The first reaction to a shark attack is often a call for culling — but this practice is controversial for good reason.
Covering 70% of Earth and sinking deeper than an inverted Mt Everest, our oceans are a great unknown. We’ve only yet managed to map the sea floor to the same resolution as we have the surfaces of Mars and Venus; space has been a bigger target for exploration than our oceans. Quite simply, the depths of the oceans are out of our reach: the pressure is too great, the oxygen too low. To dive even to twenty metres assisted by scuba equipment and watch a stream of your bubbles meander to the surface through dappled sunlight, you quickly become aware of the weight of the water stacked on top of you. It can be claustrophobic.
But sharks, having adapted to their viscous environment as apex predators, roam the oceans with ease and humans, collectively, fear them immensely. Kids are in awe of sharks, just like they are dinosaurs, but we become afraid with age.
Fear is built layer upon layer, like sedimentary rock. Neuroscientist Joseph LeDoux describes fear as a fundamental human experience, a more complex psychological phenomenon than the mechanic fight or flight reflex. We are conditioned by repeated stimuli and we learn from what we are told or see. Human anxiety is also greatly amplified by our ability to imagine, forecast and question the future — and our fragile place in it. We commonly fear the unknown or what might come to be.
It’s not surprising we fear sharks. From Jaws to Finding Nemo, sharks have been portrayed as mindless eating machines — perhaps in part because of their programmed electrical sense that takes over from eye sight as sharks approach their prey — and our beautiful oceans, particularly here in Australia, are denounced as shark-infested waters.
Sadly, when tragedy strikes and a person is injured or killed by a shark, propositions of shark culls are often first off the press. Emotions are running high (understandably so) and many people want to see an immediate response — which a long-term scientific tagging and surveillance study is not. This has been the case in New South Wales and Western Australia in recent years, where broad shark culls were called for and trialled in the wake of numerous shark encounters.
In 2014, the WA government began catching and killing sharks after a string of shark-related fatalities between 2011 and 2012 in West Australian waters, using baited hooks and rifles at point blank range. Known as drumlines, buoys were placed offshore and anchored to the ocean floor with baited hooks to snag sharks. Large sharks over 3m when caught were killed immediately. Meanwhile, Queensland’s ‘shark control program’, which in 2014-15 saw over 600 sharks killed, has been running for 53 years.
The controversial ‘hunt and kill’ policy in WA sparked intense protest. The program was not preceded by an impact study to understand how culling practices may affect shark populations, and subsequently, the delicate ecosystems below them. Great whites are a species vulnerable to extinction in the wild, as rated by the IUCN Red List of Threatened Species, but the WA government sought exemption from their responsibility to protect listed species to legally institute the culling program. Of the 68 sharks killed during the three-month trial period of the policy in WA, none were great whites and the unintentional toll on other wildlife trapped in the lines was clear: only 28% of the animals caught during the program were the target species and size. Echoing the staunch opinions of ecologists and conservationists, shark culling was abandoned in WA after the state’s Environmental Protection Authority recommended that it not continue.
Dr Leah Gibbs, of the Australian Centre for Cultural Environmental Research at the University of Wollongong, NSW, studies people’s interactions with nature, focusing on the politics and processes of how we attempt to govern our environments. She considers shark cull strategies to be deeply misguided and ill informed.
“Unfortunately, there is no evidence that culling or killing an individual shark has any effect on reducing incidence of shark accidents,” Gibbs said. At best, it makes us feel safer — slightly. Only 8% of ocean users surveyed by Gibbs about the WA shark culling program agreed that the policy gave them a greater sense of protection and confidence in the water.
It’s important to weigh up the minimal effects of shark culling against the potential consequences. The implication of removing these ancient creatures from oceanic ecosystems is uncertain. Sharks are impressive animals, but elusive and poorly understood. What we do know is that several species live long and breed late. They have patrolled our oceans for more than 400 million years, surviving five major extinction events, including the one that wiped out dinosaurs.
What the media and entertainment industries don’t usually highlight is the beauty and diversity of shark species. Most are solitary creatures, except for hammerheads, which can swim in large schools during the day. Some species, like great whites and mako sharks, need to swim continuously to flush oxygen-rich water over their gills because they lack any evolutionary equivalent of a diaphragm. Only this year have scientist first captured footage of a great white shark ‘sleeping’.
Sharks are also incredible endurance athletes and have been tracked far across oceans. Scientists recently observed a lone great white (Carcharodon carcharias) that travelled more than 20,000 km from Gansbaai, South Africa, to the Exmouth Gulf in WA, and back again in less than nine months.
To navigate over long distances sharks likely follow gradients in the Earth’s magnetic field using a dense collection of electrosensory pores, called ampullae de Lorenzini, in their snouts. Their pores can detect subtle electrical currents, which run along charged particles in our salty oceans. Electric currents are induced by minute movements in the Earth’s magnetic field, or generated by the muscular movements in animals or fish. Another suggestion is that white sharks may also follow celestial cues since they spend considerably more time during transoceanic journeys just below the surface as if they’re looking to the stars.
A lack of understanding or appreciation of sharks ensures that fear is the strongest driver. Another issue is the heavy reliance on circumstantial evidence. Supporters of shark culling strategies may draw on anecdotal accounts of mounting shark sightings and encounters, claiming that shark populations are on the rise and that culls proactively remove ‘imminent threats’ to ocean users.
But there is no compelling evidence that shark populations are increasing. Instead, increased sightings may indicate changes in shark behaviour: it is possible that food supply for sharks has been depleted by overfishing and that murky polluted waters may be enticing larger sharks closer to shore. Are fluctuations in ocean temperatures due to climate change leading sharks into new coastal regions? Or perhaps the supposed increase is because ocean users are more alert and able to instantly share local sightings via smart phone apps.
Ocean users are usually the first to admit that they enter the ocean at their own risk. They respect the power of a shark and admire their beauty, describing a shark’s reflective skin, blue and dark. They’re pragmatic too: if a shark wants to eat you, you won’t see them, and if you do see them, they’re most likely not interested.
The majority of sharks encountered by surfers, ocean swimmers and divers are harmless species. Of the 500 shark species found throughout the world (180 of which are recognised in Australian waters), from majestic whale sharks, the largest of all fish, to the unicorn-like goblin shark, only four or so species are known to harm humans: white sharks, tiger sharks, bull sharks and some whaler sharks.
As Gibbs reported in her research, and likewise several polls in popular media, the majority of frequent ocean users are also against strategies that involve killing sharks, Instead, ocean users support further research and education focusing on shark behaviour and shark deterrents, as well as the implementation of warning systems, like the Shark Spotters program in Cape Town, South Africa, or the shark lookout program on Réunion Island, east of Madagascar, where divers, or vigies, patrol beyond the breakers to safe guard surfers and swimmers. In 2015, following 12 reported shark-related incidents on the NSW north coast and heated public debate, the NSW government opted for a shark surveillance and tagging program, which this summer will see the introduction of shark listening stations that detect the presence of tagged animals to alert the public via @NSWSharkSmart on Twitter.
There are also new technologies being developed for staying safe in the water. Some ocean users are now choosing to use personal shark deterrent technologies. Either with a strong magnetic field or electric current, shark deterrent technologies are portable devices designed to disturb sharks’ electroreception organs — like a sudden, intense headache — some of which have been shown to be effective against white sharks.
While fear of sharks can be intense, there are many larger dangers in this world. To put it bluntly, man is the greatest danger to man, when holding a firearm or at the wheel of a car. Comical statistics are also often quoted to ease people’s fear of sharks, say that vending machines are twice as lethal as sharks, but our emotive response overrides any rational assessment of risk, however slim the chance of being attacked by a shark may be.
Nevertheless, fear trumps admiration of these big fish. What frightens most is that no matter the threat, we can’t truly contain it — try as we might with shark nets. You see, a scarcely tested rivalry exists between humans and sharks: humans are the most dominant species on land and we’ve skilfully domesticated, contained or avoided any other large threats, but sharks — they remain the dominant predator of the sea. The truth is, despite any supposed ‘technical’ evolutionary superiority we may have, in the event of an aggressive encounter with a shark, humans are likely to come off second best. Sharks are a lethal reminder of our own mortality.
However, ocean lover or not, we do have a choice as to how we interact with our natural environment. We can give in to our fears, reap all that we can, the coal in the earth and the fish from our oceans, carve out our territory and push our planet to the brink, hoping that with some technological solution of our own ingenuity we can worm our way out of trouble at the final post. Or, we can begin by acknowledging our dependence on this earth and its ecosystems, adapt our behaviour, individually and collectively, and choose to conserve our planet as best we can.
Edited by Deborah Kane