How to repel sharks
Can electrical fields help keep these ocean predators at bay?
Sharks have gained the reputation of being cold-blooded killers, weaving their way through the waves on the hunt for their next human meal. It’s a stereotype sharks can’t shake, and one not actually substantiated by science. In 2019 it was reported that there were 64 unprovoked attacks on humans by sharks worldwide, with a further 41 cases occurring when the shark was provoked, such as removing fishing hooks or when a swimmer attempts to feed or touch them.
Nevertheless, sharks do pose a threat to human marine activities such as diving and fishing, and so tech companies such as Ocean Guardian have come up with a way to use sharks’ own biology against them to ward them away. Along with many other animal species, these giant fish have the ability to detect electrical signals emitted through the water – for example from the activity of other fish for the purpose of hunting. The discovery of this built-in electrical receiver created an opportunity to build devices that can disrupt this biological ability and ultimately ward off any nearby sharks, known as shark repellents. Strung from boats or strapped to the body or board of a surfer, these portable devices steer away sharks by emitting electrical signals that disrupt their internal receiver. But how effective are they?
Testing the efficiency of shark repellent technology isn’t easy to do, and some members of the scientific community question its effectiveness due to the lack of studies carried out with human subjects, which is an understandable gap in the research. However, some studies that have used these devices in isolation – without the distracting thrashing bodies of ocean swimmers – have shown a surprising ability to keep sharks at bay. One study found that when using one of Ocean Guardian’s shark shield gadgets, active devices deterred one-third of sharks when compared to an inactive device at close range. Although the science behind the devices may suggest some success, like most animals sharks can be unpredictable and don’t always follow the rules of science. If you’re out for a surf with shark repellent strapped to your leg and a big white swims towards you, don’t rely solely on electricity to save the day.