Natural Resources, School of


Document Type


Date of this Version



Canadian Journal of Fisheries and Aquatic Sciences 71:7 (July 2014).

doi: 10.1139/cjfas-2013-0556


Copyright © 2014 Jamilynn B. Poletto, Dennis E. Cocherell, Natalie Ho, Joseph J. Cech, Jr., A. Peter Klimley, and Nann A. Fangue. Published by Canadian Science Publishing. Used by permission.


Water diversions that extract fresh water for urban, industrial, and agricultural uses, as well as export to southern California, are prevalent throughout the Sacramento–San Joaquin watershed. Many water diversions are fitted with fish-exclusion screens designed to prevent fish from entrainment (i.e., being drawn in). The impact of fish screens on the behavior of migrating juvenile fishes remains largely unknown, especially for threatened species such as sturgeon. We placed individual juvenile green (Acipenser medirostris) or white (Acipenser transmontanus) sturgeon in a laboratory swimming flume in the presence of standard fish screens (2 mm bar spacing) at two field-relevant water velocities (20.4 ± 0.1 and 37.3 ± 0.3 cm·s−1). Fish were tested at 18°C for 15 min during the day or night and in the presence of possible behavioral deterrents. Behavioral responses, including screen contacts, impingements, and time spent near screens were quantified. Green sturgeon contacted and impinged upon the screens twice as frequently as white sturgeon and also differed in how their behaviors were altered by water velocities and time of day. Our results are informative in developing effective management strategies to mitigate the impacts of water diversions on sturgeon populations and suggest that effective restoration strategies for both species should be considered separately.