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Scientists Have Developed a Shark-Repelling Device For Your Surfboard

Thank you, science.

FIONA MACDONALD
14 SEP 2015
 

Researchers have developed an electronic device that you can attach to your surfboard or wear while swimming to help deter sharks. The aim is to harmlessly mess with the animals' electroreceptive system, and studies so far have shown that they can prevent more than 90 percent of shark encounters.

Before you all rush off to buy one, let's get one thing straight: shark attacks are incredibly rare, with on average just 75 being reported worldwide every year. That means you have on average a roughly one in 11.5 million chance of being attacked by a shark (and if you rarely swim more than 25 metres out from the beach, it's even lower than that) - which is far less than your risk of dying from home repairs or, say, a bicycle-related injury.

 

But despite all of us very sensible people knowing that we're probably not going to be attacked by a shark in our lifetimes, we can't help but be terrified by the idea of it. Which is why scientists have been working for decades on humane ways to repel the animals.

Several countries, including Australia, have experimented with culling sharks in the past to see if that would help to reduce shark attacks. But not only is the practice inhumane and bad for the environment - we already wipe out around 100 million of these crucial apex predators every year for their fins - it actually doesn't do anything to reduce attacks.

So researchers have been looking for ways we can use the animals' biology to keep them away without having to harm them. What's unique about sharks is that they have two extra senses that we don't have that allow them to hunt underwater - the ability to sense both vibrations and electrical fields through a network of sensors in their heads.

It's this second sense that the shark repelling devices target, by sending out electromagnetic pulses that aim to make a shark uncomfortable and confused so it moves away from the area.

There are a couple of these devices on the market at the moment, but the one that's been the most widely and independently tested is the Shark Shield, which was developed in Western Australia. The device is made up of two electrodes that emit a 3D electronic field once they're submerged in water.

The electronic field causes sharks to experience muscle spasms in their snouts the closer they get to the device. Researchers have tested this on reef and great white sharks in the wild using bait, and found that 100 percent of sharks ate bait that was left unprotected, while only 10 percent took it if it was protected by the Shark Shield.

Scientists at the University of Western Australia are now fine-tuning the frequency of the device in the lab, using embryonic bamboo sharks, which mature in an egg case outside their mother's body. This allows scientists to test which frequencies affect the sharks the most - they've even managed to find one that makes sharks play dead. You can see some tests in the video below:  

There are a few different models of Shark Shield - all of which retail upwards of A$600 - including one that attaches to the bottom of a surfboard and one that can be worn around a swimmer's ankle. But despite the promising results so far, it's hard to know how effective these types of devices will be in the long run.

"The natural reaction of sharks, when they first detect something they aren't familiar with - such as one of these electrical pulses - is to turn away," shark researcher Ryan Kempster from the University of Western Australia's Ocean Institute told Simon White from The Sydney Morning Herald back in 2012. "But we don't know yet whether that reaction stays the same for the fourth time or the fifth time."

The other issue is that sharks can only detect electric fields from around 50 cm away, which means that sharks can still get pretty close before being repelled by the device.

Still, it's promising research that will hopefully help people feel safe in the water again - without having to kill or harm a crucial part of our ocean ecosystems.

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