Revolutionizing the concept of shark management

Shark-specific barrier technology developed by marine biologists from Stellenbosch University (SU) and their collaborators has been installed in the Bahamas by a client with a private island in the Bahamas.

In 2011, the Bahamas proclaimed the first shark sanctuary in the Atlantic Ocean and, in 2018, a Marine Action Partnership for Sustainable Fisheries. The installation of the 30-metre-long SharkSafe Barrier^TM along a bay on one of the islands will further strengthen marine conservation efforts in the region.

The SharkSafe Barrier^TM combines biomimicry of a thick kelp forest and magnetic fields to keep humans at bay from sharks without harming them or any other large marine species. Biomimicry is a practice that learns from and mimics the strategies found in nature in order to solve challenges in the human world.

The nature-inspired SharkSafe Barrier^TM technology, 15 years in development, is currently the only eco-friendly alternative to shark nets. The latter "walls of death", in use since 1950, are not shark specific and kill thousands of harmless sharks, whales, dolphins, sea turtles, and large bony fish every year. According to new data published by the government of New South Wales, almost 90% of marine animals caught in shark nets along this Australian state’s coast over the past year were non-targeted species.

Dr Sara Andreotti, extraordinary lecturer in marine biology at SU and a founding director of SharkSafe Barrier^TM, says the kelp-like forest created by their barrier technology has been designed to remain in the water for at least 20 years with minimal maintenance required. Eventually, it changes into a reef-like haven for local sea life.

The barrier has been tried and tested extensively in South African coastal waters — from those crashing on the rough, rocky shores of Gansbaai to the sandy beaches of Glencairn — as well as in the tropical waters of Réunion island and the Bahamas. However, the SharkSafe Barrier^TM in the Bahamas constitutes the first commercial installation of this technology. Andreotti is now working with coastal municipalities in South Africa to develop alternative funding mechanisms for installation locally, as well as with municipal authorities in Australia and New Caledonia.

Rooted in research

The roots for the development of the SharkSafe Barrier^TM can be traced back to Andreotti’s doctoral research on the population numbers and genetic diversity of South Africa’s great white shark (Carcharodon carcharias). Between 2009 and 2011, she conducted the largest yet field research study on this species with the help of the shark conservationist Mark Rutzen. They lived at sea for up to two months at a time to count and collect biopsies from these sharks for genetic analysis.

At the time, the results from Andreotti’s doctoral research painted a bleak picture. Not only did the great white shark population along the South African coastline display the lowest genetic diversity of all such shark populations worldwide, there were also only between 353 and 522 individuals left. According to Andreotti, this was 52% lower than what was estimated in previous mark-recapture studies.

“If the situation stays the same,” she warned during a media conference in 2016, “South Africa’s great white sharks are heading for possible extinction”.

Among the possible reasons identified for the sharp decline in great white shark numbers was the impact of shark nets and baited hooks implemented on the eastern seaboard of South Africa. Between 1978 and 2008, for example, about 1 063 great white sharks were killed due to shark protection measures alone. Other contributing factors were poaching, habitat encroachment, pollution, and depletion of their food sources.

In the face of these alarming results, Andreotti, Rutzen and Prof Conrad Matthee from SU's Department of Botany and Zoology realised they needed to find an alternative to shark nets — something that would make beaches safer for bathers and sharks alike.

Inspired by nature

“The thinking behind the development of the SharkSafe Barrier^TM was based on a combination of practical experience with sharks and our understanding of their biology and behaviour,” Andreotti explains. Firstly, Rutzen observed how fish and other marine animals such as seals use kelp forests to hide from predatory sharks. This is when the idea of biomimicking a natural kelp forest originated.

This knowledge of marine animal behaviour was combined with existing research on the use of magnetic fields to deter sharks. Most shark species are sensitive to strong, permanent magnetic fields because of the presence of electromagnetic receptors on 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 by their prey.

Instead of attracting the attention of a shark, the biologists reasoned, a strong magnetic field would overstimulate the Ampullae of Lorenzini and have the opposite effect. In other words, by inserting strong magnets into the kelp-like pipes of the barrier, it would further strengthen the ability of the design to repel sharks.

The concept was registered as a patent in 2012 through SU’s technology transfer company Innovus. In 2014, the SharkSafe Barrier^TM company was commercialised. That was when the real work started. For the past decade, Andreotti has been working with marine engineer Laurie Barwell and other individuals and organisations to not only develop a business model that will attract investors but, first and foremost, to perfect the technology behind the barrier through rigorous testing in South Africa’s turbulent oceans.

Today, the SharkSafe Barrier^TM 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.

In 2020, the SharkSafe Barrier^TM company really took off when the barrier design was labelled a Solar Impulse Efficient Solution and selected as a finalist in the Smart Eco-Responsible Tourism category of the Tech4Island Awards. In the same year, the inventors of the SharkSafe Barrier^TM technology also received the prestigious NSTF-Lewis Foundation Green Economy Award at the NSTF-South32 Awards function. In 2021, the company was recognised by the World Economic Forum’s digital platform UpLink as one of its top ocean innovators.

Revolutionising the concept of shark management

For Andreotti, the first commercial installation of the SharkSafe Barrier^TM 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, and Réunion. In the past, negative encounters with sharks have had adverse effects on local economies.

In April this year, Conservation International’s CI Ventures invested US$250 000 (roughly R4,7 million) in SharkSafe Barrier^TM. According to Gracie White, lead of Global Ocean Investments for CI Ventures, lethal control measures for managing sharks are outdated. “It’s time to modernise, for both marine biodiversity and human well-being,” she said in a recent statement.

Hopefully, it’s not too late for South Africa’s great white sharks. According to Andreotti, these sharks have been counted using manual photographic identification in only three studies, the last of which was conducted about a decade ago. “In two of the three studies, it was estimated that there were fewer than 500 sharks left. A more recent study indicated that even the very conservative levels of human-related removal of great white sharks may be sufficient to drive abundance decline, and new mitigation measures may be required to ensure population recovery.

“In contrast, studies based on unconfirmed sightings always risk overestimating the status of the local populations,” she warns.

“We cannot continue to waste time by debating whether the removal of a few individuals by orcas in our local waters could have impacted this population significantly more than decades of human-related, targeted removal with shark nets and drumlines, and the adverse side-effects of bycatch and overfishing of their food resources.

“My fear is that these animals will simply go extinct on our watch.

“It is time”, she says, “for a revolution”.