While shark attacks on humans are very rare, each one brings to the surface their share of anguish and fear. A scientific study published this Wednesday makes it possible to understand why surfers can become targets.
"From the point of view of a white shark, neither the movement nor the form allow an unequivocal visual distinction between pinnipeds (seals, sea lions ...) and humans", thus described the researchers of the University of Macquarie (Australia), whose work has been published in a journal of the Royal Society. They therefore support the thesis "of the misidentification to explain certain bites".
Scientists started from the observation that white sharks, tigers and bulldogs, the main culprits of the attacks (and which in fact mostly affect surfers), certainly have the ability to detect smells and sounds over great distances, but mainly use their sight. to pounce on their prey, once they are in close proximity to it.
THE SHARK SEES VERY BAD
This is a problem, since the shark is almost insensitive to color and sees very little detail in a shape. Its vision resolution, six times lower than that of humans, is even worse in young white shark specimens, which pose the greatest bite risk to surfers.
The scientists therefore developed a system to mimic the shark's visual system and used it to play back videos they had taken at the bottom of a pool. They first filmed images of a fur seal and a sea lion that would pass on the surface of the water, a few meters above the predator, then compared them with those of swimmers and surfers, doing the same route. They made passages by paddling only with the arms, then with kicks. Three types of surfboard were used: shortboard, longboard and hybrid.
SEA FEAR AND SURFER, SAME SIGNALS
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It then became apparent that the signals seen by the young shark are almost indistinguishable from a pinniped, swimmer or surfer paddling. The researchers even specified that the differentiation must be even more complicated in seawater compared to the basin used for the experiment, which offered better visibility.
The study also found that the shape of a sea lion or seal with folded fins looked more like a swimmer or surfer on a small board than one of those prey with outstretched fins. The researchers therefore indicated that they would now try to find out whether a "change in the visual signals of potential prey would be an effective technique for protection against white sharks."
Until then, it is better for everyone to continue to avoid swimming or surfing in risk areas, especially when the elements affect visibility from the bottom of the water (darkness, cloudy water, etc. ). It is also good to remember that shark attacks are still very rare across the globe (no more than 60 in 2020).
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