There are more than 465 species of sharks roaming the world’s oceans and most of them are considered an apex predator (Get it?) at the top of their food chains. Most shark species subsist on a diet consisting of fish, crustaceans, mollusks, plankton, and other marine mammals. This can become a problem for fishermen who sometimes find enormous sharks trapped in their nets while trying to sneak a bite of the day’s catches. While the sharks can typically be removed from the traps unharmed, it can be a really difficult process. How can commercial fishermen keep sharks from getting caught in their nets?

Repelling Sharks with Magnets

According to a study done by researchers at the University of Newcastle, sharks can be repelled from fishing nets using magnets. Tiny magnets placed near the entrance of the traps created a magnetic field around the opening. In over 1,000 traps set, it was discovered that those with magnets on them caught 30% fewer sharks than those without magnets. Plus, because those traps had fewer sharks attracted to them, the traps caught more fish - a serious bonus for the fishermen.

Why Do Magnets Repel Sharks?

American chemist Eric Stroud tasked himself with finding a working repellant for sharks after a summer where “It seemed like everyone that stepped in the ocean in Florida was getting attacked by a shark.” He set up small pools in his basement filled with water and nurse sharks. He observed how the sharks behaved, ate, and interacted until one day when he accidentally dropped a magnet near one of the pools. The nurse sharks darted away and avoided the area near the magnets. Sharks have very handy electrical sensors called ampullae of Lorenzini. These electroreceptors appear as small pores on the nose of a shark. Scientists believe that sharks use these sensors to not only navigate using the earth’s magnetic field but also to sense their prey’s heartbeat. It’s possible these spinning magnets disrupt their senses and disorient them. Stroud’s experiment did not seem to affect other species such as tuna, swordfish, and crabs, but many fish do have a magnetic orientation behavior. It could potentially affect sea turtles in the same way as sharks since they utilize the earth’s magnetic field to navigate back to the beach where they were hatched to lay their own eggs. We’re glad that the fishermen found a safe way of repelling the sharks from their catches and we’re extra glad it was a magnetic solution! What other uses like this do you think magnets can be used for? Keep an eye on our News & How-To’s section for more magnet-related news and fun DIY’s.