Unscreened water-diversion pipes pose an entrainment risk to the threatened green sturgeon, Acipenser medirostris.
Over 3,300 unscreened agricultural water diversion pipes line the levees and riverbanks of the Sacramento River (California) watershed, where the threatened Southern Distinct Population Segment of green sturgeon, Acipenser medirostris, spawn. The number of sturgeon drawn into (entrained) and killed by these pipes is greatly unknown. We examined avoidance behaviors and entrainment susceptibility of juvenile green sturgeon (35±0.6 cm mean fork length) to entrainment in a large (>500-kl) outdoor flume with a 0.46-m-diameter water-diversion pipe. Fish entrainment was generally high (range: 26-61%), likely due to a lack of avoidance behavior prior to entering inescapable inflow conditions. We estimated that up to 52% of green sturgeon could be entrained after passing within 1.5 m of an active water-diversion pipe three times. These data suggest that green sturgeon are vulnerable to unscreened water-diversion pipes, and that additional research is needed to determine the potential impacts of entrainment mortality on declining sturgeon populations. Data under various hydraulic conditions also suggest that entrainment-related mortality could be decreased by extracting water at lower diversion rates over longer periods of time, balancing agricultural needs with green sturgeon conservation.
Wildlife, Fish, and Conservation Biology Department, University of California Davis, Davis, California, United States of America.
Timothy D
TD
Mussen
Wildlife, Fish, and Conservation Biology Department, University of California Davis, Davis, California, United States of America.
Dennis
D
Cocherell
Wildlife, Fish, and Conservation Biology Department, University of California Davis, Davis, California, United States of America.
Jamilynn B
JB
Poletto
Wildlife, Fish, and Conservation Biology Department, University of California Davis, Davis, California, United States of America.
Jon S
JS
Reardon
Department of Civil and Environmental Engineering, University of California Davis, Davis, California, United States of America.
Zachary
Z
Hockett
Department of Civil and Environmental Engineering, University of California Davis, Davis, California, United States of America.
Ali
A
Ercan
Department of Civil and Environmental Engineering, University of California Davis, Davis, California, United States of America.
Hossein
H
Bandeh
Department of Civil and Environmental Engineering, University of California Davis, Davis, California, United States of America.
M Levent
ML
Kavvas
Wildlife, Fish, and Conservation Biology Department, University of California Davis, Davis, California, United States of America.
Joseph J
JJ
Cech
Wildlife, Fish, and Conservation Biology Department, University of California Davis, Davis, California, United States of America.
Nann A
NA
Fangue
D057914:Agricultural Irrigation; D000818:Animals; D002140:California; D056727:Endangered Species; D005260:Female; D005399:Fishes / Q000502:physiology*; D008297:Male; D045483:Rivers; D013550:Swimming