Shark Sense (Part 2): Electronic Shark Deterrents

Electroreception – The Weakest Link?

Sharks have an arsenal of senses to help them detect and zone in on their prey, and as discussed in part 1 of this article, ocean users are advised not to pique the interest of a shark by stimulating any of these senses. However, scientists have discovered an area where sharks are vulnerable, and that it is in fact possible to exploit one sensory system – electroreception – to our advantage, without harming the shark.

How Does an Electronic Shark Deterrent Work?

An electronic anti-shark device, such as Shark Shield, deters sharks by emitting an electronic pulse that discomforts an approaching shark. The Shark Shield consists of two electrodes that produce an electric field, which surrounds the diver when both electrodes are simultaneously placed under water. These electronic pulses interfere with the shark's Ampullae of Lorenzini -- the highly sensitive sensory organs on the shark's snout that act as electrical receptors, which aid in detecting electrical fields produced by their prey.

When a shark approaches a diver wearing a Shark Shield, the electronic field produced by the device causes muscular spasms in the shark. This painful sensation causes the shark to change course and move away from the source of the electronic pulses (i.e. the diver wearing the device), in effect acting as a shark repellent that protects the diver from any potential threat.

Studies on Electronic Shark Deterrent

A number of scientific studies have been conducted on the Shark Shield electronic shark deterrent that support the effectiveness of this device as a shark repellent when the device is activated. In an initial study assessing the effectiveness of an electronic shark deterrent (conducted on the pioneer model – SharkPOD – the predecessor of the Shark Shield) scientists found that when the device was activated, the likelihood of a shark taking bait was reduced by 80% (Smit & Peddemors, 2003).

A recent independent study was conducted to assess the effectiveness of the Shark Shield FREEDOM7 electronic shark deterrent on white sharks in the wild, using field experiments that tested white shark responses to both a static bait (natural prey) and a dynamically towed seal decoy. Researchers found that, on average, when the device was activated, sharks did not approach as closely, and took twice as long to take a static bait, while the incidence of a predatory strike on a dynamically towed seal decoy was reduced (Huveneers et al, 2012). The study found that when activated, an electronic shark deterrent affected the behaviour of sharks within a two-meter radius of the device. The study also confirmed that sharks were not initially attracted to the device before being repelled.

Shark Shield Product Options for Divers

Shark Shield offers two products for divers: the FREEDOM7 and the SCUBA7. The FREEMDOM7 comprises an electronic anti-shark device that is housed within a neoprene pocket, which attaches securely to the ankle with a Velcro ankle-strap. The antenna from which the electronic pulses are emitted consists of a 2.2-meter long cable that extends from the ankle-strap, trailing behind the diver/swimmer as he/she swims along, surrounding the user with an electronic field that effectively repels sharks. The SCUBA7 model has an electrode that attaches directly onto a SCUBA tank.

The Shark Shield FREEDOM7 is a versatile electronic shark repellent that can be used by divers and other ocean users such as bathers, body boarders and kayakers to allow them to safely enjoy a variety of ocean activities with peace of mind. Its versatility makes it the ideal choice if you enjoy snorkelling as well as SCUBA diving, or if you partake in various other ocean activities. The Shark Shield SCUBA7 is designed to be used exclusively with SCUBA tanks, and thus can only be used when SCUBA diving and not during other ocean activities.

Ocean users can use a Shark Shield anti-shark device for up to 7 hours before it will require recharging. These devices are fitted with both audible and visual alerts that flash or sound when the battery needs to be recharged. For ocean die-hards who wish to spend extended hours on or in the ocean, spare battery packs can be purchased to allow the user to swap a depleted battery for one that is fully charged and return safely to the water while the first one is recharging.

If you dive in waters that are frequented by dangerous sharks, a Shark Shield electronic shark deterrent may be a gadget worth adding to your dive gear -- it could save your life.

Back to Part 1