SSS 2008-05-02（在线收听）

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This is Scientific American's 60-Second Science. I'm Cynthia Graber. This'll just take a minute.

Sharks inspire fear as great predators, but their numbers are declining around the world. One way sharks occasionally meet their doom is by getting tangled up in long-line fishing gear. And they can eat the bait set out for the desired fish which makes fishing less efficient and more expensive. But scientists at the National Oceanic and Atmospheric Administration recently noticed something unusual. They reported their findings at a workshop on shark deterrence. Some metals react with sea water to create electrical field. And the researchers saw that captive sharks were avoiding areas around one such metal--palladium neodymium. So they thought why not use this finding to help save sharks in the wild and protect the fishing industry? Sharks are sensitive to electrical fields which they use both to find food and to help them navigate through the ocean. It's believed that the electrical fields created by palladium neodymium make sharks back off because they somehow overload the animals' sensory systems. Researchers say the next step is to test whether small ingots of metal in seawater consistently repel animals in the lab. If so, they would then incorporate the metal into shark-repelling fishing lines.

 Thanks for the minute. For Scientific American's 60-Second Science, I'm Cynthia Graber.