Acoustic and Carbon Dioxide Deterrents for Invasive Bigheaded Carps (Hypophthalmichthys molitrix and H. nobilis)

Invasive bigheaded carps (Hypophthalmichthys molitrix and H. nobilis) are two aquatic invasive species that are expanding their range throughout the Mississippi River Basin. These carps display negative phonotaxis to broadband sound, and thus, acoustic deterrents have shown promise for managing their populations. Numerous dams block direct upstream access for the carp; however, fish can bypass these physical obstructions by swimming through navigational locks. Nonphysical acoustic deterrents have the advantage of not effecting navigation, are relatively inexpensive, and could be tuned above the hearing range of non-ostariophysian fishes. Fish also react negatively to high levels of carbon dioxide, and it has been proposed to combine these two stimuli into one deterrent system to reduce potential habituation to long-term acoustic playbacks and increase barrier efficacy. Here, the possible synergies of combining these two stimuli into integrated deterrent systems are evaluated.