Unscreened Water-Diversion Pipes Pose an Entrainment Risk to the Threatened Green Sturgeon, Acipenser medirostris

Authors

Timothy D. Mussen, Sacramento Regional County Sanitation District
Dennis Chocherell, University of California, Davis
Jamilynn B. Poletto, University of Nebraska - LincolnFollow
Jon S. Reardon, University of California, Davis
Zachary Hockett, University of California, Davis
Ali Ercan, University of California, DavisFollow
Hossein Bandeh, University of California, DavisFollow
M. Levent Kavvas, University of California, DavisFollow
Joseph J. Cech Jr., University of California, DavisFollow
Nann A. Fangue, University of California, DavisFollow

Date of this Version

2014

Citation

PLoS ONE 9(1): e86321

Comments

Copyright 2014 Mussen et al.

Open access

doi:10.1371/journal.pone.0086321

Abstract

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 (3560.6 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.