Life History Attributes of Asian Carps in the Upper Mississippi River System
ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS
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The Upper Mississippi River UMR system starts at the confluence of the Ohio River at Cairo, Illinois, and serves as a conduit for many aquatic invasive species to enter the waterways of the central and northern interior of the United States, including the Great Lakes. One well-established group found in this waterway is the Asian carps including the common carp Cyprinus carpio, grass carp Ctenopharyngodon idella, and two recent invaders, the bighead carp Hypophthalmichthys nobilis and silver carp H. molitrix. Their impact is not minor. In the UMR and Missouri River drainages, common carp typically contributes more tonnage to the commercial fishery than any other fish species Pflieger 1997. Although the impact of the newly established Asian carp species is currently unknown, benefits to native fishes are unlikely Laird and Page 1996. The risk is not restricted to the inland rivers of the United States. If these species breach the electric barrier constructed by the U.S. Army Corps of Engineers in the Chicago Sanitary and Ship Canal, then they will threaten the Great Lakes as well Pegg and Chick 2002, Kolar et al. 2005. Although these species have been widely introduced throughout the world for food, the native range of silver and bighead carp is eastern Asia Fuller et al. 1999. In the early 1970s, these fishes were introduced into the southern United States for private aquaculture. By the 1980s, these species occurred in public waters, probably escapees from hatcheries Freeze and Henderson 1982. Successful reproduction of both species is occurring in the UMR and Missouri drainages Burr et al. 1996, Koel et al. 2000, Schrank et al. 2003. Population densities of silver carp increased dramatically in the early 2000s Chick and Pegg 2001, greatly increasing the visibility of this species, which is notorious for breaching the surface of the water in large aggregations.