Biology

Computer models back up theory that sharks mistake surfers for seals

Computer models back up theory...
Does this look like a seal to you? Juvenile great white sharks likely think it does
Does this look like a seal to you? Juvenile great white sharks likely think it does
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Does this look like a seal to you? Juvenile great white sharks likely think it does
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Does this look like a seal to you? Juvenile great white sharks likely think it does

If you've seen even a single shark documentary, then you've probably heard that the majority of attacks on humans are likely due to sharks mistaking people for seals. Scientists now say they've confirmed that theory, using computer models.

A large percentage of shark attacks involve great white sharks attacking surfers as they sit on or paddle their boards. In the past, studies have shown that when viewed from below, surfers on boards have a silhouette similar to that of pinnipeds (seals and sea lions) – these animals are among the great white's natural prey.

Led by post-doctoral researcher Dr. Laura Ryan, scientists at Australia's Macquarie University recently set out to explore this theory further.

Doing so involved using both stationary and travelling upward-facing cameras to shoot underwater video of subjects such as rectangular floats; pinnipeds swimming; humans swimming different strokes; and humans paddling on surfboards of various sizes. The footage was shot in a large tank at Sydney's Taronga Zoo. For the travelling shots, a GoPro was mounted on an underwater scooter that was moving at "a typical cruising speed for predatory sharks."

The footage was subsequently analyzed utilizing computer models based on existing shark neuroscience data, which simulated the manner in which a juvenile great white shark would process the shapes and movements of various objects. Juveniles are involved in a disproportionately large number of attacks, likely due to the fact that their vision is poorer than that of their adult counterparts.

The analysis reportedly confirmed that young great whites are indeed prone to mistaking humans on surfboards for pinnipeds, as the sharks likely perceive the two as looking very similar – this is particularly true of people on short boards. Changing the colors of the boards probably wouldn't help, as it is believed that sharks are mostly color blind. The scientists are looking into other preventative measures, however, such as adding high-intensity LEDs to the underside of boards, to break up their silhouette.

"Understanding why shark bites occur can help us find ways to prevent them, while keeping both humans and sharks safer," says Ryan.

The research is described in a paper that was recently published in the Journal of The Royal Society Interface.

Source: Macquarie University

8 comments
8 comments
Mick Perger
I`ve been a surfer for the best part of 40 years. Most surfers realised this more than 50 years ago. Sharks are known to attack from underneath, and most will, after one bite will realise their mistake spit you out and swim away. Mostly sick or starving sharks will continue their attack because they have no choice. I myself had a friend die from a shark attack. Unfortunately, he was bitten behind the knee, severing the main artery, and being in a remote area bleed out before help could arrive.
James Floyd
Pssssssst....Great white sharks are not computers. Apples to oranges. A computer result will only output what a human input wants. Also not great for weather results and climate results as well.
Arttai
Surfers should carry a marker of some sort that can help sharks distinguish them from seals.
martinwinlow
Why, then, are so many wet suits just (very seal-like) plain black and not garishly coloured? Or are sharks a/ myopic, b/ colour-blind and/or c/ just not fashion-concious?
kamikrazee
Didn't Richard Dreyfuss explain all this in the first Jaws film?

and still we swim.
noteugene
Anyone with an ounce of common sense could see that odds of being bitten would decrease if both the board and suit were outfitted with bright flashing led lights. Ankle bracelets if suits are not being worn. Don't need a study for that. I wouldn't risk life or limb for a few minutes of an adrenaline rush. Don't see why some of these manufactures in various fields can't be helping our thrill seeker friends out. Or at least somebody go into business making flashing ankle bracelets. Cheap enough to test out.
Chris D
Flashing lights is probably a bad idea,
as it would mimic the flashing scales of bait-fish reflecting sunlight.
May prove to do the opposite of whats intended.

Surfers with the sun above them are back-lit.
As such the colors of the board and suit would be unimportant,
as they would be blacked out in a shadow (think dark side of moon).
Nelson Hyde Chick
This will be a non problem as on account of overfishing, plastic pollution and climate change making the oceans acidic there will be no sharks.