The Use of Chemical Stimuli in the Control of Asian Carp

Our previous research has determined that invasive bighead and silver carp are responsive to conspecific pheromones both physiologically and behaviorally.  Asian carp avoid alarm pheromones present in skin extracts as a means of avoiding predators, and are also attracted to chemical cues released by groups of conspecifics as a means of maintaining schooling behavior in turbid water conditions.  Sex pheromones are olfactory signals that mediate conspecific reproductive interactions.  Physiological screening assays (electro-olfactograms) have indicated high sensitivity of the olfactory system for certain hormonal metabolites associated with the sex pheromones and behavioral assays verified an attractant response to those certain hormonal metabolites.  We conducted a series of “proof-of-concept” pond studies to determine if attractive sex pheromone production could be hormonally induced in females with the aim of using caged hormonally implanted females as a source of attractive pheromone to aid in the capture of wild Asian carp.  Chemical analyses of the water in which hormonally induced females were held indicated high concentrations of prostaglandin metabolites characteristic of carp pheromone.  Preliminary tests indicate free ranging silver and bighead carp have a tendency to respond to hormonally implanted caged fish. We also observed a consistent attractant response to a positive food control stimulus during pond trials with Didson (Dual Frequency Identification Sonar) sonar technology effectively capturing the fish response.  We are currently evaluating methods to address behavioral verification of the effectiveness of integrated control methods (pheromones, fish toxins) using technologies such as Didson and PIT-tags.