Factors Influencing First Year Growth and Recruitment of Common Carp Across Eastern South Dakota

Recruitment dynamics of invasive fishes, such as common carp Cyprinus carpio, can regulate the abundance and subsequent effects of adult populations on aquatic ecosystems.  However, little is known concerning processes regulating common carp recruitment.  We used summer-fall electrofishing catch rates of age-0 common carp to investigate the importance of biotic (stock size, prey availability, egg and juvenile predator abundance, intraspecific competition) and abiotic (water level fluctuation, temperature, wind events) factors on recruitment and growth in 13 populations across eastern South Dakota from 2008-2010.  Mean age-0 common carp relative abundance was highly variable -- spatially and temporally -- ranging from 0 to 152.2 fish per hour of electrofishing.  Ricker stock-recruitment models indicated that peak production of age-0 common carp occurred when adult common carp relative abundance was low but indicated that recruitment was also influenced by spring-summer temperature and wind.  Age-0 common carp growth, estimated by mean size at the end of August, was also highly variable (range 42-165 mm TL) and influenced by spring-summer wind and the abundance of conspecifics, potentially indicating density-dependent interactions during early life stages.  Our results indicate that common carp recruitment is highest when adult abundance is low and during years with warm spring and summer temperatures and low wind speeds, providing new insights into mechanisms regulating recruitment of this widespread invasive species.