SharkDefense is an internationally-recognized and award-winning research organization and think tank focused on shark bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...

 reduction. Its core research involves chemical and electrochemical shark repellent technologies. SharkDefense's repellent experiments have been featured extensively in the US and European media.

SharkDefense is notable as the discover of the permanent-magnetic and electrochemical repellent effects on sharks. These findings represent the first research efforts focused exclusively at selectively repelling sharks from commercial fishing gear without affecting the target catch. The repellent effect of electropositive metals on sharks was confirmed by the National Marine Fisheries Service, notably, Stoner and Kaimmer, (Fisheries Research Volume 92, Issues 2-3, August 2008, Pages 162-168, 2008), and studies completed by Brill et al. (2008) and Wang et al. (2008) also support the repellent effects. The preliminary research results on permanent magnetic shark repellents were reviewed, judged, and awarded the first place 2006 WWF SmartGear award. Recently (2008) the The Department of Primary Industries and Fisheries (DPI&F) and James Cook University (JCU), Australia confirmed that permanent (ferrite) magnets technology repel grey reef sharks, hammerheads, sharp-nosed sharks, blacktip sharks, the vulnerable sawfish and the critically endangered spear tooth shark.

In 2009, SharkDefense licensed its technologies to Repel Sharks LLC, which has commercialized aerosol, electropositive metal, and magnetic shark repellents. Magnetic shark repellent
Magnetic shark repellent
Magnetic shark repellents utilize permanent magnets, which exploit the sensitivity of the Ampullae of Lorenzini in sharks and rays . This organ is not found on bony fishes , therefore, this type of shark repellent is selective to sharks and rays...

s and Electropositive shark repellents are part of active research programs at SharkDefense.


SharkDefense was formed in September 2001 by Eric Stroud and Jean Stroud. Its research program began at the Oak Ridge Shark Laboratory with a search for trace chemical messengers present in decayed shark tissue. Previously (1943), Burden et al. from the Woods Hole Oceanographic Institution
Woods Hole Oceanographic Institution
The Woods Hole Oceanographic Institution is a private, nonprofit research and higher education facility dedicated to the study of all aspects of marine science and engineering and to the education of marine researchers. Established in 1930, it is the largest independent oceanographic research...

 (WHOI) had reported that decayed shark tissue was successful at halting feeding in captive dusky smoothound sharks (Mustelis canis). In the efforts to develop and test a chemical shark repellent package led by Dr. Harold Coolidge
Harold Jefferson Coolidge, Jr.
Harold Jefferson Coolidge, Jr. was an American zoologist and a founding director of the International Union for the Conservation of Nature as well as of the World Wildlife Fund ....

 of the Harvard Museum, the WHOI team selected ammonium acetate
Ammonium acetate
Ammonium acetate is a chemical compound with the formula CH3COONH4 . It is a white solid, which can be derived from the reaction of ammonia and acetic acid...

 as the active in the decomposing shark tissue, however, instrumental analysis by the Oak Ridge Shark Lab in 2002 failed to find ammonium acetate. It was hypothesized by SharkDefense that ammonium acetate was an approximation of the ammonium cation (based on the ammonia-like smell of the shark tissue or a urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....

Urease is an enzyme that catalyzes the hydrolysis of urea into carbon dioxide and ammonia. The reaction occurs as follows:In 1926, James Sumner showed that urease is a protein. Urease is found in bacteria, yeast, and several higher plants. The structure of urease was first solved by P.A...

 reaction), and the acetate conjugate base (based on the acetic acid
Acetic acid
Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...

 which WHOI had already found to have repellent properties). After 2002, many new compounds were found and catalogued by SharkDefense, who maintains a repellent compound database.


1. Apr. 15, 2003 – First successful field test of a semiochemical shark repellent, Triangle Rocks, South Bimini, Bahamas

2. May 2004 – A gustatory shark repellent (“5ISO”) is isolated and successfully tested

3. Nov. 2004 – Accidental discovery of the repellent effects of a rare-earth magnet is made at the Oak Ridge Shark Lab

4. Jul 12, 2005 – Testing at Achotines, Panama on captive yellowfin tuna
Yellowfin tuna
The yellowfin tuna is a species of tuna found in pelagic waters of tropical and subtropical oceans worldwide.Yellowfin is often marketed as ahi, from its Hawaiian name ahi although the name ahi in Hawaiian also refers to the closely related bigeye tuna. The species name, albacares can lead to...

 (T. albacares) confirms that both semiochemical mixtures and the gustation compound are selective shark repellents and do not repel a commercially-valuable fish species.

5. Sep. 15, 2005 - A 0.1ppm solution of a synthetic shark repellent compound terminates tonic immobility
Tonic immobility
Apparent death, colloquially known as playing dead or playing possum, is an antipredator behavior observed in a wide range of animals in which they take on the appearance of being dead to an observer...

 in juvenile lemon shark
Lemon shark
The lemon shark, Negaprion brevirostris, is a shark in the family Carcharhinidae, that can grow to long. It is known as the lemon shark because, at certain depths, light interacting with the local seawater can give this shark a tanned and yellow pitted appearance, much like the surface of a...

s (N. brevirostris).

6. Nov. 16, 2005 – Chemical repellents are successfully incorporated into a time-release gel matrix, providing more than 4 hours of protection time.

7. May 1, 2006 – Accidental discovery is made using an electropositive metal
Electropositive metal
Electropositive metals are a new class of shark repellent materials that produce a measurable voltage when immersed in an electrolyte such as seawater. The voltages produced are as high as 1.75 VDC in seawater. It is hypothesized that this voltage overwhelms the ampullary organ in sharks,...

as an experimental control at South Bimini, Bahamas.

8. May 11, 2006 – SharkDefense is the grand prize winner of the 2006 WWF Smart Gear competition for its proposal on permanent magnet shark repellents.

9. Aug. 31, 2007 - Fish attractant qualities of the gustation compound are confirmed.

10. Jun. 2007 – SMART Hook technology developed.

Current members

2001 – Present. Mr. Eric M. Stroud (Seton Hall University, Ph.D. candidate) was the co-founder of SharkDefense and led the initial research to identify chemical repellent actives. He is currently the managing partner and is researching chemical signals and necromones as part of his PhD.

2006 – Present. Dr. Patrick H. Rice (University of Miami, RSMAS), partner, joined the SharkDefense team in 2005 while researching the repellent effects of permanent magnets. He is presently the director of marine sciences at Florida Keys Community College and is senior marine biogist with SharkDefense.

2006 – Present. Mr. Craig P. O’Connell (Coastal Carolina University, Ph.D. student), partner, joined the SharkDefense team as marine biologist in 2006 while working on a contract shark repellent-sunscreen project at South Bimini, Bahamas. He is currently researching magnetoreception as a shark bycatch mechanism for his Ph.D.

2010 - Present. Mr. Conrad Eskelinen (DiveBum Studios), partner, joined the SharkDefense team as creative director in 2010.

2003 – Present. Dr. Samuel H. Gruber (University of Miami, RSMAS, professor emeritus), consultant, has assisted and supervised many SharkDefense repellent trials at the Bimini Biological Field Station.

2003 - Present. Mr. Grant T. Johnson (South Bimini, Bahamas), consultant, providing field and testing support.

2004 – Present. Ms. Katie Grudecki (South Bimini, Bahamas), consultant, providing field and testing support.

2004 – 2010. Mr. Sean Williams (Bimini Biological Field Station), consultant, providing field testing support.
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