Can certain metals repel sharks from fishing gear?

The sandbar shark, Carcharhinus plumbeus, is one of the largest coastal sharks in the world and can reach lengths of eight feet and weigh as much as 200 pounds. Sandbar sharks are usually found in shallow coastal waters including bays and estuaries in tropical and temperate waters around the world. In the western Atlantic Ocean they range from Massachusetts to Brazil, with the waters of the lower Chesapeake Bay considered a major nursery ground. Humans are their main predator.

“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. How long the metal will last before corroding and how long it will repel sharks in the field, however, needs to be determined.”

The lab experiments were conducted at the Virginia Institute of Marine Science using juvenile sand sharks up to five years old caught in surrounding waters and brought to an outdoor holding tank.

In addition to Brill, the study included scientists and students from Indiana University, Bangor University in Wales, Hampton University in Virginia, the University of Hawaii, and the research firm Shark Defense LLC of Oak Ridge, NJ, which develops shark repellents. Principal funding was provided by the Pacific Islands Fisheries Science Center of NOAA’s National Marine Fisheries Service in Honolulu, with logistical support from the VIMS Eastern Shore Laboratory.

This study by Brill and colleagues is among the first to rigorously test the use of rare earth materials on repelling elasmobranchs, and supports a recent study using metal alloys to repel spiny dogfish conducted by NOAA researchers in Oregon.

Results of the sandbar shark study were presented at a NOAA-sponsored shark deterrent workshop in Boston earlier this month.

NOAA Fisheries Service is dedicated to protecting and preserving our nation’s living marine resources and their habitat through scientific research, management and enforcement. NOAA Fisheries Service provides effective stewardship of these resources for the benefit of the nation, supporting coastal communities that depend upon them, and helping to provide safe and healthy seafood to consumers and recreational opportunities for the American public.

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