The downstream passage of European eels (Anguilla anguilla) through pumping stations is currently a concern in Europe. The EC Eel Regulation (1100/2007) established measures for eel protection from human mediated activities and is enacted through the Eels Regulations (England and Wales) 2009 Statutory Instrument, including requirements for eel passage and states water intakes abstracting greater than 20 m3 a day should be screened. There are 913 pumping stations in England, and yet knowledge of eel damage and mortality during pumping station operation is limited to anecdotal reports. Further, approximately a third of pumping stations in England have a gravity bypass channel but it is currently unknown whether eels pass through them during their downstream migration.
Seven pumps of varying size, design and specification were investigated and the greatest level of mortality was found for the smallest pump with the most blades on the impeller and the highest rotation speed. Eels entrained at sites with ‘fish-friendly’ axial flow pumps also died whereas larger mixed flow pumps that rotated at a slower speed did not kill eels. Key results will be presented, including proportion of immediate and delayed mortality, and the types of internal and external injuries observed. The catchment-wide movements and fine-scale behaviour of downstream migrating silver eels were studied upstream of two pumping stations with a gravity bypass channel using acoustic telemetry. Eels were delayed and performed extensive searching behaviour, which appeared to increase predation, although findings varied between study years with differing flow regimes. Further, tagged eels were detected passing through pumps despite attempts to alter pump operating regimes to maximise the amount of water passing through gravity bypass. Discussion of how the findings are currently being used to help identify the most effective remediation measures for the safe downstream passage of eels through pumping station will be presented.