Shark deterrence devices that Sydney surfers and divers swear by

In the early morning hours, the sun had just risen over Dee Why when a suspicious bull shark attacked Alex Preston’s legs.

He had already surfed a handful of waves at his local break when stunning beachcam footage captured the shark lunging and leaping at Preston, who curled up onto a wave and ducked out of danger as his dorsal fin broke the surface.

This was the last wave Preston caught that morning. However, when he returned home, he realized how close the shark had come when his wife, while reviewing the footage, pointed out that he had narrowly escaped.

The encounter occurred weeks after an 11-year-old boy was knocked into the water by a shark on the same break and across the headland from where Preston’s “great friend” Mercury Psillakis was fatally injured at Long Reef in September.

He thinks there’s a good chance of a near-miss in mid-February. But he was also grateful for the shark-deterrent safety tape he wore, which he likened to a “bike helmet” strapped to his ankle.

“I had a crack on my legs…it was a pretty casual interaction until I saw the video and saw the full picture,” Preston said.

“I had shark tape on my feet and I assume that kept the shark away.”

Preston is among a growing number of Sydney surfers wearing deterrent patches following horrific shark attacks off the NSW coastline in the past six months.

The bands worn around wrists and ankles create an electromagnetic field that irritates the electroreceptors that sharks use to navigate the oceans and track their prey. The effect on the shark was compared to shining a bright light on a person in a dark room.

Sharks are able to resist unpleasant sensations, and the effectiveness of the device depends on a variety of environmental and situational factors. This includes the number of sharks in the water near the person and how fast the device is moving.

Tests show that sharks exhibit avoidance behavior between 0.5 and 2 metres. Results from Western Australia’s Department of Primary Industries and Regional Development in 2021 showed sharks “suddenly” changed direction when near the device.

The tapes are among a variety of shark deterrents on the market, which also include camouflaging wetsuits and surfboards designed to hide surfers in the water column.

These are important to diver Nick Rendall, who runs an underwater boat cleaning and maintenance business in Sydney Harbour. He and his staff wear the patches “religiously” as they dive into murky, brackish waters with limited visibility that are often known to attract sharks.

“If you combine something like a shark group with a little bit more information about shark behavior, you can really make sure that all these shark attacks that are happening won’t happen,” Rendall said.

“The science behind it makes sense, and knowing it also means I have protection. It definitely provides nice peace of mind.”

Holly Cummins wears two of the patches while surfing after being attacked by an almost two-metre bull shark in the waters off Killalea Regional Park on the South Coast last month.

“I didn’t see it coming; a surf buddy of mine witnessed it from behind, said it came up behind my board, exploded and swung around a few times before disappearing,” Cummins said.

“If I hadn’t put the bench on it would have been a very different outcome.”

Nathan Garrison, co-founder of deterrent groups Sharkbanz, reported a 30 per cent increase in sales from Australia in January, when 12-year-old Nico Antic was killed by a shark in Sydney Harbor and South Coast musician Andre de Ruyter had to have his leg amputated after being injured in Manly.

Garrison acknowledged it’s hard to know how much of an increase there is due to attacks, but said demand is certainly higher as ocean users try to protect themselves.

“Deterrents could be part of this [response]“But understanding what triggers additional shark activity and how to avoid high-risk areas is also extremely important,” he said. “These are safety devices and cannot completely eliminate risk.”

University of NSW Professor Dewei Chu said it was a good idea because the devices “disrupt the shark’s navigation, causing it to get lost”.

Surf lifeguard and surfer clubs are among the organizations showing new interest in deterrence groups, Garrison said.

The results show the bands are most effective against bull sharks, the species suspected of being behind four attacks within 48 hours off the NSW coast in January, including on Antic and de Ruyter.

Chu favored tapes over shark nets (responsible for more than 200 marine animal deaths in the summer of 2024-25) and recommended combining them with other safety strategies in the water.

“So we could have very good protection for people swimming or diving… I think that’s the future.”

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