Tests of two types of bypass for downstream migration of eels at a small hydroelectric power plant
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Published source details
Gosset C., Travade F., Durif C., Rives J. & Elie P. (2005) Tests of two types of bypass for downstream migration of eels at a small hydroelectric power plant. River Research and Applications, 21, 1095-1105.
Published source details Gosset C., Travade F., Durif C., Rives J. & Elie P. (2005) Tests of two types of bypass for downstream migration of eels at a small hydroelectric power plant. River Research and Applications, 21, 1095-1105.
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This study is summarised as evidence for the following.
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Install bypass systems alongside exclusion devices Action Link |
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Install bypass systems alongside exclusion devices
A study in 1999–2002 in a river in Halsou, France (Gosset et al. 2005) reported that a bypass system located on the river bottom alongside a bar rack at a hydropower station was used by more European silver eels Anguilla anguilla for downstream migration than a bypass located at the surface. Results are not based on assessments of statistical significance. Over three years, out of 70 tagged eels, 15–19 eels (21–27%) used the bottom bypass and 3–5 eels (4–7%) used the surface bypass, while 10–13 eels (14–19%) passed through the turbines, 3–4 eels (4–6%) passed over the weir and one eel (1%) used a fishway. Over three years, a total of 637 eels were captured after passing through the surface and bottom bypasses. A surface bypass (flap gate; 1.4 m length, 0.9 m width) and bottom bypass (‘motorized gate’; 1.2 m length, 1.3 m width) located on the right bank of the forebay (4-m depth) were opened alternately every other day to allow passage of eels. An angled bar rack (‘trashrack’; 30 mm bar spacing, 20° from the vertical, 20 m length and 3 m height) was located adjacent to the bypasses. Between October and January in 1999–2002, a total of 70 silver eels were captured, fitted with radio tags, and released upstream of the power plant. Untagged eels were caught in a trap below the bypasses in 1999–2001.
(Summarised by: Sam Reynolds)
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