Sharks are a contentious topic in Western Australia, with the issue of how to curb attacks on humans dividing communities and the government. Last year, a government-sponsored cull of sharks – initiated in response to a spate of attacks in the state's waters – was shown to fail and was then blocked by the state's environmental regulator, but that hasn’t made the problem disappear. A new study, however, has found that an already commercially available humane deterrent prevents more than 90% of shark encounters.
The study, conducted by the University of Western Australia’s Ocean Institute, measured the effectiveness of different types of deterrent in preventing sharks from approaching a baited test rig. These included strobe lights, orca vocalizations, bubble barriers, and an electric field. While the others showed mixed success, the electric device, already commercial available as the Shark Shield, stopped the vast majority of sharks from approaching.
“We hope this will ultimately lead to the development of new shark deterrent technologies in the future,” said Professor Shaun Collin, who was involved with the study, in a press release. The team tested the devices on a baited rig, and compared the results to a control rig where no device was in use. They conducted the tests both off the coast of Western Australia with reef sharks, and in South African waters with great whites.
They found that the strobe light can be effective against strongly nocturnal sharks or species that dwell at depth, but were not as effective against diurnal species (those active during the day). The orca noises were not shown to have much of an impact, and although the bubbles were found to drive the sharks away initially, they quickly became used to them. However, this could indicate that bubbles may be useful as a one-off deterrent for scuba divers.
The electrical device, however, showed significantly more promise. It works by interfering with the electroreception system that sharks use to detect both prey and predators. The researchers tested another commercially available electronic device but it was not found to be nearly as effective as the Shark Shield. Collin hopes that the devices can somehow be adapted to create “invisible” shark barriers. The study was funded by the Western Australian government as part of their shark hazard mitigation policy.
Watch the video below of the researchers talking through their results: