Technology from South Africa installed in the Bahamas

The eco-friendly SharkSafe BarrierTM technology, developed by marine biologists at Stellenbosch University (SU) and their collaborators, and manufactured in the Western Cape, South Africa, has now been installed at a private island in the Bahamas.

The SharkSafe BarrierTM combines biomimicry of a kelp forest and magnetic fields to keep humans and sharks apart from each other without harming the sharks or large marine species.

According to Dr Sara Andreotti, marine biologist at SU and co-founder of SharkSafe BarrierTM, this nature-inspired technology is currently the only eco-friendly alternative to shark nets, which result in the death of thousands of sharks and other marine life every year.

The installation of a 30-metre long SharkSafe Barrier at the Berry Islands in August this year will further strengthen marine conservation efforts in the Bahamas.

In 2011 the Bahamas proclaimed the first shark sanctuary in the Atlantic Ocean, and, in 2018, a Marine Action Partnership (MAP) for Sustainable Fisheries. Shark tourism currently contributes approximately US$100 million per year to the local economy.

Dr Andreotti says since 2012 the technology has undergone rigorous testing in the turbulent ocean waters along the South African coast, as well as in the tropical waters of Réunion island and the Bahamas. The results from several of these case studies have been published in peer reviewed scientific journals.

The thinking behind the development of the SharkSafe BarrierTM concept is a combination of practical experience with sharks and marine biologists’ understanding of their behaviour, she explains.

Firstly, fish and other marine animals such as seals have been observed to use kelp forests as a hiding place from predatory sharks. By bio-mimicking a natural kelp forest, created by overlapping rows of plastic pipes anchored to the seabed, the SharkSafe BarrierTM has proven to be an effective deterrent for predatory sharks.

Secondly, marine biologists know that most shark species are sensitive to strong permanent magnetic fields because of the presence of electro-magnetic receptors at the tip of their heads. These small gel-filled pores – called ‘Ampullae of Lorenzini’ – are connected directly to sharks’ brains and allows them to register faint bioelectrical impulses dispersed in the water from their prey.

Using this knowledge, the developers of the SharkSafe BarrierTM created a strong magnetic field by inserting magnets into the kelp-like pipes. But instead of attracting the attention of a shark, the overly strong magnetic field over-stimulates the Ampullae of Lorenzini and therefore acts as another repellent. In other words, by inserting strong magnets into the kelp-like pipes of the barrier, it further strengthens the ability of the design to repel sharks, Dr Andreotti explains.

Today, the SharkSafe BarrierTM consists of high-density polyethylene pipes manufactured locally by KND Fabrications in Maitland, Cape Town. During installation in the ocean, the buoyant pipes are anchored on a grid-like structure one metre apart from one another, with large ceramic magnets staggered in the ocean-facing row. The grid is then weighted by limpet-shaped 200-kilogram cement blocks and secured by rock anchors and sand.

Apart from the fact that the SharkSafe BarrierrTM combines two proven shark repellent strategies, it has also been designed to remain in the water for at least 20 years with minimal maintenance required. This offers an opportunity for marine life to settle on the cement blocks which anchor the barriers to the seabed, forming an artificial reef.

For Dr Andreotti, the first commercial installation of the SharkSafe BarrierTM is the breakthrough that the team has been working towards for the past 15 years. “We now have the technology to allow the rightful inhabitants of the oceans to survive and thrive, and for sea-loving humans to enjoy their time in the water safely,” she says.

This is a win-win situation, especially for areas that rely on ocean recreation as a main source of revenue, such as beach towns in South Africa, Brazil, New Caledonia, the Bahamas and Réunion, she concludes.