Unscreened water-diversion pipes pose an entrainment risk to the threatened green sturgeon, Acipenser medirostris

Timothy D Mussen; Dennis Cocherell; Jamilynn B Poletto; Jon S Reardon; Zachary Hockett; Ali Ercan; Hossein Bandeh; M Levent Kavvas; Joseph J Cech Jr; Nann A Fangue

doi:10.1371/journal.pone.0086321

Unscreened water-diversion pipes pose an entrainment risk to the threatened green sturgeon, Acipenser medirostris

PLoS One. 2014 Jan 15;9(1):e86321. doi: 10.1371/journal.pone.0086321. eCollection 2014.

Affiliations

¹ Wildlife, Fish, and Conservation Biology Department, University of California Davis, Davis, California, United States of America.
² Department of Civil and Environmental Engineering, University of California Davis, Davis, California, United States of America.

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 (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.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Agricultural Irrigation
Animals
California
Endangered Species
Female
Fishes / physiology*
Male
Rivers
Swimming

Grants and funding

The authors thank the California Department of Fish and Wildlife's Ecosystem Restoration Program (Agreement # E0783004 to NAF and JJC) and the University of California Agricultural Experiment Station (grant no. 2098-H to NAF) for providing funding. This research indirectly benefited from funding from the U.S. Department of Interior's Anadromous Fish Screen Program. JBP was supported through a National Science Foundation (NSF) Graduate Student Fellowship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.