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Last Updated: Wednesday, 6 July, 2005, 12:28 GMT 13:28 UK
Electric shield to deter sharks
Great white shark
Some sharks have died in South African nets
Researchers in South Africa and Australia have started work on an electric shield to protect swimmers from shark attacks.

The shields emit an electric signal, which sharks do not like, so keeping them away from beaches.

Ebrahim Dhai from South Africa's Natal Sharks Board told the BBC that the electrical shields did not harm the sharks, just made them "uncomfortable".

Prototypes of this technology were used in the 2000 Sydney Olympics.

Triathletes swimming in Sydney harbour were protected by similar devices, Mr Dhai said.

They were also used by the Australian military and police force.

'No shark problem'

Personal devices have been on sale to divers, surfers and swimmers for the past three years, Mr Dhai said, but now they are working on erecting a string of them to protect an entire beach.

Surfer with shark shield
Devices to protect surfers are already on sale
"It will be trialled in South Africa within a year," he said.

Some South African shark conservationists are worried about the scheme, saying that the devices would hurt sharks.

"South Africa does not have a shark attack problem. It's always an adjacent human activity that leads to a shark attack," said Andy Cobb from South Africa's SharkProject.

But Mr Dhai said that a decade of trials "have shown that there is no harm to the sharks, human beings, or any sea creatures".

Sharks are the only sea creatures which are sensitive to electric signals because of nodules near their snout.

Some South African beaches are already protected by nets but sharks, dolphins and other creatures often get caught in these and some die.

"By having electronic devices, which would not harm any creatures, we could eliminate the nets," he said.

The shield would be placed about 400m out to sea and would be a string of electric emmitters, each with a radius of about 3m.


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