Seasonal changes in habitat suitability for adult shovelnose sturgeon in the lower Mississippi River

Abstract

Shovelnose sturgeon Scaphirhynchus platorynchus are a large-river fish distributed throughout the Mississippi River basin, including the lower 1,533 km of the Mississippi River where riverine habitat has been and continues to be modified for navigation and is a potential site for development of instream hydrokinetic electric power generation. Information about habitat use and preference is essential to future conservation efforts. Shovelnose sturgeon have previously been found to select particular habitat types, and these selected habitats vary seasonally; although these past analyses do not consider the selected habitats in a landscape context. We used ecological niche factor analysis (ENFA) that uses distributions of telemetry locations and environmental variables to model habitat suitability in a landscape context. We recorded 333 locations of shovelnose sturgeon during July–December 2013 that included periods of relatively high and low river stages. The ENFA analysis indicated high-suitability locations were in or near deep water during both high and low river stages. During high river stages, high-suitability locations were near island tip habitat, deep water, and steep bottom slope and far from main channel habitat. During low stages, high-suitability locations were in or near deep water and main channel habitat and far from secondary channel and wing dike habitats. This landscape-scale analysis supports seasonal shifts in habitat use and provides insights that can be used to inform habitat conservation and management to benefit shovelnose sturgeon in the lower Mississippi River and possibly other large rivers.