Influence of Habitat on Young-Of-Year Shovelnose Sturgeon Prey Use

The lower Missouri River has been highly modified and it is hypothesized that loss of shallow-water habitat (SWH) has decreased prey items and survivability for young-of-year (YOY) Sturgeon.  Early life stages of Sturgeon depend on these habitats for recruitment.  In this study, we sought to quantify diets of Shovelnose Sturgeon (Scaphirhynchus platorynchus) and how they vary by the amount of SWH.  Five reaches (from 24 to 41 km in length) between Kansas City, MO and Saint Louis, MO that varied in amount of SWH were sampled bi-monthly from May through October 2014.  We captured 506 YOY Sturgeon ranging from 15 to 120 mm FL.  We found that diet items were restricted to mainly three macroinvertebrate orders: Diptera, Ephemeroptera, and Trichoptera.  Less than 5% of YOY Sturgeon had empty guts. Of the remaining fish, we identified 80,909 diet items, of which 93.55% were Diptera larvae, 5.95% Diptera pupae, 0.45% Ephemeroptera, and 0.05% Trichoptera.  Prey-specific abundance varied according to length category and reach location for Diptera larvae and Ephemeroptera but no interaction was present for Diptera pupae.  These results will help identify restoration goals to improve conditions suitable for YOY Shovelnose Sturgeon.