Direct Field and Laboratory Evidence that a Combination of Egg and Larval Predation Controls Recruitment of Invasive Common Carp in Many Lakes of the Upper Mississippi River Basin

Abstract

Field and laboratory experiments tested the hypothesis that recruitment of the invasive Common Carp Cyprinus carpio is often controlled by the feeding activity of egg and larval predators in interconnected lakes of the upper Mississippi River basin. The survival of naturally spawned carp eggs was monitored in a seemingly typical lake by sampling the abundance of such eggs in spawning areas and in the diets of fish caught at these locations. Over 95% of the carp eggs found attached to spawning substrate disappeared within 4 d of spawning, at the same time that large numbers of eggs were found in the stomachs of Bluegills Lepomis macrochirus. Egg predation closely paralleled but lagged egg disappearance. Concurrent laboratory studies showed that carp eggs hatched after 4.75 d at lake temperatures, demonstrating that most (but perhaps not all) of the eggs had been eaten by egg predators prior to hatching. A second laboratory experiment found that Bluegills readily find and consume carp larvae while Black Bullheads Ameiurus melas do not, suggesting that predation on larvae contributes to carp recruitment. These data, together with previous studies of the survival of carp eggs placed into lakes and the distribution of young carp relative to various species of native fish, add strong support to the hypothesis that the recruitment of carp in interconnected lakes of the upper Mississippi River basin is often controlled by native fish predators.

Partial migration to seasonally‐unstable habitat facilitates biological invasions in a predator‐dominated system

“…However, with the exception of the sea lamprey Petromyzon marinus in the Great Lakes, few, if any, of such strategies have been developed. Our study suggests that common carp populations in lakes of the UMRB can be controlled by efforts that focus on preventing winterkills in connected water bodies to maintain high densities of native fishes that forage on carp eggs and larvae (Silbernagel and Sorensen ) and/or blocking migration routes to or from nursery areas. In systems that rarely winterkill and produce few year classes, carp populations could likely be managed by targeting winter aggregations of adults for removal every few years (Bajer et al ).…”

“…Carp in the UMRB show strong partial migration tendencies, and move out of the lakes in which they overwinter to spawn in hypoxia‐prone marshes (Bajer and Sorensen ). The migrants that exploit such areas have much higher recruitment success than residents that spawn in lakes, and whose eggs and larvae appear to suffer heavy predation by native fishes, especially the bluegill Lepomis macrochirus (Bajer et al , Silbernagel and Sorensen ). It has been thus hypothesized that partial migrations to winterkill‐prone marshes drive carp invasiveness (i.e.…”

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

“…Studies of biocontrol suggest that adding a top predator may suppress small predators (M€ uller & Brodeur, 2002;Vance-Chalcraft et al, 2007) and that functional traits of predators are often more important than the diversity of predatory community (Straub et al, 2008). We propose experimental tests to document differences in the ability of native micro-, meso-and large predators to locate and consume carp eggs, larvae and juveniles (Weber & Brown, 2012;Silbernagel & Sorensen, 2013). We suggest that differ-ent combinations of predators should be tested for biotic resistance over a gradient of lake productivities using realistic field settings.…”

“…For example, we are not aware of any of such analyses for invasive fish. For the common carp, which is one of better studied species, and whose recruitment has been investigated within several locations in North America and Australia (King et al, 2003;Phelps et al, 2008;Bajer & Sorensen, 2010;Bajer et al, 2012;Silbernagel & Sorensen, 2013;Weber & Brown, 2013a), ours is the first study to investigate this phenomenon across several ecoregions. Our approach identified a hierarchy of ecological filters that control carp recruitment at broad and fine spatial scales that had not been detectable by previous, more localized studies.…”

“…S1, S2). Although more than 100 fish species occur within this region, native communities in lakes and reservoirs are dominated by bluegills ( Lepomis macrochirus ) that are micropredators of carp eggs and larvae (Bajer et al ., ; Silbernagel & Sorensen, ); white crappies ( Pomoxis annularis ), black crappies ( P. nigromaculatus ) and yellow perch ( Perca flavescens ) that are mesopredators and might potentially forage on carp larvae and fry; black bullheads ( Ameiurus melas ), yellow bullheads ( A. natalis ) and brown bullheads ( A. nebulosus ) that are benthic mesopredators; and walleye ( Sander vitreus ), northern pike ( Esox lucius ) and largemouth bass ( Micropterus salmoides ) that are top predators that might forage on larger juvenile carp (Weber & Brown, ). In terms of numbers, these ten species collectively comprised 80% of all fish present in fisheries lake surveys throughout the region (see below).…”