Quantifying Known Green Sturgeon, Acipenser medirostris, Spawning Habitat within the Upper Sacramento River, CA Using Side Scan Sonar

Green Sturgeon Acipenser medirostris, are a long-lived anadromous fish that are being managed as the Northern and Southern Distinct Population Segments (DPS) based on genetic analysis and spawning site fidelity.  Loss of spawning habitat and numerous concerns over concentration of the spawning population into a single watershed were cited as factors for listing the Southern DPS of Green Sturgeon as threatened under the Endangered Species Act on April 7, 2006.  Since the Federal listing, adult telemetry data generally indicates the spawning grounds extend between river kilometers 324 and 451.   Egg mat surveys have documented spawning within six hydraulically-active pools in this reach.  Utilizing side scan sonar technology and Geographic Information Systems, we quantified the total area of spawning habitat based primarily on substrates contained within the six spawning pools and developed methodologies to quantify the total spawning area likely to be accessible within the upper Sacramento River.  These data could provide valuable insight into one of the many Southern DPS Green Sturgeon biological data gaps recognized by the recovery planning process by providing a quantitative habitat assessment that could be used to guide restoration efforts and management of essential habitat within and outside the Sacramento River system.