Density‐Dependence and Environmental Conditions Regulate Recruitment and First‐Year Growth of Common Carp in Shallow Lakes

Abstract

AbstractRecruitment dynamics of fishes can determine their abundance and subsequent effects of adult populations on ecosystem properties. Common Carp Cyprinus carpio is a widespread invasive species that can exert negative density‐dependent effects on aquatic food webs. However, little is known concerning processes that regulate their recruitment. We used summer‐through‐fall electrofishing catch rates of age‐0 Common Carp to investigate the importance of biotic (stock size, prey availability, egg and juvenile predation, intraspecific competition) and abiotic (water level fluctuation, temperature, wind events) factors on recruitment and growth in 13 lakes across eastern South Dakota from 2008 to 2010. Mean relative abundance of age‐0 Common Carp 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. Recruitment also increased with spring–summer temperatures, decreased with wind events, and was affected by annual water level fluctuations. Age‐0 Common Carp growth, estimated by mean size in August, was highly variable (mean TL = 42–165 mm) and influenced by the abundance of conspecifics and wind events, indicating that density‐dependent interactions may have occurred during early life stages. Combined, our results suggest that the early life history of Common Carp is regulated by density‐dependent processes and abiotic environmental conditions, which provide new insights into mechanisms regulating recruitment of this widespread invasive species.