Sarah Wild, Shark magnetic barriers, Reunion
  • A South African start-up has developed a shark barrier that the ocean predator will not cross.
  • It is made out of magnets and a fake kelp forest, and Reunion Island’s Shark Risk Reduction Resource and Support Center is testing it in the beach-goers paradise. It is also in Gansbaai in the Cape.
  • Great white sharks are vital for ocean ecosystems, but they are under threat – mainly from humans.

A South African invention is right now being tested on Reunion Island, with a view to protecting beach-goers without killing sharks and other marine life. The SharkSafe Barrier is a non-harmful way of keeping sharks away from humans.

The barrier is made out of tubes containing strong magnets, and biomimics a kelp forest to visually deter sharks. Sharks are able to detect magnetic fields, thanks to sensory organs called ampullae of Lorenziniin their heads. These ampullae are a highly sensitive network of tiny jelly-filled pores that allow sharks to sense electromagnetic changes.

Sarah Wild, Shark magnetic barriers, Reunion

In waters off Gansbaai in the Western Cape, there was a 15m by 15m square circumscribed by a SharkSafe Barrier that no shark has crossed in the two years of testing — even though there was food inside it. “In all the years of experiment, they never crossed it,” says Sara Andreotti, one of the inventors. And it wasn’t just great white sharks, but also bull, tiger, and hammerhead sharks.

The start-up, SharkSafe Barrier Pty Ltd, is being spun out of Stellenbosch University, thanks to R1-million in seed funding from the Technology Innovation Agency. The barrier units are made by Cape Town company Labscheme Allchem.

Sarah Wild, Shark magnetic barriers, Reunion

The Reunion Island installation is first time that the company is installing the technology outside of South African waters, as the island — through its Shark Risk Reduction Resource and Support Center — explores ways to curb its shark problem. The island has seen a giant spike in the number of shark attacks in recent years. From 2007 to 2016, the island saw seven fatal attacks (and 14 non-fatal); while South Africa experienced 13 fatal attacks and 28 non-fatal ones, according to International Shark Attack File. For some context, Reunion’s coastline is about 207km, which is less than a tenth of South Africa’s 2,500km sprawling coast.

Most shark-safety initiatives involve nets or drumlines, which are baited hooks. The KwaZulu-Natal Sharks Board, for example, has 37 shark nets and 107 drumlines that stretch across the coast line.

Sarah Wild, Shark magnetic barriers, Reunion

“Between 2011 and 2016, there have been 491 registered shark attacks worldwide, of which 43 proved to be fatal,” Andreotti has said. “Over the past 20 years, however, almost 4,000 sea creatures have been in shark nets lining the beaches of New South Wales in Australia alone.”

There has been a move towards non-invasive ways to keep sharks and people separate. In Cape Town, the Shark Spotters programme has people watching the ocean, ready to alert swimmers to the presence of sharks.

However, sharks are under threat — mainly from humans, although killer whales are now also tearing into the South Africa’s great white shark numbers.

Sarah Wild, Shark magnetic barriers, Reunion

Research on South Africa’s great white shark population — undertaken by Andreotti as part of her doctorate at Stellenbosch University — found that the population has particularly low genetic diversity. Genetic diversity is important because it indicates a population’s resilience: if there is an environmental change or if a disease sweeps through the population, it will be more likely to survive if there is greater genetic diversity.

The more sharks that die in nets, the more diluted that diversity gets.