Chemical Shark Repellent Research and Development
Eric M. Stroud, Michael M. Herrmann & Dr. Samuel H. Gruber
Eric M. Stroud and Michael M. Herrmann of SharkDefense (www.sharkdefense.com) have been working in conjunction with the BBFS since April 2003 to study the effects of chemical shark repellents. Two classes of repellents are under study: Semiochemicals and gustatory compounds.
Semiochemicals are chemical messengers or "clues" sharks may use to
orient, survive and reproduce in their specific environments. Certain
semiochemicals have the ability to trigger a flight reaction in sharks,
but these trace chemicals present unique difficulties for isolation and
detection. The possible use of semiochemicals as shark repellents was
proposed by Baldridge (1990) and by Rasmussen and Schmidt (1992). In 2001,
investigation of these possibilities led Eric M. Stroud and Michael
Herrmann to begin qualitative analysis on semiochemical entities using
captive sharks. A variety of analytical instruments and techniques were
employed to isolate possible candidates. The most promising semiochemical
candidates were scaled up, and during 2003, with the help of Dr. Samuel
Gruber, Grant Johnson, and the Bimini Biological Field Station, the team
was able to document a number of successful field tests on wild feeding
sharks. The results of these field tests were presented at the 2004 Joint
Meeting of Ichthyologists and Herpetologists 26 - 31 May, 2004, in Norman,
OK. Seven species of fish have been observed feeding in semiochemical
repellent clouds, while sharks were deterred.
Gustatory compounds are believed to affect taste receptors. In 8 species
of shark observed, all produce the same aversive mouth-opening reaction
towards the gustatory compounds. To date, 12 such compounds have been
identified, 2 of which are natural. As with semiochemicals, seven species
of bony fish do not demonstrate aversive behavior in the presence of the
gustatory compounds. Dosages as low as 100uL have terminated tonic
immobility in juvenile lemon and nurse sharks. The goal of this research
is to identify cost-effective, potent chemical shark repellents which are
environmentally conscious and compliant.
2005 research projects include monitoring the effects of chemical
repellents on the BBFS longlines, and delivery systems for the chemical
repellents. An aerosol-delivery repellent prototype is currently
undergoing tests at the BBFS.
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