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Dr. Peter Bushnell catches a juvenile sandbar shark off the Virginia coast. Credit: Stuart SchroftWhen fishermen in the northeast go after swordfish and tuna they sometime hook blue sharks by accident ... a fish they end up throwing back. Now government scientists are researching a way to reduce the number of sharks that are inadvertently caught.

Scientists have known for a long time that some shark species are sensitive to electrical fields. Dr Richard Brill of the National Marine Fisheries Service say certain metals, known as rare earth metals which are byproducts of iron ore mining, will generate an electrical field in sea water. Brill wanted to find out whether sharks would be repelled if they were exposed to these metals in the ocean. He tested his idea on captive sand bar sharks and found they swam away.

“They react quite violently to the presence of this metal and we’re not sure but we’re fairly positive its due to the electric field that the metal creates when it reacts with sea water.”

Brill’s goal is to figure out if the metal could help fishermen working in the ocean to repel sharks. Brill says sometimes people don’t understand his research. He says they want to know if it will protect humans from sharks.

Swimming pattern of a sandbar shark in the presence of three bars of palladium neodymium suspended in a tank: Photo Credit: Leonie Smith, Bangor University, Wales“No that’s not the idea. We don’t need protection from them. They need protection from us. And that what this is to do.”

Populations of large predator sharks in the Atlantic are experiencing a serious decline, not only because they’ve been caught by accident, but because fishermen have targeted them for the medicinal properties of their fins.