Duane C. Chapman and Michael H. Hoff
Grass carp Ctenopharyngodon idella, black carp Mylopharyngodon piceus, bighead carp Hypophthalmichthys nobilis, and silver carp H. molitrix are native to Asia and are herein referred to as “Asian carps.” They have been popular aquaculture species for more than a thousand years due to their ability to feed efficiently, grow quickly, and reach relatively large sizes (Yuan 1993). Grass carp are primarily consumers of macrophytes or sometimes flooded terrestrial vegetation (Shireman and Smith 1983). Black carp are considered to be primarily molluscivores (Nico et al. 2005), whereas bighead carp and silver carp primarily filter plankton from the water column (Kolar et al. 2007).
Grass carp were imported to North America in 1963 as a biological control agent for aquatic weeds (Mitchell and Kelly 2006). Black carp were imported in the 1970s for use in aquaculture as a means of biological control of snails, intermediate hosts of trematode parasites of fish (Nico et al. 2005). Bighead carp and silver carp were imported in the early 1970s for use as a means of water quality management in wastewater treatment and aquaculture ponds, and later as a food fish (Kolar et al. 2007). All of these species have now escaped confinement. Grass carp, bighead carp, and silver carp are established in the Mississippi River basin, and grass carp are also established in the Trinity River basin of Texas (Schofield et al. 2005). Many adult black carp have been captured from the wild. Most of the captured black carp have been shown to be diploid and thus assumed to be fertile (Nico et al. 2011; Thomas et al. 2011; both this volume). The reproductive requirements of black carp are essentially similar to those of the other Asian carps that are already established; therefore, it seems probable that black carp will establish in North America (Nico et al. 2005).