Aspects of the Early Life History of Bighead and Silver Carps Pertaining to Spawning River Requirements

Bighead carp Hypophthalmichthys nobilis and silver carp H. molitrix (hereafter, the bigheaded carps) are large cyprinids native to Asia that have invaded the large rivers of the Central United States.  They are thought to have precise requirements for spawning and for survival of the eggs and larvae.  Understanding which rivers provide the minimum requirements for recruitment past the larval stages is a critical need for management and control of these invasive fishes.  However, important aspects of the life history of bigheaded carps need to be characterized, so that fisheries managers can more effectively determine which rivers might be used for recruitment.  We here describe important early life history parameters such as egg and larvae development rates at different temperatures; egg specific gravity and sinking rate at different ages;  and behavior of larvae, including start of vertical swimming, start of horizontal swimming, and age at which they begin to leave the drift.  Results are generated from eggs and larvae from both species spawned in the lab and cultured at different temperatures and environmental conditions, and from field collections of eggs and larvae from the Missouri River and its tributaries.