Grass Carp Population Dynamics in the Middle Mississippi River

Fish can be imported to a new region of the world to perform a specific function where they may have the opportunity to become invasive. Grass Carp (Ctenopharyngodon idella) are an invasive fish in the Mississippi River Basin. Potential control of invasive fish relies on knowledge of specific population dynamics. It is commonly assumed that Grass Carp share characteristics (i.e., fast growth and high mortality) with Asian carp (i.e., Bighead Carp Hypophthalmichthys nobilis and Silver Carp H. molitrix) but our findings suggest they are more similar to Common Carp (Cyprinus carpio) in terms of growth and mortality. Results suggest that based on spawning potential ratio models, 28% exploitation of Grass Carp greater than 700mm could possibly recruitment overfish the population. Studies have shown that this invasive fish can consume high quantities of aquatic macrophytes. Aquatic macrophytes are a highly important component to phytophilic fishes in areas connected to the Middle Mississippi River (i.e., the Upper Mississippi River pools). The fact that these fish can consume large amounts of vegetation especially at large sizes coupled with their long-lived nature makes management imperative for sustaining current ecosystems.