Since Western Australia announced its shark cull at the end of last year, the question of whether humans and sharks can ever really coexist has been thrust into the spotlight. As the cull continues, at great expense and with devastating effect on Western Australia’s shark population, perhaps it’s time to search for less archaic alternatives to making coastal waters safe not only for people, but also for the ocean’s most important apex predator.
Shark attacks undoubtedly have devastating consequences for the victims and their families, and every surfer, diver or swimmer should be able to enjoy the ocean in safety. But in reality, shark populations worldwide are in a steep decline, with the disappearance of over 90 percent of the planet’s sharks in the past 100 years alone. Methods as indiscriminate and destructive as the Western Australian shark cull are simply no longer viable. Removing the few remaining sharks from the ocean disrupts and threatens a fragile ecosystem, which provides food for a third of the world’s human population and generates more oxygen than all of the planet’s forests and rainforests combined.
Shark Culls and Shark Nets
Last year, there were a total of 10 fatal shark attacks worldwide. In that same year, humans killed over 100 million sharks, and although overfishing, shark finning and bycatch were largely to blame, shark eradication efforts in the name of human safety also played a role. The shark cull is an extreme version of another popular method of shark control, namely shark nets. The nets, like the cull, work on the idea that fewer sharks in the ocean means a lower likelihood of attacks. They are used predominantly in Australia and South Africa, and contrary to popular belief, do not prevent sharks from reaching beaches. Instead, they work by killing as many sharks as possible, which, upon becoming entangled in the nets’ large mesh, drown and die. In fact, shark nets like the ones in Australia and South Africa, along the New South Wales and KwaZulu-Natal coastlines respectively, neither reach the seafloor nor the surface but are suspended in between the two. Sharks are able to swim over, under and around the nets, which not only explains why 35 to 50 percent of sharks caught in Australia are entangled on the beach side of the net, but also throws into question the nets’ effectiveness in protecting swimmers at all. They are, however, extremely effective in killing sharks. In the last thirty years, South Africa’s nets alone have been responsible for the deaths of over 33,000 sharks, 25,000 of which were harmless species. In addition, the nets ensnare turtles, rays, whales and dolphins, which damages populations and negatively impacts the country’s thriving dive-tourism industry. Two of the three shark species intentionally targeted by South African nets are the great white and the tiger, yet studies conducted in 2003 and 2009 show that operators offering great-white encounters bring in approximately $4.2 million each year, while the tiger-shark diving business brings in another $1.7 million. Reducing the populations of these species consequently has a devastating impact on an increasingly lucrative industry; at the same time, the South African nets cost taxpayers approximately $5.3 million every year to maintain. Similarly, a recent review of Western Australia’s shark cull showed that to date, the program has cost around $1.2 million. Clearly, outdated methods like shark nets and shark culls are not only costly to the environment, but quite literally as well.
Effective Alternatives
There are several alternatives to shark nets and shark culls, which are both effective and infinitely more acceptable from a conservation perspective. Scientists from the University of Stellenbosch in South Africa have developed a shark barrier that uses magnetic fields instead of nets to repel sharks rather than kill them. The technology is based on sharks’ ability to detect electrical impulses and magnetic fields with a series of sensory receptors on their snouts known as ampullae of Lorenzini. According to Dr. Sean Fennessy, one of the scientists involved in the creation of the Sharksafe barrier, “sharks reportedly have the greatest electrical sensitivity of any animal.” The barrier, which is designed to resemble a kelp forest and involves magnets placed in Perspex tubes, emits a strong magnetic field that researcher Craig O’Connell believes causes the shark temporary discomfort, encouraging it to swim away. The product has been tested on both bull sharks and great whites, using bait to try and entice the sharks to cross the barrier. During testing off Dyer Island in South Africa, 60 great whites were exposed to the barrier, and not one crossed from one side to the other. Portable devices known as shark PODs, or shark shields, employ similar technology by emitting electromagnetic fields, and can be strapped to a surfboard or to a freediver, snorkeler, or scuba diver to protect them from shark attack.
Other possible alternatives include shark enclosures or exclusion nets, like those tested in 2013 in Cape Town. Unlike traditional shark nets, which are designed to kill sharks, exclusion nets form a physical barrier separating enclosed areas from the open ocean, extending from shore to shore and from the surface to the seafloor. They’re constructed of a fine mesh that prevents marine entanglement, and are deployed and retrieved on a daily basis to ensure that they’re still intact. After 14 months, the shark nets deployed at Fish Hoek in Cape Town were deemed a success: great whites entered the bay 18 times during that period, but did not attempt to breach the barrier, while the nets caused just one casualty, a single entangled Cape cormorant.
Cape Town is the home of another shark mitigation initiative called Shark Spotters, wherein people watch for sharks entering popular bays from a vantage point using binoculars and polarized sunglasses, while maintaining radio contact with a second spotter on the beach. The team uses a flag system to notify swimmers and surfers of shark activity in the bay — red to indicate high alert, white to indicate that a shark has been spotted, black for when conditions prevent effective spotting and green for all clear. After a spate of fatal shark attacks in Recife, Brazil, the government implemented a system whereby dangerous shark species were relocated away from coastal areas by catching them and releasing them further offshore. The program saw a 97 percent decline in shark incidents, ensuring human safety while impacting local shark populations minimally.
That there are so many alternatives to destructive shark mitigation methods like netting and culling proves that it’s possible for sharks and humans to coexist in the ocean. It’s also important to remember that no attempt to control nature can ever be fully guaranteed, and watersports enthusiasts should educate themselves about shark behavior before entering the water to further reduce the likelihood of attack.
Statistics from the International Shark Attack File show that an individual’s risk of being killed by a shark is 1 in 11.5 million. But the risk for all of us, to not only our future, but also to that of our oceans and ultimately our planet if we do not stop killing sharks arbitrarily, is a far worse threat.
