Will magnetic shark repellent hit shelves near you?

posted: 04/11/12
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Scientists have known for decades that the electrical currents gently pulsing through our planet's saltwater oceans — and the closely intertwined magnetic field originating from the Earth's core — affect marine life. The hows and whys, though, haven't always been clear.

Sharks, for example, seem to use electromagnetic fields in a couple of ways. Electroreception lets sharks track prey by following their electrical signals. Sharks may also use the Earth's magnetic field as a guidance system. Along with many other marine creatures, sharks seem to have an uncanny knack for remembering migration routes and performing other navigational feats.

This ability is where the idea of magnetic shark repellent comes in. Sharks are accustomed to the Earth's magnetic field, so it doesn't have a negative effect on them. But tossing a strong magnet into the water is something else entirely. Eric Stroud and Michael Herrmann discovered that sharks have an aversion to magnets when they accidentally plunked a rare-earth magnet into a shark pool in 2005.

Their discovery didn't immediately translate into an easy-to-use shark repellent for a couple of reasons. One is that the magnets affect different shark species to different degrees. A swimmer decked out in enough magnets to scare sharks away might also have a hard time staying afloat.

Stroud and Herrmann haven't given up, though. Through their company, Ocean Magnetics, they hope to create a viable shark repellent for use in commercial fishing. Such an invention could cut down on accidental shark deaths. Another potential use is anti-shark fencing for swimming areas. Eventually, magnets may help protect sharks and people alike.

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