Surfers may soon find a safer way to enjoy the waves, thanks to groundbreaking research by Professor Nathan Hart, head of Macquarie University‘s Neurobiology Lab, Dr. Laura Ryan, and their dedicated team.
In their recent paper published in Current Biology, the researchers present findings that could pave the way for innovative, non-invasive shark deterrent technologies aimed at protecting human lives.
The researchers had previously determined that great white sharks heavily rely on their eyesight to identify prey, often lunging upward to catch potential meals like seals in their mouths.
In related research, scientists have discovered that great whites are likely entirely colorblind and possess limited visual clarity, which is offset by their strong capability to detect silhouettes. However, due to their poor vision, these sharks struggle to differentiate between the shapes of a surfboard or a person in the water and that of a seal, which makes them a threat to humans.
Researchers have ingeniously drawn inspiration from juvenile plainfin midshipman fish, which possess remarkable photospores on their undersides that emit light and obscure their silhouettes. To combat the threat posed by sharks, they developed a promising method to disguise silhouettes on the water’s surface using strategic lighting, ensuring that sharks would be unable to recognize decoys as potential prey.
Over a span of six years, Dr. Ryan embarked on multiple expeditions to the notorious great white shark hotspot of Mossel Bay in South Africa to test this innovative counterillumination strategy. During these investigations, the team towed seal-shaped foam decoys measuring 1.2 meters along a 20-meter line behind a boat, effectively attracting sharks.
Then, they applied LED lights in various arrangements to disrupt the silhouette of the decoys. They discovered that lights arranged in stripes along the bodies of the seal decoys, placed perpendicular to their movement, were an effective deterrent, enhancing safety in the shark-infested waters.
“It’s sort of like an invisibility cloak but with the exception that we are splitting the object, the visual silhouette, into smaller bits,” says Professor Hart. “It’s a complex interaction with the shark’s behavior. The lights have to be a certain pattern, a certain brightness.”
Journal reference:
- Laura A. Ryan, Enrico Gennari, David J. Slip, Shaun P. Collin, Victor M. Peddemors, Charlie Huveneers, Lucille Chapuis, Jan M. Hemmi, Nathan S. Hart. Counterillumination reduces bites by Great White sharks. Current Biology, 2024; DOI: 10.1016/j.cub.2024.10.042
