Efficacy of a side-mounted vertically oriented bristle pass for improving upstream passage of European eel (Anguilla anguilla) and river lamprey (Lampetra fluviatilis) at an experimental Crump weir

Published source details Kerr J.R., Karageorgopoulos P. & Kemp P.S. (2015) Efficacy of a side-mounted vertically oriented bristle pass for improving upstream passage of European eel (Anguilla anguilla) and river lamprey (Lampetra fluviatilis) at an experimental Crump weir. Ecological Engineering, 85, 121-131.
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This study is summarised as evidence for the following.

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	Install climbing structures for fish Action Link

Install climbing structures for fish

A replicated, controlled study in 2011 in an indoor channel in the UK (Kerr et al. 2015) found that installing vertical bristle fish passes resulted in greater numbers of yellow European eels Anguilla anguilla passing upstream over an experimental weir at high, but not medium or low, water velocities. At high water velocities, the percentage of times eels successfully passed the weir was greater with fish passes installed for small (92%) and large eels (57%) than without fish passes (small eels: 0%, large eels: 5%). The percentage of large eels that successfully passed the weir was also higher with fish passes installed (77%) than without (17%). Successful passage of small and large eels did not differ significantly with and without fish passes installed at medium and low water velocities (see paper for data). A ‘Crump’ weir (34 cm high) was installed in an indoor channel (21 m long, 1.4 m wide, 0.6 m deep). Vertical fish passes (10-mm thick polypropylene boards), each covered with clusters of 24 synthetic bristles (70 mm long, 1.5 mm diameter, spaced 30 mm apart), were installed along both sides of the weir, facing towards the channel wall. In May–July 2011, wild-caught small (82–320 mm long) and large (322–660 mm long) yellow eels were released in the channel during 2–4 trials (8–12 eels/trial) at each of three water velocities (maximum velocity: 'high' = 2.4 m/s, 'medium' = 1.9 m/s, 'low' = 0.8 m/s), with and without fish passes installed. Each trial was carried out at night and lasted 5.5 h. Eel behaviour was monitored with video cameras. Large eels were radio-tagged. 

(Summarised by: Anna Berthinussen)