‘Plastic kelp’ to keep sharks at bay
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Cape Town - The developers of a new shark barrier system are hoping to secure funds to deploy an experimental barrier off a beach, to test its effectiveness as an eco-friendly alternative to shark nets.
The “Sharksafe” barrier is designed to deter sharks, using a combination of permanent magnets and an artificial “forest” of plastic pipes that look like underwater kelp (sea bamboo).
Writing in the Journal of Experimental Marine Biology and Ecology, the developers said experiments near Gansbaai in the Western Cape had shown promise and could provide the foundation for further research.
Craig O’Connell, a marine scientist from the University of Massachusetts Dartmouth and founder of O’Seas Conservation Foundation, said the research aimed to develop shark exclusion barriers to replace shark nets and other lethal bather-protection systems used in KwaZulu-Natal and Australia.
KZN Sharks Board statistics show an average of 460 sharks die every year in the province’s bather protection nets, along with dozens of turtles, dolphins, rays and sea birds.
Unlike shark nets and drum lines, designed to catch large sharks, the Sharksafe barrier aims to deter sharks from coming into contact with swimmers by repelling them.
This is done with a combination of barium-ferrite permanent magnets and barriers made of long rows of PVC pipes anchored to the sea floor. The pipes have special joints that allow them to move in the currents and waves.
O’Connell and fellow researchers, including Professor Conrad Matthee and Sara Andreotti of the University of Stellenbosch and Michael Rutzen of Shark Diving Unlimited, say the idea of using plastic pipes was based on observations that seals often flee into thickets of kelp to avoid being eaten by sharks.
A year-long series of 49 hour-long trials involving more than 60 sharks showed none swam through the magnetised and non-magnetised barrier sections, despite being lured with fish chum.
l Geremy Cliff, head of research at the KZN Sharks Board, has not responded to requests for comment.