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

Abstract

Recruitment 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.

Exploitation by Common Carp (Cyprinus Carpio) of A Floodplain Wetland of The Lower River Murray Under Drought and Flooding Conditions

“…this is because the temporal frame of the current study period, despite the three seasons of sampling, was too short to encompass the stochasticity of recruitment events linked to carp population dynamics (see Forsyth et al 2013). In fact, these are thought to occur at larger spatial and temporal scales compared to those of most native fishes (Nicol et al 2004) and are likely to be the result of a complex interaction between abiotic and biotic factors (Weber & Brown 2013). In this respect, it has been hypothesised that unstable floodplain wetland habitats of the MDB that experience severe droughts and floods along with summer hypoxia on a quasi-annual basis may be acting in a similar way to North american lakes subject to winter-time hypoxia due to prolonged snow cover (Bajer & Sorensen 2010).…”

Across‐ecoregion analysis suggests a hierarchy of ecological filters that regulate recruitment of a globally invasive fish

“…Similar conditions are not thought to have occurred in lakes of the Northern Forest ecoregion (Ramstack et al ., ; Heiskary & Wilson, ). Finally, carp recruitment is usually highest when the density of adults is low; thus, niche construction effects are negligible (Bajer et al ., ; Weber & Brown, ). Although the carp can modify habitats it invades and might in some circumstances promote its own success, its invasions seem to follow pre‐existing patterns in nutrient concentration.…”

“…Nevertheless, due to their extensive use over many years, these surveys have been shown to be important in elucidating invasion patterns (Kulhanek et al ., ,b). With these data, we quantified relative abundance (mean CPUE) of age‐0 carp (carp < 150 mm) as an index of recruitment (Phelps et al ., ; Bajer et al ., ; Weber & Brown, ), relative abundance of adult carp (carp > 300 mm) as an index of propagule pressure and relative abundance of the dominant species of native predators: bluegill, crappies (white and black combined), bullheads (black, yellow and brown combined), yellow perch, walleye and northern pike. Largemouth bass was not used in analyses because night‐time electrofishing surveys are needed to accurately assess its abundance, which we lacked for most lakes.…”

“…In this approach, the intercept β 0 is adjusted as follows: ; where τ = 0.28 is a fraction of events in population (the rate with which recruitment would occur in a random sample of lakes), which we estimated using data reported in Bajer et al . () and Weber & Brown (), and = 0.068 is fraction of events in sample (lake surveys used in this study). In the case of this study, the fraction of events (recruitment occurrence) was lower than expected because fisheries surveys often focus on lakes with abundant sport fish populations and rarely include seasonally unstable marshes where carp are more likely to recruit (Bajer et al ., ).…”

“…Studies in lakes of the upper Mississippi River Basin in North America suggest that recruitment is sporadic and often controlled by micropredators (small sunfishes; Lepomis spp.) that consume carp eggs and larvae (Bajer et al ., ), while surveys of prairie lakes of South Dakota show consistent recruitment influenced mainly by the abundance of adults and weather conditions (Phelps et al ., ; Weber & Brown, ). We hypothesize that these apparently conflicting findings are attributable to regional differences in environmental conditions, predatory communities and propagule pressure that may support a common hierarchical pattern if analysed from a broad geographic perspective.…”