Habitats and Movements of Shovelnose Sturgeons in the Upper Mississippi River

Abstract

Habitats and movements of shovelnose sturgeons Scaphirhynchus platorynchus in Pool 13 of the upper Mississippi River were ascertained during April-September 1982 by radio-telemetry, drifted trammel net, and mark-recapture methods. The fish were mostly sedentary, but sometimes they moved up to 11.7 km/d. Most movements occurred in May and July and the fewest in April and June. Long-range movements up to 17 km were noted between activity centers (areas occupied for 3–93 d). Among 22 radio-tagged shovelnose sturgeons, eight showed homing behavior. The fish were frequently located at water depths of 2–7 m, where currents were 20–40 cm/s at the bottom and 40–70 cm/s at the surface. During spring high-river stages, shovelnose sturgeons were located most frequently downstream from wing dams (rock and brush structures built perpendicular to river flow in the main channel), downstream from closing dams (rock and brush structures built across side channels), and at the border of the main channel within 50 m of shore. During low-river stages in summer, they were usually close to or in the main channel or on the upstream side of wing dams and closing dams.