Shark! Technology to help prevent ocean attacks
They’re big and bitey and occupy a unique place in our subconscious, but how is technology helping to protect human ocean-goers from shark attack, and at the same time improve our understanding of this 420 million-year-old fish?
Well-known shark species such as the great white, tiger, blue, mako, thresher and hammerhead are apex predators, at the very top of their underwater food chain. Today, however, sharks are under ever-increasing pressure with many populations threatened by human activities. Therein lies the rub.
Records of shark attacks in Australia have been kept since the early days of European settlement, with the first attack recorded in 1791. In an effort to standardise reporting, the Australian Shark Attack File (ASAF) was developed in 1984 by the Taronga Conservation Society Australia. A report by ASAF coordinator John G. West on attacks up to 1990 suggests that unprovoked shark attacks per decade had slowly declined and remained relatively stable after shark management practices were introduced around Sydney in the 1930s.
Although infrequent, shark attacks attract great public and media interest, provoking our fascination and horror in equal measure. Despite this, however, the actual risk of a fatality from a shark attack in Australia is still low when compared to other types of marine-based deaths. With no evidence of increasing shark numbers influencing a recent rise in attacks, a look at ASAF trends - particularly over the last two decades - actually reveals that what has changed over time is the way in which people use the ocean.
According to West, a significant rise in Australian shark attacks, from an average of 6.5 incidents per year in 1990 to 2000, to 15 incidents per year over the following decade, rising to 23 in 2014, and 26 in 2016, coincides with an increasing human population, more people visiting beaches, a rising popularity of the coastal lifestyle and the marine activities that come with it, and the increased accessibility of previously isolated coastal areas.
A spate of fatal shark attacks in Western Australia has seen seven deaths over the last three years, with the most recent occurring in April 2017. When a teenage surfer was attacked by a great white shark, it became the third deadly attack in the state over a 12-month period.
This high number of attacks has reignited the shark cull debate and put a spotlight on methods of prevention, with Josh Frydenberg, the state’s Federal Environment Minister, saying he would consider culling alongside the newest drum line technology and shark exclusion nets. Interestingly, amid beachside protests and controversy at the proposal to cull, the state government has said it prefers the use of personal devices, known as shark shields, to culling or drum lines.
Shark shields - a device which emits an electrical field to repel sharks and is attached to a person’s ankle or surfboard – fall within a raft of new shark attack prevention methods, or shark mitigation strategies (to use the correct term), that employ the findings of scientific research into shark behaviour, combined with the innovative use of technology, to achieve a more effective, preventative approach, as opposed to the random killing that culling, baiting and nets entail.
The ability to sense electrical stimuli is an ancient sensory capability present in all Elasmobranchs, the subclass to which all sharks, skates and rays belong. Sharks detect electromagnetic fields in the Ampullae of Lorenzini, clusters of multiple nerve fibres in gel-filled canals in the head, opening to the surface via pores and functioning as independent receptors. Besides the detection of prey, predators and mates, the system is also believed to help sharks navigate using the Earth’s electro-magnetic fields.
These highly sensitive receptors can detect electrical fields at voltages as low as five nV/cm (five one-billionths of a volt per centimetre), making the shark an impressive stalker. Make that electrical pulse sufficiently powerful, however, and that same sensitivity becomes disorientating and even physically painful, causing muscular spasms that are enough to deter the big fishy.
Researchers have been investigating whether the electro-receptive capabilities of sharks can be used to repel them from humans since the 1960s. Research carried out in the 1990s and early 2000s by the KwaZulu-Natal Sharks Board, a South African organisation tasked with protecting ocean-goers from shark attacks, confirmed that electroreception could be used to deter sharks without causing them any harm and culminated in the first-generation of technology based on this method – the SharkPOD, a small device comprised of two electrodes, placed on the oxygen tank and ankle, and aimed primarily at scuba divers.
Fast-forward some two decades and the latest generation of this electronic shark deterrent system is known as Shark Shield and expands on the capabilities of the original model. Developed by Australian company SeaChange Technology Pty Ltd and commercialised by its trading arm Shark Shield Pty Ltd, established in October 2006, the latest incarnations of Shark Shield include Freedom7 for free-diving, spearfishing, scuba diving or kayak fishing; Scuba7 for the scientific, military and technical diving markets; and Freedom+ Surf designed for all surfing activities.
The basis behind all of its applications is a device consisting of an electronic control unit, typically attached to the ankle of the user, with a 2.2m-long flexible mesh, trailing antenna. The antenna contains two elongated electrode plates separated at its ends approximately two metres apart. When the device is turned on, sea water surrounding the electrodes acts as a conductor and an electric circuit is completed forming an electric field that surrounds the user and is repellent to sharks (fingers very tightly crossed).
The Shark Shield, and its former version, the SharkPOD, is the only electric deterrent to have undergone any form of robust scientific scrutiny. A report published in July last year outlined the findings from the most recent study, funded by the University of Western Australia’s Oceans Institute together with the West Australian State Government Shark Hazard Mitigation Applied Research Program.
Using a modified stereo-camera system, behavioural interactions between great white sharks and a baited target were quantified in the presence of a Shark Shield. Such measurable evidence revealed that a Shark Shield positioned in close proximity to a surface decoy was sufficient enough to affect the behaviour of great white sharks and reduce surface interactions by 92.6 per cent.
Such is the confidence in Shark Shield technology that the Western Australian state government has endorsed its efficacy by offering a subsidy of A$200 to anyone wanting to buy one and the device continues to be developed with its newest iteration a long-range version of the technology. Shark Shield business development manager Hudson Lyon explains: “Our newest technology is called Ocean Guardian and uses a patented metamaterial electromagnetic transducer, creating a propagation wave with the capability of repelling sharks within a 100m diameter of each unit installed.”
The new transducer form is based on technology used to treat patients in the medical field, with clinical studies demonstrating that the electromagnetic field does not affect the health of humans or ocean life. In addition, the electromagnetic field shape removes the need for the construction of net-style barriers, either electrical field or traditional netting.
In the Australian government’s rush to consider “any proposal to put human life first”, traditional methods have included systems that pose a direct threat to marine life. Culling with the use of drum lines comprises a trap consisting of large baited hooks attached to a floating object, which is anchored to the sea floor.
However, like shark nets, they don’t discriminate as to the species caught and result in by-catch, the killing of untargeted, and often threatened species, such as sea turtles, dugongs, dolphins and whales, along with other harmless species. Drum lines are not even particularly effective at catching great white sharks, one of the three main species responsible for unprovoked shark bites.
A greater understanding of the important role that sharks play in the structure and function of marine ecosystems, as well as an increasing conservation focus, has resulted in strong public opposition to the use of these methods and a surge in interest in finding alternatives.
Some beaches are now using drones in conjunction with normal beach patrols and monitoring as a more accurate way of spotting sharks. A three-month trial of drone surveillance starting in November 2016 was implemented on West Australian beaches to monitor shark activity and garner a greater knowledge around the movement of schools of bait fish which attract predators into the beach. The A$88,000 trial provided a small drone equipped with a high-definition camera to stream live pictures back to Surf Life Saving WA operators at metropolitan and regional beaches with the aim of greatly improving the situational awareness of their beach surveillance.
Smart drumlines are another technological alternative to a traditional method, first developed on the tiny island of Réunion, a French territory in the Indian Ocean which, according to the University of Florida’s renowned International Shark Attack File, was responsible for over 16 per cent of the world’s fatal shark attacks between 2011 and 2017. Unlike traditional aquatic traps, or drum lines, which kill everything that they lure in, smart drum lines alert authorities when a shark is captured so that they can be tagged and relocated, with around 90 per cent of animals caught surviving to swim another day.
Facial-recognition software is also being used in the high-tech armoury becoming available to us in deterring our finned friends - and you don’t even have to get close enough to recognise their faces! Sonar buoys are using the same technology to detect and identify sharks, before relaying a message to public safety bodies on the beach.
Shark Mitigation Systems Ltd (SMS) is an Australian company based in Perth, focused on developing scientific, non-invasive solutions to mitigate shark attacks. Its Clever Buoy is a near-shore shark detection system using state-of-the-art sonar and identification software to detect sharks and relay accurate, real-time data to the authorities responsible for beach safety.
Clever Buoy uses the latest generation of multi-beam imaging sonars which provide a real-time, high-frequency imaging solution. This high-tech sonar is combined with SharkTec, innovative shark-detection software and processing electronics.
Talking to E&T, company director Craig Anderson explains: “Clever Buoy uses multi-beam sonar, developed by TriTech in the UK, coupled with our pattern-recognition software. The basis of the software is a pattern-learning algorithm, very much like facial recognition software, but based on pattern-matching for the swim patterns of objects in the water.
“Once the system detects an object within range, it then interrogates its swim pattern to determine whether it’s a shark or not. Sharks have a unique swim pattern. Once it has a positive identification of a shark it autonomously implements a notification process through to authorities that are charged with the responsibility of public safety.”
With two successful pilot full-beach installations under its belt, one on the east coast at Bondi Beach and the other at Perth’s main city beach on the west coast, SMS also undertakes short-term deployments around sporting events such as the World Surf League, where the system’s advantages come into their own. The detection system is deployed beyond the surf zone where its multi-beam sonar transducers are mounted on the ocean floor where the detection software can scan for marine life.
As Anderson adds: “The advantage of the system is that there is nothing else that can really be deployed in a high-surf zone. Anything that’s a physical barrier does not withstand the high-energy environment of a surf beach. In that regard, we don’t really have a peer product; the closest thing we have are the old, physical barrier nets, but they can’t be deployed at the sort of beaches that our system has been designed for.”
If a shark is detected, the message is then instantly relayed to lifeguards on the beach with information about both the target and location, so that the alarm can be raised. Anderson comments: “The system needs the object within range for about four seconds for it to be able to interrogate its swim pattern - it’s basically instantaneous. From there it’s down to the time it takes to get the messaging out through the mobile phone network. We’re talking 10-15 seconds.”
And from a public perception point of view: Clever Buoy is a non-invasive technology. The sonar frequency it uses is in the magnitudes of thousands outside of the hearing range of any marine species and is, therefore, completely benign in its impact on marine life. In addition, it has none of the environmental or conservation issues surrounding by-catch, as Anderson says: “Physically there’s nothing there – it’s a virtual net rather than a physical net.”
Although rare, encounters with sharks will continue to occur as long as humans enter the water. The translation of scientific research and technological innovation into non-invasive shark deterrents offers a life-line to both: reducing the risks to ocean-goers, as well as protecting the marine life within it and furthering our understanding of the impressive Elasmobranchs.
Sharks in the water
Common to depths of 2,000m, sharks have a covering of dermal denticles, tiny flat V-shaped scales more like teeth than fish scales that make them super-efficient in the water, decreasing drag and turbulence and allowing them to swim faster and more quietly, preferably accompanied by a John Williams’ film score.
Their most infamous trademark is undoubtedly their numerous sets of sharp and pointy, replaceable teeth.
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