Rare Earth elements (elements 57-71 plus 21 and 39) have been found to repel sharks. The reason appears to be that they create an electrical current with the shark’s skin, effectively given the marvels of evolution a shock when they get too close. One study found that when the metals were used in certain types of commercial deep sea fishing, incidental (and unwanted) shark captures dropped by about 1/3.
(Also, these elements are called “rare Earth” not because they are rare but rather because they are notoriously difficult to tease away from other substances.)
Filed under: Misc | Tagged: Fun fact of the day, Rare Earth elements |
For the Sake of Science 
Hmm. I quite like this Fun Fact series of posts, but I am also both skeptical and curious. Could you post citations so I could learn more?
I saw this on a recent NOVA episode: http://www.pbs.org/wgbh/nova/physics/hunting-elements.html
What I forgot was that it was first found that magnets repel sharks (one or more of the rare Earth elements are also magnetic). The problem is that when metal hooks are magnetized, they tend to attract each. Mistaken shark catches go down, but so does the overall haul of wanted fish. Obviously. One solution was to try other rare Earth elements.
This link verifies the magnetic aspect of what I’ve said: http://www.pbs.org/wgbh/nova/nature/magnetic-fish-hooks-save-sharks.html
This link talks about two rare Earth metals (if I recall correctly, it is neodymium that is magnetic and it’s present in a ton of stuff we use every day; I don’t know if the other one is magnetic).
Thank you! :D