Session C5: Behaviour of Seaward Migrating Eel at Water Intakes and Low Head Hydropower

• Main Authors: Piper, Adam, Kemp, Dr. Paul, Wright, Dr. Ros
• Format: Text
• Language: unknown
• Published: ScholarWorks@UMass Amherst 2015
• Subjects: Aquaculture and Fisheries; Hydraulic Engineering; Low Head; Anguilla anguilla
• Online Access: https://scholarworks.umass.edu/fishpassage_conference/2015/June23/66

The severe decline of the critically endangered European eel (Anguilla anguilla) has in part been attributed to delayed or blocked seaward migration of escaping adults (silver eels) at river infrastructure. Eels can suffer high rates of injury and mortality at pumps and hydropower turbines and are susceptible to impingement at exclusion screens. For the few downstream guidance and passage solutions trialled for eels, effectiveness is highly variable but generally low. Archimedes screw turbines are considered one of the most ‘fish-friendly’ forms of hydropower. While direct damage and mortality may be lower for Archimedes than other turbines, a two year field study highlighted the influence of a low-head Archimedes facility on the behaviour and downstream passage of silver eel. There has been a historic bias towards physical as opposed to behavioural exclusion or guidance for eel, yet there is increased understanding of the influence of hydrodynamics in the attraction and passage of fish. In a replicated experimental field study employing sub-metre acoustic positioning telemetry at a water intake, we investigated the response of actively migrating adult eel to manipulated flow fields. Eels rarely followed direct routes through the site and displayed avoidance behaviours on encountering constricted flows. Further studies investigated the influence of infrasound as a possible deterrent device within the intake. Findings offer potential to develop behavioural guidance to improve fish passage solutions and enhance traditional physical screening for eel.