduce the intensity of their bite’’, the researchers write.

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2021-10-28T07:00:00.0000000Z

2021-10-28T07:00:00.0000000Z

https://fairfaxmedia.pressreader.com/article/281934546159919

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