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Inspired by Nature
SA-made nature-mimicking shark-barrier tech scores first commercial installation
The ecofriendly SharkSafe Barrier technology, developed by marine biologists at Stellenbosch University (SU) and their collaborators, and manufactured in the Western Cape, has been installed at a private island in the Bahamas in its first commercial deployment.
The SharkSafe Barrier combines the biomimicry of a kelp forest and magnetic fields to keep humans and sharks apart, without harming the sharks or other large marine species.
According to Dr Sara Andreotti, marine biologist at SU and cofounder of SharkSafe Barrier, the technology, inspired by nature, is currently the only ecofriendly alternative to shark nets, which result in the death of thousands of sharks and other marine life every year. She believes the installation of a 30-m-long SharkSafe Barrier at the Berry Islands 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, it announced a Marine Action Partnership for Sustainable Fisheries.
Shark tourism currently contributes about $100-million a year to the local economy.
What is the SharkSafe Barrier?
Andreotti says the technology has undergone rigorous testing in the turbulent ocean waters along the South African coast since 2012, as well as in the tropical waters of Réunion island and the Bahamas.
The thinking behind the development of the SharkSafe Barrier 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 Barrier 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 electromagnetic receptors at the tip of their heads.
These small gel-filled pores – called ‘Ampullae of Lorenzini’ – are connected directly to sharks’ brains and allow them to register faint bioelectrical impulses dispersed in the water from their prey.
Using this knowledge, the developers of the SharkSafe Barrier created a strong magnetic field by inserting magnets into kelp-like pipes.
But, instead of attracting the attention of a shark, the overly strong magnetic field overstimulates the Ampullae of Lorenzini and therefore acts as a repellent.
Today, the SharkSafe Barrier consists of high-density polyethylene pipes manufactured locally by KND Fabrications in 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 oceanfacing row.
The grid is then weighted by limpet-shaped 200 kg cement blocks and secured by rock anchors and sand.
The installation has been designed to remain in the water for at least 20 years with minimal maintenance required.
This allows marine life to settle on the cement blocks that anchor the barriers to the seabed, forming an artificial reef.
For Andreotti, the first commercial installation of the SharkSafe Barrier is the breakthrough 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.”