Shark Repellent – does it really work?

Unfortunately, fatalities caused by shark attack have been on the rise over the past decade. But it still hasn’t stopped us enjoying the deep blue sea. On the contrary, kite surfing, stand up paddle boarding, swimming and surfing remain much-loved watersports in Australia. Not to mention the many Aussies who explore the beautiful marine life via scuba or snorkel.

For most people, the joy of being in the ocean outweighs the potential risk of meeting a shark. But wouldn’t it be nice to reduce the risk, just a little?

That’s where shark repellent comes in.

What is shark repellent?

‘Shark repellent’ is a general term, which refers to any method used to deter sharks from a particular area. There are many different kinds of shark repellents, including:

  • Magnetic shark repellent
  • Electro-positive shark repellent
  • Electrical shark repellent
  • Semiochemicals (AKA chemical substances)

Do they really work?

Researchers from Flinders University in Adelaide and the South Australian Research and Development Institute (SARDI) looked into the effectiveness of electronic shark shields.

Tests were conducted off Neptune Island, South Australia and off the coast of South Africa. They used separate methods to collect their research.

Tuna Bait & Decoy Seals

  • Researchers in South Australia towed a tuna bait and burley off the back of a boat.
  • In South Africa, a decoy seal was the lure of choice.
  • Both methods tested a Shark Shield Freedom 7 device, one of the more popular electronic shark deterrents on the market.

How it works

  • The submersible Shark Shield 7 is strapped to the user’s ankle with a 2.2 metre braided antenna. The antenna emits the electronic pulse.
  • The electronic pulse produces an elliptical field, which agitates electro-receptors in the nose of the shark. (These receptors help a shark hunt food, as it can locate injured animals by sensing irregular electromagnetic pulses.)
  • The shark doesn’t like this feeling of the electronic pulse, so, it leaves the area.

What happened?

Here’s what they discovered:

  • Results varied from shark to shark.
  • Results varied between testing methods too.
  • In South Africa (where the seal decoy was used), researchers noticed 16 breaches and 27 interactions with the seal out of a total of 189 trials.
  • When they turned on the shield, researchers noticed that sharks visibly aborted their attacks. Not one surface breach was observed when the shield was on.
  • Off Neptune Island, researchers found that overall, sharks did not respond uniformly to the activated shield. Out of 116 static trials some sharks swum within 2-metres of the shield, while others took the bait, even when it was turned on.

Does it work?

It’s important to note that the experiments in question focused on how sharks reacted to the shield. They weren’t testing the shield in human to shark interactions.

In any case, the findings do shed light on whether electronic shark shields really do act as a deterrent.

Researchers confirmed that:

  • Great whites took twice as long to capture static bait when the shield was on. (On average.) This suggests that sharks do hesitate when the pulse is activated.
  • The shield they tested didn’t repel or deter sharks in every case.
  • And it didn’t repel or deter every individual shark either.
  • It’s best not to rely on a shield for protection, if you’re planning on swimming with sharks.

For more insights into the marine world, head to our blog. Or call our marine specialists about insuring your vessel.