Do shark repellents actually work?

Mostly no — with one exception. In controlled testing on white sharks, only electrical deterrents (like the Ocean Guardian Freedom+ Surf) measurably changed shark behaviour. Magnetic bands, electrical leashes from other brands and 'shark-repelling' wax showed little to no effect. Even the best device reduces risk rather than removing it.

What is the best shark deterrent for surfers?

Based on the strongest independent study to date (Huveneers et al., 2018), electrical deterrents using the Shark Shield / Ocean Guardian technology performed best, cutting the share of baits taken by white sharks from 96% to 40% and pushing the sharks slightly further from the board. No device is foolproof.

Does the 'smell of death' shark repellent exist?

It's real science, not a finished product. Researchers have identified 'necromones' — chemical alarm signals released by decomposing shark tissue — that halted feeding in reef and blacknose sharks within a minute in field trials. But it hasn't been proven as a practical, wearable deterrent for surfers against large sharks like great whites.

What lowers my shark risk the most?

Your behaviour, not a gadget. Avoiding dawn and dusk, murky or bait-rich water, river mouths and seal colonies, and not surfing alone, does more to lower an already very low risk than any product currently on the market.

Do Shark Deterrents Actually Work? What the Science Says

The honest answer is: mostly no. Of all the shark deterrents a surfer can actually buy, only one type has solid evidence behind it — and even that one doesn't make you invulnerable. Everything else ranges from "might help a little" to "did nothing measurable in testing."

That's not the answer the marketing wants you to hear. But it's the one worth knowing before you paddle out trusting a bracelet.

Why nothing is foolproof

Sharks are extraordinary hunters. A great white can detect a single drop of blood in a swimming pool's worth of water, sense the faint electrical fields of a heartbeat through jelly-filled pores in its snout, and feel pressure changes from a struggling fish far away. You are trying to interrupt one of those senses with a small battery or a magnet. Sometimes it works. Often it doesn't.

So keep the framing right. A deterrent is a way to tilt already-tiny odds a little further in your favour. It is not a force field, and no honest company will tell you it is.

The one with real evidence: electrical deterrents

The most useful thing anyone has done on this question is a 2018 study out of South Australia. Researchers tested five personal deterrents on wild white sharks at the Neptune Islands — 297 trials, 44 different sharks, more than 1,400 passes at the bait. Real sharks, real ocean, measured properly.

One device stood out. The Ocean Guardian Freedom+ Surf, which uses the Shark Shield electrical-field technology, cut the share of baits taken from 96% down to 40%, and nudged the sharks a little further from the board. That's a meaningful reduction. It's also, tellingly, a long way from zero — four in ten sharks still took the bait.

Electrical deterrents work by overwhelming those electrical-sense organs at close range with a strong, unpleasant field. They're bulkier and pricier than a wristband, and the field only reaches so far. But if you want the option with the best current evidence, that's it.

The ones that mostly didn't

In the same study, the other four deterrents — an electrical leash from a different brand, two magnetic Sharkbanz products, and a "shark-repelling" surf wax — showed little to no measurable effect on white shark behaviour.

That doesn't make them useless to everyone. We've reviewed the Sharkbanz and rated it fairly, because for some people the calm it brings is worth the price on its own, and the magnetic effect has some support at very close range with curious, non-predatory sharks. Just be clear about what you're buying: peace of mind, not proven protection against a hunting great white.

The "smell of death" — real research, oversold

You may have read that scientists found a "smell of death" that sends sharks fleeing. There's genuine science under that headline, and it's fascinating.

Researchers have spent years chasing "necromones" — chemical alarm signals released when a shark's body decomposes. The old surfers' anecdote that sharks avoid a spot where one of their own has died turns out to have something to it. In field trials in the Bahamas, an extract made from putrefied shark tissue halted feeding in reef and blacknose sharks within about a minute.

That's a real result. But notice the gap. Those trials used aerosol canisters on reef and blacknose sharks, not a slow-release gel worn by a surfer, and not the big coastal species most of us actually worry about. It's a promising line of research. It is not, yet, a product proven to keep you safe. Anyone selling it as a finished surf solution is getting ahead of the evidence.

What actually helps

Here's the part that costs nothing and works better than any gadget: your own choices.

Avoid the risky windows. Dawn and dusk are feeding times. Murky water, river mouths after rain, and areas thick with bait fish or seals stack the deck against you.
Don't surf alone. More eyes, and help nearby if it's ever needed.
Leave the jewellery and bright contrast at home if it worries you, and get out of the water calmly if you see bait balls, seals acting spooked, or a fin.

None of this is glamorous. It's also, honestly, where nearly all of your safety actually comes from.

The bottom line

Shark bites are extraordinarily rare, and it's worth holding onto that. If you want a device, the electrical deterrents are the only category with strong evidence, and they lower risk rather than remove it. The magnetic bands may be worth it for your own peace of mind, as long as you know what they are. And the "smell of death"? Keep an eye on it. The science is real and the idea is clever — but it hasn't earned your trust in the lineup yet.

Surf smart, choose your conditions, and let the gadgets be a small bonus rather than the thing you're relying on.

Sources: Huveneers et al., "Effectiveness of five personal shark-bite deterrents for surfers," PeerJ, 2018; SharkDefense necromone research.