Short-term behavioural response of common carp, Cyprinus carpio, to acoustic and stroboscopic stimuli

Deterrents that limit the dispersal of non-native fishes into waterways are important tools for managing aquatic invasions. Acoustic and stroboscopic stimuli may be used to limit the dispersal of common carp (Cyprinus carpio), a widely invasive species. This study exposed wild-caught common carp to stroboscopic, acoustic, or combined-stimuli treatments, to observe changes made in their activity and in the number of passes made across the deterrent. Mixed-effects models determined that for all treatments, common carp spent more time moving actively during the stimulus and post-stimulus periods than during the control period. Common carp deterrent passes differed according to treatments. In the stroboscopic treatment, passes only increased during the post-stimulus period, in the acoustic treatment there were no significant differences across stimulus periods, and in the combined treatment passes decreased during the stimulus period. These results indicate that stimulus-induced behavioural changes may be sustained for short periods of time (> 30 min) after the deactivation of a stimulus deterrent. Our study found a muted avoidance response in comparison to other acoustic deterrent studies, likely due to the lack of sufficient stimulus refuge. Finally, individuals that were exposed to both stimuli did not express additive behavioural responses in comparison to individuals that were only exposed to one stimulus type. Our findings highlight important considerations for deterrent technologies and directly quantify the behavioural response of combined deterrent stimuli.