AFP, Released Wednesday, October 27, 2021 at 2:11 p.m.
According to a study conducted Wednesday, scientists have concluded that sharks, which prey on surfers or bathers, may have poor eyesight and may mistakenly think that their regular prey is sea lions.
The authors of the article write in the Royal Society’s magazine Interface, “In the view of a white shark, neither movement nor shape allows for a clear visual distinction between finnipets and humans.” They conclude that their work “supports the theory of misidentification to explain certain bites.”
“This is the first study to test this theory from the point of view of the white shark,” its lead author, Laura Ryan, a researcher in the Department of Biological Sciences at the Australian University of Macquarie, told AFP.
According to the University of Florida Department of Fine Arts, shark attacks are rare (less than sixty worldwide by 2020). But according to their study, they maintain a climate of “disproportionate” fear associated with ignorance of animal motivations, especially when the attack is not triggered. Sometimes the resulting poaching campaigns can be harmful to other creatures as well.
Often blamed, white sharks, tigers and bulldogs, often attack surfers.
If the white shark is known to detect sounds and smells at great distances, it is thought that when viewed up close it will mainly rely on its sight and target its prey.
– insensitive to color –
However, the shark’s visual structure is almost insensitive to color and its ability to distinguish the details of a shape is very poor. Its resolving power, which is six times less than that of humans, is even lower in young white sharks, which pose a greater risk of dangerous bites to surfers, the study said.
To test the theory of misidentification, the scientist explains that Macquarie’s team “created videos taken from a shark’s view and processed them with a program that reflected the shark’s visual structure” and specifically the ability to differentiate a shape and its motion.
To this end, they recorded pictures and videos of a sea lion and a fur seal from a bed, which was tasty for a shark, near the surface, a few meters above sea level, above a shark. They then paddle their signals with their hands by swimmers and surfers, and paddle on three main types of surfboards (longboard, shortboard and hybrid) with or without kicks.
The study found that in the eyes of a young white shark, the swimmer’s movement signals, such as paddling on his board, are almost indistinguishable from a pinnipet.
A portiori in seawater, where the view of the basin used for testing is less.
In terms of shape, the knit with the folded paddles looks more like a swimmer or surfer on his shortboard than a knit with the elongated paddles. “Long boards look less like sea lions,” says M Ryan, noting that “there are biting incidents on long boards”.
“Researchers will now try to determine whether a change in the visual signals of potential prey would be an effective technique for protection against white sharks,” the scientist continues.
With the compulsion of solutions that “not only prevent shark bites, but also do not pose a danger to other marine organisms.”