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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