Potential for Restoration of Floodplain Habitats in Large Rivers: Fish Community Response and the Mitigating effects of Invasive Species, Droughts and Flooding

Floodplain habitats are among the most productive in the world and the importance of restoring connection between river and floodplain is often promoted. The Nature Conservancy’s >1600 ha Emiquon and >800 ha Merwin Preserves on the Illinois River are large scale restoration projects meant to enhance multiple aspects of a naturally functioning large river system including the productivity of native and sport fisheries. The practical outcome of several important fisheries management theories are seen playing out in these two projects including the existence of threshold responses, the importance of the flood pulse, implications of drought and flood events, and interactions with invasive species like Asian Carp. In particular population dynamics at Emiquon confirm the science that says that “just add water” is not enough. Water level fluctuation is needed in order to maintain healthy reproduction and a resilient native fish community. In contrast, Merwin has experienced drought and significant flooding and the native and sport fish communities have not been sustained. If fisheries management and productivity in large rivers continue to improve, the type of responses seen at Emiquon and Merwin can be thought of as expectations and lessons learned need to be incorporated into the next generation of projects.