|
Electropositive metals (EPMs) are a new class of shark repellent materials that produce a voltage when immersed in seawater. The
voltages produced are as high as 1.75 VDC. It is hypothesized that this voltage overwhelms with ampullary organ in sharks, producing a repellent action. Since bony fish lack the ampullary organ, the repellent is
selective to sharks and rays. The process is electrochemical, meaning, no power input in the form of batteries or line power is required. As chemical "work" is being done, the metal is given up in the form of
corrosion. Depending of the alloy or metal utilized and their thickness, the electropositive repellent effect lasts up to 48 hours. The reaction of the electropositive metal in seawater produces hydrogen gas bubbles
and an insoluble nontoxic hydroxide as a precipitate which settles downward in the water column. The precipitate is inert for repellent activity.Reseachers at SharkDefense Technologies LLC discovered the
shark-repelling effects of electropositive metals in seawater on 01-May-2006 at South Bimini, Bahamas. Since that time, our research efforts have been focused on quantifying behavioral responses to various pure
metals and alloys, understanding the electrochemical and corrosion processes involved, and improving gear design with respect to incorporating these metals onto circle hooks. Initial repellent findings were
presented by SharkDefense at the
2006 Sea Turtle and Pelagic Fish Sensory Physiology Workshop
, the 2007 American Elasmobranch Society (AES) / Joint Meeting of Ichthyologists and Herpetologists in St. Louis, MO, and the Shark Deterrent and Incidental Capture Workshop at the New England Aquarium, April 11, 2008..
As of 2007, SharkDefense is collaborating with NOAA, NMFS, and other fisheries scientists to validate and promote the use of these metals as a shark bycatch reduction technology. Please refer to the publication
"Reducing elasmobranch bycatch: Laboratory investigation of rare earth metal and magnetic deterrents with sping dogfish and Pacific halibut"
. Stoner, Allan W. and Kaimmer, Stephen M. Fisheries Research, 2008.Since electropositive metal represent the cutting edge in
shark repellent research, much remains to be studied and learned. Species-specific behavioral differences, particularly for dogfish, have already been made. These observations will provide valuable insight to future
shark repellent research. Below, please find a summary of the testing performed with electropositive metals (successes, failures, publications, and press) to date, which will be updated frequently. |