Shark-repellent metal alloys are used in commercial, recreational, and artisinal fisheries to reduce the amount of unintended shark catch (shark bycatch). When tuna and swordfish are targeted, sharks are also captured and present handling problems and damage to gear. More hooks occupied by sharks means less hooks available for the targeted species. The metal alloy is placed as close as possible to the bait. Since the metal alloy is specific to the electrical sense in sharks, bony fish are not repelled, thus, the metal alloys are a shark bycatch reduction device.

Shark-repellent alloys, or 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 relative to a shark skin electrode in a seawater electrolyte at pH 8.1 and standard conditions. 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 lasts up to 48 hours continously submerged in seawater.

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. These metals are constituents of natural seawater. An extensive literature search revealed no toxicity issues, and the metals used are not cited as toxic/poisonous or restricted compounds.

 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 following publications: "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, AND,  Brill, R., Bushnell, P., Smith, L., Speaks, C., Sundaram, R., Stroud, E., Wang,  J. 2009. The repulsive and feeding deterrent effects of electropositive metals on juvenile sandbar sharks (Carcharhinus plumbeus). Fisheries Bulletin. FB-3298, AND, "Field investigation of rare-earth metal as a deterrent to spiny dogfish in the Pacific halibut fishery", Kaimmer, Stephen and Stoner, Allan W. Fisheries Research Volume 94, Issue 1, October 2008, Pages 43-47. 

Since electropositive metals represent the latest technology 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.

SAMPLE PHOTO

Hemispherical shark repellent alloy (approx. 100 grams)

SAMPLE VIDEOS

(M1V MPEG) Bat ray turning 180 degrees near metal alloy (suspended at center). Courtesy Allan Stoner, NMFS

(M1V MPEG) Broadnose Seven-Gill shark and Leopard shar turning 90 degrees near metal alloy (suspended at center). Courtesy Allan Stoner, NMFS

(WMV) Galapagos sharks avoiding bait near metal alloy - Courtesy John Wang, NOAA

 (WMV) Galapagos shark eating bait - NO ALLOY PRESENT - NOT PROTECTED - Courtesy John Wang, NOAA

(M1V MPEG) Leopard shark and sping dogfish turning away from metal alloy (suspended at center). Courtesy Allan Stoner, NMFS

WMV) Immobilized lemon shark responding to the metal alloy  AND ANOTHER (WMV) Immobilized lemon shark responding to the metal alloy

Immobilized nurse shark responding to the metal alloy - Blinder removes visual clue

(WMV) Immobilized nurse shark - Control test with moving hand, NO ALLOY PRESENT

Species Responding Favorably

 

Sandbar Shark    (C. plumbeus)

Brill et al, 2008 (NMFS, VIMS)

Wang, Naughton, Swimmer (NMFS, Kewalo)

 

Pacific Spiny Dogfish             (S. acanthias)

Stoner & Kaiimer, 2008

 

Galapagos Shark   (C. galapagensis)

Wang, Naughton, Swimmer (NMFS, Kewalo)

 

Juv. Lemon Shark   (N. brevirostris)

SharkDefense (South Bimini)

Broadnose Seven-Gill Shark

(N. cepidianus)

Stoner, 2008 - Oregon Aquarium

Bat Ray (M. californica)

Stoner, 2008 - Oregon Aquarium

Leopard Shark (T. semifasciata)

Stoner, 2008 - Oregon Aquarium

 

Juv. Nurse Shark (G. cirratum)

SharkDefense (South Bimini)

Species Not Responsive

 

Atlantic Spiny Dogfish                ( S. acanthias)

Tallack, 2008 GMRI

Mandelman, 2008 (NEAQ)

 

Dusky smoothhound      (M. canis)

Mandelman, 2008 (NEAQ)

 

Brown smoothhound      (M. henlei)

Wang, 2007 (Baja)

PRESS ARTICLES ON EPMs

Shark repellent is a matter of life and death - for sharks

Virginian-Pilot. Joanne Kimberlin, August 2, 2008

 

Reducing Elasmobranch Bycatch on Longline Gear: Laboratory and Field Studies With Rare-Earth Metal Deterrents

Newport Laboratory: Fisheries Behavioral Ecology Program - Dr. Allan Stoner  | PDF

 

Sharks Repelled by Metal That Creates Electric Field

Helen Scales, May 1, 2008

Metals that generate electric fields may keep sharks away

Dawn Stover, June 7, 2008

Ichthyology at the Florida Museum of Natural History

Electric Fields Could Repel Sharks

Clara Moskowitz, May 6, 2008

Commercial Fisheries News

Can mischmetal stave off dogfish hordes?

Ken La Valley - Sept. 2007

Experimental Fishing Gear Projects

NEAQ, 2008 | PDF

Can Certain Metals Repel Sharks From Fishing Gear?

April 24, 2008

Commercial Fisheries News

Mischmetal not feasible as dogfish deterrent

Janice M. Plante, May 2008

PUBLICATIONS AND ABSTRACTS

PAPER: Brill, R., Bushnell, P., Smith, L., Speaks, C., Sundaram, R., Stroud, E., Wang,  J. 2009. The repulsive and feeding deterrent effects of electropositive metals on juvenile sandbar sharks (Carcharhinus plumbeus). Fisheries Bulletin. FB-3298.

PAPER: "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.

PAPER: "Field investigation of rare-earth metal as a deterrent to spiny dogfish in the Pacific halibut fishery", Kaimmer, Stephen and Stoner, Allan W. Fisheries Research Volume 94, Issue 1, October 2008, Pages 43-47.

PAPER: Tallack, M.S.L & J. Mandelman, (in prep). Do rare earth metals deter spiny dogfish? A feasibility study on the use of Mischmetals to reduce dogfish catches in hook and lobster gear in Gulf of Maine.

TECH MEMO: Swimmer, Y., J.H. Wang, and L. McNaughton. 2008. Shark deterrent and incidental capture workshop, April 10-11, 2008. U.S. Dep. Commer., NOAA Tech Memo., NOAA-TM-NMFS-PIFSC-16. 72p.

AES 2008 Abstract: The Shifting Baseline of Threshold Feeding Responses to Electropositive Metal Deterrents in Two Species of Dogfish. John Mandelman, Michael Stratton, Michael Tlusty, Shelly Tallack, Tom Fisher, Cheryl Harary, Nils Wernerfelt

AES 2008 Abstract: Do Rare Earth Metals Deter Spiny Dogfish? A Feasibility Study on the Use of Mischmetal to Reduce Dogfish Catches in Hook and Lobster Gear in Gulf Of Maine. Shelly Tallack, John Mandelman

AES 2008 Abstract: Advances in Shark Repellent Research Using Highly Electropositive Metals. Eric Stroud, Patrick Rice, Craig O'Connell, Samuel Gruber

AES 2007 Abstract: The Use of Highly Electropositive Metals as Shark Repellents. Eric Stroud, Patrick Rice, Craig O'Connell, Samuel Gruber