CAPE TOWN // In the blue waters of a small bay in Cape Town, a revolutionary experiment with an electronic barrier is seeking to exploit the super-sensitivity of a sharks’ snout to keep swimmers and surfers safe.
A high-tech version of the reputedly life-saving punch to a shark’s nose is being tested in an effort to protect humans without harming the predators or other sea creatures.
The technology has been developed by South African experts who invented the electronic “shark pod” for use by surfers and divers and could be applied globally if successful.
The pod and years of research have shown that sharks will turn away when they encounter an electrical current, prompting a much larger scale of the experiment.
A 100-metre cable with vertical “risers” designed to emit a low-frequency electronic field is in the process of being fixed to the seabed off Glencairn beach, and will remain there for five months.
“If successful, it will provide the basis to develop a barrier system that can protect swimmers without killing or harming sharks or any other marine animals,” said the KwaZulu-Natal Sharks Board, which developed the shark pod.
As for humans, “if someone touched the small part of an electrode that is exposed, they might experience a tingling sensation” but would suffer no harmful effects.
The barrier would mark a major shift away from the shark nets used in KwaZulu-Natal on South Africa’s east coast for the past 50 years, which also kill other animals and have been criticised as environmentally destructive.
Research has shown that sharks have a gel in their noses which makes them more sensitive to electrical currents than other species, and thus ordinary fish and sea life such as seals and dolphins should not be affected by the barrier.
“We are doing our best to do something environmentally friendly,” said Paul von Blerk, a sharks board project specialist.
But challenges remain.
“It is easier to design things to put in space,” said Claude Ramasami, from the Institute for Maritime Technology, which is helping the sharks board put its plans into practice.
This is because of the relentless power of the sea, shifts in the seabed, undersea structures and marine life – and simply using electricity in water.
One reason that Glencairn in the Cape was chosen as the site for the experiment is that it is relatively protected.
The clear waters will also enable fixed cameras and shark spotters to monitor the movements of the predators within the bay and see whether the barrier turns them away from their usual cruising routes.
In a 25-day observation period, 53 sharks have already been spotted off the beach.
Environmentalists have welcomed the experiment.
Alison Kock, a biological scientist and research manager for Shark Spotters, said, “It’s an exciting opportunity to look at new technology with the ultimate aim of replacing lethal control methods like shark nets and [baited] drum lines.”
“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,” she said.
The gel in the noses of sharks allows them to detect minute electrical fields such as a heartbeat to find prey in murky water, but as they approach within a couple of metres of the barrier the power should be enough to turn them away.
WWF was “absolutely supportive of interventions which attempt to manage human-animal interaction in a non-fatal and non-impactful way”, said John Duncan from the organisation’s marine programme.
Sharks have killed 13 people in South Africa over the past 10 years, Ms Kock said.
* Agence France-Presse