What Drives The Recruitment Of One Of The World's Most Invasive Fish: An Analysis Of Common Carp Recruitment Across Three States and Eight Ecoregions

Although the common carp (Cyprinus carpio) is one of the world’s most invasive fish, processes that drive its recruitment have never been analyzed across more than one ecoregion. In this study, we identified carp recruitment patterns associated with differences in fish communities and physico-chemical characteristics that occurred in lakes and reservoirs of eight ecoregions in Minnesota, South Dakota and Nebraska. Of the 80,000 combinations of systems and years that were analyzed, recruitment was only noted in 341 suggesting that carp recruit rarely and only if specific conditions are met. Although recruitment varied considerably among ecoregions, it appeared to be explained by the same processes. Recruitment occurred only in systems that were productive (Secchi depth < 1.5 m) and shallow (<8m) but only if they also had low densities of bluegill (Lepomis macrochirus), which were previously shown to be predators of carp eggs and larvae. Lake surface area or abundance of other fish species appeared to have lower influence on carp recruitment. Our results suggest that the recruitment of common carp in the Midwest is fundamentally controlled by lake productivity (i.e. abundance of larval food) but even in productive lakes, it can be suppressed by predation.