Effectiveness Against White Sharks of the Rpela Personal Shark Deterrent Device Designed for Surfers

Abstract

Many shark bites to humans, including fatalities, have involved surfers. Various personal shark deterrents are commercially available to surfers, including Rpela v2, which is a battery-powered device fitted to a surfboard. It produces an electric field around the surfer aimed at deterring sharks from approaching or biting by disrupting their electro-reception organs. The device was tested on white sharks (Carcharodon carcharias) at Salisbury Island, Western Australia. In total, 46 trials were done with the Rpela v2 either active or not active to determine the device’s effect on sharks’ response to a floating board with fish bait attached (to tempt a bite). When active, Rpela v2 significantly reduced the probability of a bite (0.75 to 0.25, a 66% reduction) and interaction (i.e. bite or touch) (0.80 to 0.50, a 38% reduction) occurring compared with when it was inactive. The number of passes taken by a shark also reduced and the mean distance between the shark and the bait increased when Rpela v2 was active. It is noted that Rpela v2 did not completely remove the risk of shark bite, but the magnitude of the reduction in risk is of a level that surfers are likely to consider meaningful and it could be expected that Rpela v2 would provide more time for surfers to leave the water (i.e. as inferred from the number of passes) when a potentially dangerous shark is present. Implications for the role of personal deterrents in strategic management of the risk of shark bite are also discussed.