A new eco-friendly shark barrier is being tested in Cape Town

Great news for Cape Town divers and other water users: a safe, eco-friendly shark barrier, is proving effective at curbing shark attacks, says Lynne Fraser, scuba diving instructor and former editor of South African dive magazines The Divesite and Divestyle.

Researchers from Stellenbosch University have developed a new method to potentially curb shark attacks that is safe for sharks, humans and other marine life.

The researchers worked with Michael Rutzen, the owner of Shark Diving Unlimited, a cage diving company based in Gansbaai, who is also known as “Shark Man” because he freedives with great white sharks. Together Rutzen and the university researchers have developed a new eco-friendly, non-invasive solution to shark nets that will potentially curb shark attacks. The system, called Sharksafe, is currently being tested in South Africa’s shark cage diving hotspot, Gansbaai, a two-hour drive east of Cape Town.

The system consists of PVC pipes fitted with permanent magnets that are anchored to the seabed, and which move in the water like kelp (seaweed). The system works on two levels: one, sharks – great whites in particular – tend to avoid swimming through kelp; and two, the magnetic field overwhelms their sensory systems, which effectively repels them. The magnetic field only affects sharks and poses no known threat to seals, humans, turtles, dolphins and other marine life. An added benefit is that animals don’t get entangled, as they do in conventional shark nets.

The Sharksafe barrier was deployed for the first time in 2012 in Gansbaai’s Shark Alley, an adventure diving hotspot and one of the best locations on the planet to study great white shark behaviour. While building the underwater barrier the team was observed by several curious white sharks that patrol the area!

Besides using permanent magnets as shark deterrents, the Sharksafe barrier is designed to mimic the kelp forest, with three to five rows of large vertical pipes that create a device that can manipulate the swim patterns of white sharks. The magnets specifically target the electrosensory system of elasmobranches (which includes sharks and rays); other marine life, like the Cape fur seal, is unaffected and can swim through it with ease.

Once the system was deployed, the researchers – who included a team of divers – surveyed the artificial reef that had started to form on the concrete bases of the barrier, and then chummed through it to collect behavioural data on the white sharks. Over two years of observation (in 2012 and 2013) it was seen that the Sharksafe barrier successfully altered the swimming behaviours of the great white sharks and provided an effective barrier.

The key to a sustainable ecosystem and healthy planet is to keep our long-term goals in mind: we must consider the consequences of our actions now, and how they may impact future generations. Sharks are an integral part of our oceans and the time has come to employ eco-friendly and sustainable technology that will encourage the co-existence of humans and sharks in the same waters.

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