Shark Shields: Electric, Chemical Repellents Show Promise

July 20, 2005

Recent shark attacks in Florida have sparked the now customary feeding frenzy in the media. Before Florida it was South Africa, where last month a medical student was eaten by a 16-foot (5-meter) great white near Cape Town.

Shark-conservation groups point out that you're more likely to be killed by a falling coconut than a shark. Nevertheless, coconuts don't have multiple rows of big, razor-sharp teeth, nor can they swallow you whole.

If our fear of sharks doesn't reflect the actual chances of being attacked, how do we put our minds at ease? When will it seem safe to go back in the water?

Scientists are developing coastal shark deterrents aimed at reducing both the risk of attacks and the perceived risk of attacks. The new tools include electronic beach shields and chemical repellents. Ironically, such deterrents could also help save sharks from even deadlier killers—humans.

Researchers are working on an electronic beach defense system aimed at preventing potential man-eaters from approaching people sporting in the surf. A prototype of this technology was used to safeguard triathletes competing in Sydney Harbour during the 2000 Olympics.

The electronic-shield project is a joint effort of the Natal Sharks Board in South Africa and SeaChange Technology.

SeaChange Technology, an Australian company, has already developed a range of personal shark-deterrent devices for professional divers and others. The equipment has proved effective against great white sharks, according to Natal Sharks Board biologist Sheldon Dudley.

The devices tap into the heightened sensitivity that sharks have to electrical fields. Dudley says humans and other marine creatures aren't bothered by low-level underwater electric signals, but sharks are.

"Our goal is to develop a beach barrier using similar technology," the biologist added.

Shark Shields

Some have criticized the proposed shark shields. For instance, Andy Cobb, of the Germany-based conservation group Sharkproject, described them as "unacceptable," saying they would cause unnecessary harassment of sharks.

But Dudley argues that electronic barriers are preferable to shark nets, which currently guard South Africa's more vulnerable beaches. He says these nets catch both sharks and marine animals that pose no threat to humans.

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