Cape Times reported on Wednesday that the study tested a popular local shark shield, a device strapped onto the ankle to emit electronic waves uncomfortable to a shark's delicate senses.

Shark ecologist Charlie Huveneers tested the shield for over two years, using tuna bait at the Neptune Islands off Australia and seal decoys in False Bay, Cape Town.

He told the newspaper that he found no difference in the proportion of bait consumed, regardless of whether the device was activated.

Local shark scientist Alison Kock, who collaborated with the local part of the study, said results showed the shields worked under some conditions and not others.

"In South Africa we found significantly fewer predatory strikes on the seal decoys, but in Australia it didn't stop the sharks getting the bait and coming very close to the device."

The shield did, however, increase the distance at which white sharks turned away from the tuna bait.