An electronic device designed to ward sharks away from surfers failed so spectacularly during a trial off South Africa that it was eaten by a great white.

Hungry shark
©Barcroft Media

An inquest heard yesterday the Shark Shield surf model was activated on a float carrying bait when the 3.6m female shark approached. Rather than being deterred by the device, the shark, under the gaze of the Natal Sharks Board, bit into it.

South Australian Deputy State Coroner Tony Schapel yesterday heard of the test failure during the inquest into the death of Jarrod Stehbens, who was taken by a great white shark while diving off Glenelg in South Australia in 2005.

The inquest has turned into a trial of Shark Shield devices, hearing concerns that the electronic fields generated to repel sharks may attract them.

Studying cuttlefish for the University of Adelaide at the time of his death, Stehbens had been provided with two Shark Shields on his dive boat by university staff - but he either didn't know they were there or chose not to use them.

University staff have told Mr Schapel they questioned the Shark Shields' efficacy and believed there might be long-term health risks from using them. As a result, the devices were not compulsory.

Rod Hartley, director of Sea Change Technology, which manufactures the Shark Shields, yesterday took the stand to defend his product.

"There is no doubt whatsoever that it does not attract sharks," he said.

He told Mr Schapel he believed a disgruntled surfer had started the rumour.

"Nobody wearing a Shark Shield has ever been attacked by a shark," he added.

Mr Hartley said the failed South African test on the surf unit - which has been held back from release into the marketplace - was due to a problem with the electrode's configuration. The device was now packaged with a large disclaimer warning it would only repel sharks when the surfer was still in the water waiting for a wave.

"The surf product only can be guaranteed to work when it's stationary, not when it's surfing in the wave or paddling," Mr Hartley said.

Comment: So this device will only work to repel sharks as long as you're not actually moving in the water, e.g. swimming, surfing, treading water. And it could actually attract sharks. Sounds like a lot like many of the other things we're sold, e.g. aspartame, water fluoridation, antidepressants, etc.

CSIRO shark expert Barry Bruce has told the inquest the shark that killed Stehbens was in "full predatory strike" mode and would have been nearly impossible to deter. His body was never recovered.

Mr Schapel will publish his findings at a later date.