Captive sandbar sharks at the Virginia Institute of Marine Science stopped feeding and altered swimming patterns around metals with a positive electric charge, found a recent study by NOAA scientists.

"Individual sandbar sharks would generally not approach the metal ingots closer than about 24 inches, nor attack pieces of cutbait suspended within approximately 12 inches,” said Richard Brill, a research scientist at NOAA’s Northeast Fisheries Science Center.

The observed behavior may help fisheries biologists develop a strategy to reduce bycatch of sharks in longlining gear, given the rising concern of diminished shark populations worldwide.

Scientists believe the electrical field disrupts the shark’s electroreceptive system, which detects weak electric fields such as those generated by their prey. The next step would be to conduct field trials outside the lab.

Brill says juvenile sandbar sharks, Carcharhinus plumbeus, were used in the study because they are readily available in the estuaries along Virginia’s coast, do well in captivity, feed easily, and their constant forward motion makes it easy to measure changes in their swimming patterns.

“Our results were very promising but need further study,” Brill said. “The alloy we used, palladium neodymium, appears to be a good alternative to more expensive metals. It is also machinable and is reasonably resistant to corrosion in seawater.”

Read the complete article on the study at: http://www.nefsc.noaa.gov/press_release/2008/SciSpot/ss0806/ss0806.html