Assessing Spatial Overlap Among Two Asian Carp and One Native Planktivorous Species in the Upper Mississippi River

Paddlefish populations have been in dramatic decline since the mid-twentieth century as a result of overfishing, habitat destruction, and the construction of dams that have restricted seasonal migrations. Recent studies suggest that the accidental introduction of invasive Asian carp species has created direct and indirect interspecific interactions that may further decline paddlefish populations. Bighead carp and silver carp populations are increasing in abundance and expanding their upstream range in the Upper Mississippi River. Paddlefish and bigheaded carp are both adapted for filter feeding and have been found to occupy similar habitat. Our study aimed to quantify paddlefish and bigheaded carp spatial overlap by evaluating habitat use and selectivity in Pools 14 through 19. Paddlefish and bigheaded carp were manually tracked with VR100 receivers to assess habitat use and the magnitude of overlap. We evaluated the effect of introduced species on native taxa from their spatiotemporal overlap. From this information, we can assess the available refugia for this native species.