Using a large-scale open-channel flume, the swimming ability and behaviour of individual adult European eel Anguilla anguilla and river lamprey Lampetra fluviatilis, species that exhibit anguilliform locomotion, were quantified under complex hydraulic conditions created by a 0·2–0·3 m high under- or overshot weir during four discharge regimes. Fishes were allowed to approach the weirs from both up- and downstream. All fishes passed the undershot weir, independent of discharge and direction of movement, and under high flow (mean ±s.e. 194·63 ± 6·48 l s−1) moved upstream against velocities that ranged between 1·75 and 2·12 m s−1, suggesting greater maximum swimming capability than previously reported. In comparison, passage efficiency during upstream movement was lower for the overshot weir for both L. fluviatilis and A. anguilla. Downstream moving A. anguilla took longer to pass the over- than undershot weir. This study describes a methodology to attain realistic measures of swimming ability and behavioural performance required to develop multispecies fish passage criteria.
If you can't find a tool you're looking for, please click the link at the top of the page to "Go to old article view". Alternatively, view our Knowledge Base articles for additional help. Your feedback is important to us, so please let us know if you have comments or ideas for improvement.