Use of Drift Models to Understand Asian Carp Spawning and Early Life History

Bighead carp Hypophthalmichthys nobilis, silver carp H. molitrix, black carp Mylopharyngodon piceus, and grass carp Ctenopharyngodon idella spawn in flowing water and their eggs and larvae develop as they drift downstream. The eggs are generally thought to perish if they settle to the bottom.  Earlier predictions of suitable Asian carp spawning rivers were based simply on river length; however, we now have a better understanding of Asian carp reproductive biology and can use this knowledge to develop more refined models. Particle transport modeling has been used to estimate spawning locations based on egg and larvae collections, and subsequently applied to identify rivers in the Laurentian Great Lakes watershed that may provide adequate conditions for Asian carp reproduction and recruitment.  We describe how biological information (developmental rate, specific gravity of eggs, and behavior) and physical parameters (river velocity, hydrograph, temperature, turbulence) are combined to generate these models, and we provide a synopsis of ongoing and completed modeling.  We also describe uncertainties and data gaps associated with these assessments.