Using Food Web Modeling to Determine Effects of Increased Exploitation on Invasive Carps in the Middle Mississippi River

Since the beginning of fisheries management in North America, nonnative fish species have been introduced to new waters with to supplement existing populations often with the opposite effects which leads to removal efforts. The objective of this study was to determine the amount of harvest required to control invasive carps in a large river system and its impact on remaining fish groups. We developed a mass balance trophic model of the Mississippi River near Cape Girardeau, MO using Ecopath with Ecosim software. In doing so, we developed biomass, production, consumption and diet composition estimates for 31 fish groups using Long Term Research Monitoring element data. Using the Ecosim component of the software we modeled increasing amounts of harvest of invasive carps from 5-100% of their initial biomass to determine whether increased harvest would either benefit or hinder other species. Common Carp and Grass Carp were more susceptible to increased harvest however, twice as much effort was needed before Silver Carp and Bighead Carp showed signs of being overfished. Ultimately, this information can be used by fisheries professionals to evaluate management policies promoting the removal of these species from our waters, resulting in enhanced populations of native fish.