Biomanipulating Effect Of Grass Carp (Ctenopharyngodon Idella Val.) In Artificial Water Channels

The grass carp (Ctenopharyngodon idella Val.) is an important species used to control invasive aquatic macrophytes in many parts the world. In this study, we assess the diet of grass carp introduced to two artificial channels overgrown with aquatic vegetation. We examined forty 7+ to 9+ carp (517-814 mm standard length) sampled in the summers of 1998 and 2015. Aquatic vegetation was the dominant dietary item, with insects, fruit and vegetable remains (stones of Prunus sp., potato remains) and detritus a minor part of the diet. Aquatic plant biomass declined significantly at the study sites after carp were introduced, with coverage reduced from 65-70% of the water's surface in summer 1998 to 10% in summer 2015.