Passage survival of European and American eels at Francis and propeller turbines

Published source details Heisey P.G., Mathur D., Phipps J.L., Avalos J.C., Hoffman C.E., Adams S.W. & De‐Oliveira E. (2019) Passage survival of European and American eels at Francis and propeller turbines. Journal of Fish Biology, 95, 1172-1183.
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This study is summarised as evidence for the following.

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Modify design of underwater turbines

A replicated, site comparison study in 1997, 2009–2010 and 2015 at seven hydropower stations along rivers in France and the USA (Heisey et al. 2019) found that European eels Anguilla anguilla and American eels Anguilla rostrata passing through Francis turbines had greater survival and lower injury rates compared to propeller turbines. Overall, average eel survival was higher (95%) and injury rate lower (13%) at Francis turbines than propeller turbines (survival: 81%, injury rate: 26%). Released eels that did not pass through turbines (controls) had a survival rate of 99%. The most common injury at Francis turbines was bruising, whereas severed bodies were most frequently observed at propeller turbines. Passage survival of European eels was estimated at three hydropower stations (three propeller turbines) in France in 2009–2010. Passage survival of American eel was estimated at four hydropower stations (four propeller turbines, five Francis turbines) in the USA in 1997 and 2015. Wild-caught eels provided by local fishers were radio-tagged and released within turbine intakes (30–300 eels/turbine). For comparison, control eels (25–134 eels/turbine) were released downstream of each station. Eels recaptured downstream (96–98% of ‘turbine’ eels, 95–100% of control eels) were visually assessed for injuries, and live eels placed in holding pools for 48 h.

(Summarised by: Sam Reynolds)