Assessment of Non-Planktonic Food Sources for Bigheaded Carps in the Laurentian Great Lakes

In recent years, concern has mounted over the potential for invasive bigheaded carps (bighead carp Hypophthalmichthys nobilis and silver carp H. molitrix) to colonize the Great Lakes.  Bioenergetics models have indicated that planktonic foods may be inadequate for bigheaded carps to successfully invade large portions of the Great Lakes.  Bigheaded carps are primarily planktivores but in some cases switch to non-planktonic food such as detritus. Cladophora is a filamentous algae common in the littoral zones of the Great Lakes.  It has become much more abundant since the invasion of dreissenid mussels (Driessena spp.). Dreissenid mussel feces and pseudofeces are fine, organically enriched particles that have become highly available as a result of the dreissenid invasion.  We evaluate Cladophora and detritus enriched by dreissenid mussel feces and pseudofeces as potential food sources abundant in the Great Lakes that might be used by bigheaded carps in lieu of plankton.    We use changes in weight and caloric content of bigheaded carps fed these alternative foods to evaluate food suitability.