Acoustic conditioning demonstrates the presence of the partial reinforcement extinction effect in common carp (Cyprinus carpio)

The partial reinforcement extinction effect (PREE) occurs when a conditioned response is more resistant to extinction when reinforced unpredictably versus continuously. The PREE has been observed in many species; however, our knowledge of the PREE in fishes is limited. In this study, we investigated two different reinforcement methods, continuous and partial, while using Pavlovian conditioning to acoustically condition common carp (Cyprinus carpio), a highly invasive species, to swim into a feeding ring (conditioned behaviour) where they would receive a food reward at the onset of a 400 Hz sound stimulus. The extinction rates of the conditioned behaviour were compared following cessation of the food reward. Using binomial generalized linear mixed-effect regressions we showed that tanks subjected to partial reinforcement were expected to have a higher proportion of carp exhibiting the conditioned behaviour up to two times longer than tanks subjected to continuous reinforcement, consistent with the PREE. Carp in partial reinforcement tanks continuously responded for up to 30 days, while responses in continuous reinforcement tanks typically ceased by day 9. Our findings support common carp management strategies that use baiting to train carp to form feeding aggregations that can be removed en masse from lakes and suggest that such baiting strategies may benefit from partial conditioning protocols, saving on both labour and bait.