Movements of Shovelnose Sturgeon throughout Life History Inferred from Otolith Microchemistry

Shovelnose sturgeon are obligate large-river fishes whose movements as they correspond to life history are poorly known.  As part of a pre-mitigation assessment for a fish passageway at Prairie Du Sac Dam on the Lower Wisconsin River, we used otolith microchemistry to determine how shovelnose sturgeon—which spawn in the Lower Wisconsin River—use Mississippi and Lower Wisconsin river habitats throughout life history.  Otolith microchemical analyses provide evidence that connectivity between the Wisconsin and Mississippi rivers is important to shovelnose sturgeon throughout life history.  For example, while field collection data show the focal species spawns in the Lower Wisconsin River, our otolith microchemical analyses suggest that the Mississippi River provides critical early life history habitat.  The apparent necessity of biotic connections between the Wisconsin and Mississippi rivers for large river species underscores the importance of maintaining connections between large mainstem rivers and their tributaries.