Modifying Flows at Mississippi River Dams to Stop Bigheaded Carp Passage

To reach the Upper Mississippi River, bigheaded carps (silver carp, Hypopthalmichthys molitrix, and bighead carp, H. nobilis) must first pass through its locks and dams which, depending on river stage and operating conditions, can create velocity fields that might deter fish passage.  To test what extent current dam operations block bigheaded carp and whether alterations to gate operation could enhance this feature with minimal impacts to native fish passage and scour, we developed an agent-based fish passage model.  The fish passage model combines computational fluid dynamics (CFD) models of fluid flow through the structures with empirical swimming-fatigue relationships to simulate how and where fish might pass.  To then test whether and how bigheaded carp might pass, the model is supplied with newly generated swimming performance data to identify the paths of least resistance.  Preliminary models suggest Lock and Dam #8 (Genoa, WI) already impedes adult bigheaded carp passage and minor modifications to gate operation can further decrease the likelihood of passage.  In this talk we will discuss adult bigheaded carp swimming abilities, model results, and how changes to gate operation can be used for carp management purposes in the Mississippi River. (Funded by Minnesota Environmental and Natural Resources Trust Fund).