Non-native silver Carp Fail to Generalize Behavior when Exposed to Odors from Three North American Predators

Predator-prey interactions exert significant influence over the survival of juvenile fish cohorts. Therefore, susceptibility of a habitat to invasion is influenced by the capacity of native predators to regulate invasive species through consumption. Closely related predators often share similar characteristics (e.g., odors or body morphometry), and prey species capable of expressing generalized behavioral responses to predators with similar characteristics may increase their chances for survival. Here, we examined how naïve juvenile silver carp (Hypophthalmichthys molitrix), an invasive Asian carp, respond to three predator odors from predators commonly found in Midwestern lakes and rivers of the USA. We tested two congeneric species of bass (largemouth Micropterus salmoides and smallmouth M. dolomieu bass) and one outgroup, longnose gar (Lepisosteus osseus). Additionally, we tested how silver carp conditioned to recognize the odor of one group, largemouth bass, responded to the predator odors of the congeneric species and the outgroup. We found that juvenile silver carp showed no innate response to any of the three predator odors. Additionally, although they could be conditioned to recognize predator odors from largemouth bass, they were unable to generalize predator odors to smallmouth bass or longnose gar odor. These results suggest that invasive species could be less likely to persist in environments with diverse predator communities than environments of equal densities with uniform predator communities and that future studies should continue to explore this area as well as focus on understanding dynamics in predator-prey interactions of invasive species.