Why shark deterrents are a great white ‘nope’
Some costly shark repellents do not stop the marine predators approaching swimmers or even protect their whole bodies, research has revealed, and experts warn they could prove more dangerous than using no technology at all.
New independent tests, conducted by researchers from three Australian universities, labelled Electronic Shark Defense System devices "unreliable" and ineffective against sharks despite commanding more than $700, and found they left large parts of swimmers' bodies completely exposed to attacks.
The news comes after a prolific run of shark attacks in Australia, with more than 27 incidents in 2018, including the death of a man in the Whitsundays, and another five attacks so far this year.
Shark experts said the activity proved Australia needed to invest more in developing and testing shark-repelling technology.
The latest research, published in the journal PLOS One, tested the Electronic Shark Defense System (ESDS) device in South African waters.
The device, available at dive shops in Australia, is a small, battery-powered anklet that retails for $750 and is designed to emit electrical pulses that are picked up by receptors in sharks' snouts.
Marine biologist and lead researcher Dr Ryan Kempster said the device was exposed to 395 encounters by 44 white sharks to test whether it could, as it claimed, deter sharks from up to 6m away.
But the study found white sharks "routinely" swum within 20cm of the "deterrent," and that it was no more capable when turned on than when turned off.
Given its limited range, the device could leave most of the wearer completely exposed to a shark attack, though researchers found sharks were about 30 per cent more likely to bump than bite users.
Dr Kempster said the anti-shark device was hampered by its "much smaller" size, and limited electrical field, and warned swimmers and divers to think carefully before investing in the technology.
"I would recommended that anyone interested in a shark-deterrent device do their research and only use devices that have been independently tested," he said.
"A YouTube video showing a shark turn away from a device does not count as research."
Marine biologist Dr Leonardo Guida, from Australian Marine Conservation Society, warned ineffective shark deterrents could be particularly dangerous, as they could give users a false sense of security.
He said the study proved there was an urgent need to test shark-deterring devices as any false advertising could lead to a "loss of human life".
"There are plenty on the market making claims, but they need to be tested," he said.
Researchers also noted that since completing the study, the ESDS device had been reissued under the NoShark brand, but "it was not clear" whether the device had improved.
UNPROVOKED SHARK ATTACKS 2019
New South Wales: 1
Western Australia: 1
UNPROVOKED SHARK ATTACKS 2018
New South Wales: 9
Western Australia: 7
Queensland: 3 (one fatal)
SOURCE: Taronga Conservation Society Australia