Patterns of Migration and Habitat Use By Green Sturgeon Acipenser medirostris in the Vicinity of a Proposed Wave Energy Project in Oregon

Sites selected for wave energy projects are typically near estuaries and bays.  A wave energy project was planned in the ocean at depths of 62–69 m near Reedsport, Oregon, northwest of the Umpqua River estuary.  Green Sturgeon (Acipenser medirostris) use this estuary during the spring–fall, presumably for feeding.  A “before-after” study was designed to identify potential interactions between the wave energy project and Green Sturgeon, but the project was recently terminated.  Nonetheless, understanding movements and habitat use of Green Sturgeon near estuaries and bays is important for site selection of future ocean energy projects.  Using automated acoustic receivers within and outside of the proposed project area, we monitored the occurrence of Green Sturgeon tagged with coded ultrasonic transmitters, which were affixed by other researchers working on unrelated projects.  We detected 248 Green Sturgeon at depths of 12–110 m from January 2013 through June 2014.  Green Sturgeon were detected on 492 of 515 monitoring days.  Peak detections occurred at 50–70 m.  Results suggest that the ocean immediately offshore and upcoast/downcoast of estuaries that support Green Sturgeon may be important Green Sturgeon habitats, and significant numbers of this species may interact with wave energy projects in such areas.