Fish-protection devices at unscreened water diversions can reduce entrainment: evidence from behavioural laboratory investigations

Poletto, Jamilynn B.
Cocherell, Dennis E.
Mussen, Timothy D.
Ercan, Ali
Bandeh, Hossein
Kavvas, M. Levent
Cech, Joseph J.
Fangue, Nann A.
Diversion (i.e. extraction) of water from rivers and estuaries can potentially affect native wildlife populations if operation is not carefully managed. For example, open, unmodified water diversions can act as a source of injury or mortality to resident or migratory fishes from entrainment and impingement, and can cause habitat degradation and fragmentation. Fish-protection devices, such as exclusion screens, louvres or sensory deterrents, can physically or behaviourally deter fish from approaching or being entrained into water diversions. However, empirical assessment of their efficacy is often lacking or is investigated only for particular economically or culturally important fishes, such as salmonids. The Southern population of anadromous green sturgeon (Acipenser medirostris) is listed as threatened in California, and there is a high density of water diversions located within their native range (the Sacramento-San Joaquin watershed). Coupled with their unique physiology and behaviour compared with many other fishes native to California, the green sturgeon is susceptible to entrainment into diversions and is an ideal species with which to study the efficacy of mitigation techniques. Therefore, we investigated juvenile green sturgeon (188-202 days post-hatch) in the presence of several fish-protection devices to assess behaviour and entrainment risk. Using a large experimental flume (similar to 500 kl), we found that compared with an open diversion pipe (control), the addition of a trash-rack box, louvre box, or perforated cylinder on the pipe inlet all significantly reduced the proportion of fish that were entrained through the pipe (P = 0.03, P = 0.028, and P = 0.028, respectively). Likewise, these devices decreased entrainment risk during a single movement past the pipe by between 60 and 96%. These fish-protection devices should decrease the risk of fish entrainment during water-diversion activities.


Efficacy of a sensory deterrent and pipe modifications in decreasing entrainment of juvenile green sturgeon (Acipenser medirostris) at unscreened water diversions
Poletto, Jamilynn B.; Cocherell, Dennis E.; Mussen, Timothy D.; Ercan, Ali; Bandeh, Hossein; kavvas, M. Levent; Cech, Joseph J.; Fangue, Nann A. (2014-01-01)
Water projects designed to extract fresh water for local urban, industrial and agricultural use throughout rivers and estuaries worldwide have contributed to the fragmentation and degradation of suitable habitat for native fishes. The number of water diversions located throughout the Sacramento-San Joaquin watershed in California's Central Valley exceeds 3300, and the majority of these are unscreened. Many anadromous fish species are susceptible to entrainment into these diversions, potentially impacting po...
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The impact of the invasive ctenophore Mnemiopsis leidyi on the zooplankton community of the Caspian Sea was quantified according to food consumption and other major physiological activities (i.e. respiration and reproduction), coupled with field data on population structure. The adverse effects of M. leidyi on the zooplankton community during the first years of the invasion were tremendous for the Caspian Sea compared to other regions affected by this ctenophore. The impact was highest in summer, due to hig...
Citation Formats
J. B. Poletto et al., “Fish-protection devices at unscreened water diversions can reduce entrainment: evidence from behavioural laboratory investigations,” CONSERVATION PHYSIOLOGY, vol. 3, pp. 0–0, 2015, Accessed: 00, 2022. [Online]. Available: