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