While great white attacks are rare, surfers are particularly vulnerable as sharks can mistake them for seals.
A breakthrough study from Macquarie University in Sydney has identified a promising method to prevent great white sharks from confusing surfers for prey.
Lighting up the decoy
According to ExplorersWeb, in a series of experiments, researcher Laura Ryan and her team observed over 500 hours of great white shark behaviour.
They did this using decoys shaped like seals and towed them around Mossel Bay in the Western Cape.
Some of the decoys were equipped with various lighting patterns. The patterns were either in the form of horizontal or vertical strip lights, or strobe lights with varying levels of brightness.
These ‘lit up’ decoys were then towed and tested against unlit control decoys to gauge the sharks responses.
“We have taken the approach of understanding these animals’ sensory systems and how they see the world, [with] their behavior,” Ryan said.
The findings, which were published this week in Current Biology, reveal that sharks showed the highest interest in unlit decoys. Strobe lights reduced shark interest somewhat, while vertical strip lighting was even more effective in deterring the predators.
Breaking the silhouette for great whites
The most successful deterrent, however, was horizontal lighting at maximum brightness. With this setup, the sharks showed zero interest in the decoys. Ryan concluded that the bright horizontal lighting effectively broke up the decoy’s silhouette, making it less recognisable as potential prey.
“The most critical thing was that the brightness on the decoy had to be brighter than or equal to the background light,” Ryan noted.
“As long as the lighting stopped the silhouette from looking black, it seemed to work.”
The study offers real hope for increased safety in the surf, as LEDs could soon be adapted for surfboards and wetsuits to prevent shark attacks.
“We are now moving from research into providing protection for swimmers and surfers,” Ryan added.
Would you try a counter-illuminated wetsuit when they are available?
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