Effects of Predator Species, Vegetation, and Prey Assemblage on Vulnerability of Age-0 Common Carp to Predation

Common carp Cyprinus carpio is a widespread invasive species that can become highly abundant and exert strong effects on aquatic ecosystems.  Management of shallow eutrophic lakes often includes controlling common carp populations, but few options have been evaluated to control this detrimental invader.  Predator manipulations are often implemented to regulate the abundance of prey fishes or undesirable species, but success is dependent in part upon predator preference patterns and prey vulnerability.  We evaluated prey selection and feeding behavior of five common piscivores (flathead catfish Pylodictis olivaris, largemouth bass Micropterus salmoides, smallmouth bass M. dolomieu, walleye Sander vitreum, and northern pike Esox lucius) foraging on juvenile common carp and two alternative prey – fathead minnow Pimephales promelas and yellow perch Perca flavescens – at variable densities in vegetated and non-vegetated habitats.  Common carp were generally neutrally or preferentially consumed, regardless of predator, prey density, or habitat complexity.  Fathead minnow were selected for or neutrally selected when common carp were neutrally selected or preferred, respectively.  Yellow perch were generally selected against.  Predator behaviors indicated common carp and fathead minnow were easily captured whereas yellow perch were not.  Once captured, common carp required the longest handling time followed by yellow perch and fathead minnow.  Our results indicate that common carp are vulnerable to a variety of predators and that habitat and abundance of alternative prey has little influence on predator preference for this invasive species.