Electronic cable tested as a shark barrier in South Africa

Scientists in South Africa are using an underwater electronic cable to repel sharks in an experiment that aims to protect swimmers and surfers without harming marine animals.

A 100-metre long cable has been placed on the seabed and will emit a low frequency electronic field that has been proven to repel the predators.

Sharks are more sensitive to electric fields than any other animal due to electroreceptors in their noses that help them hunt by detecting muscle contractions in their prey.

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"The technology is really specific in that it targets a sense that only sharks and rays have. Mammals like dolphins and whales don't have a sense like this, so they are not going to be affected," Alison Kock, a biological scientist and research manager for Shark Spotters in Cape Town told AFP.

The method is being trialled in the bay of Glencairn beach in Cape Town, where sharks frequently appear during the summer months. Researchers will observe the results for five months, before deciding if the practice should be extended.

"If successful, it will provide the basis to develop a barrier system that can protect bathers without killing or harming sharks or any other marine animals," says the KwaZulu-Natal Sharks Board, the organisation responsible for the project.

The board is also responsible for developing a 'shark pod', which emits a similar electronic field to protect commercial divers.

Scientists say the electronic field will have little impact on humans who come into contact with it as it will only cause a slight "tingling sensation".

Shark nets have been used along the South African coastline for over five decades, but have been criticised for causing the deaths of sharks and other marine animals. The nets have killed 470 sharks every year between 2006 and 2010, according to The Times.

"Everyone is 100 per cent behind this project from the government to environmentalists, because this means we will have fewer sharks ending up dead from being trapped and tangled in the shark nets," Paul Von Blerk, the board's technology specialist told Reuters.