SYDNEY (XINHUA) – Light-based camouflage can prevent attacks by great white sharks on surfers, an Australian study has found.
In the new study, researchers from Macquarie University in Sydney fitted LED lights on seal decoys and towed them behind a boat in South Africa’s Mossel Bay, a renowned hot spot for great whites.
They found that sharks were significantly more likely to interact with seal decoys that did not have LED lights fitted and that brighter lights were more effective at deterring sharks.
The co-authors of the research, Laura Ryan and Nathan Hart, said that great white sharks have poor vision and rely on detecting dark objects silhouetted against sunlight from above.
The LED lights mimicked a natural ocean camouflage strategy used by several marine species and interrupted the silhouette of the seal decoys, making sharks not see them as food.
“It’s like an invisibility cloak but with the exception that we are splitting the object, the visual silhouette, into smaller bits. It’s a complex interaction with the shark’s behaviour.
The lights have to be a certain pattern, a certain brightness,” Hart said.
Covering the whole underside of the decoy with lights was found to be effective at deterring sharks but was not energy efficient. The team found the ideal approach was placing light strips across the decoy perpendicular to the direction they were being towed through the water.
Ryan said that the researchers were now working on embedding LEDs into the bottom of a surfboard and looking into whether the lights will still deter a great white when an object is stationary, like when a surfer is waiting for a wave.
She said that the team has also started testing the light system with other species of sharks.
