Effects of Common Carp on Reproduction, Growth, and Survival of Largemouth Bass and Bluegills

Abstract

The common carp Cyprinus carpio was introduced to North America more than a century ago, but little research has focused on interactions between this invasive species and native fishes. We used large mesocosms (600 m²) within drainable 0.4-ha ponds to examine the effects of adult common carp on (1) reproduction of largemouth bass Micropterus salmoides and bluegills Lepomis macrochirus and (2) growth and survival of the larvae and juveniles of these centrarchid species. In separate enclosures, adult bluegills or largemouth bass were stocked with or without common carp. In enclosures with common carp, turbidity was substantially higher, but both centrarchid species spawned and the densities and sizes of larval largemouth bass and bluegills were similar to those of larvae in enclosures without common carp. As juveniles grew, largemouth bass survived at a higher rate but were smaller in enclosures containing common carp compared with largemouth bass in enclosures without common carp. In a second experiment, we stocked known numbers of older juvenile centrarchids into enclosures and found decreased growth for both largemouth bass and bluegills. However, survival of largemouth bass was again higher in enclosures with common carp. Although centrarchid spawning was successful and larval growth and survival did not decrease in the presence of common carp, centrarchid growth slowed at the juvenile stage, probably due to food resource limitation resulting from direct competition with common carp for invertebrate forage, high turbidity caused by common carp, or both of these factors.