DRIVERS OF MOVEMENT AND SOCIAL BEHAVIOUR OF EUROPEAN EELS IN UK RESERVOIRS

Large, disconnected waterbodies such as drinking water reservoirs hold significant stocks of European eel but there is often no feasible migration route by which adult eels can escape to undertake their seaward spawning migration. The Eels (England and Wales) Regulations 2009 provide strong drivers to protect eel from damage and mortality at water abstraction points, and to develop effective means (e.g., fish passes and trap and transport programmes) to enhance escapement of reservoir eels to the sea. However, little is currently known about the movement patterns or social behaviour of adult eels in reservoirs.

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Greater understanding of eel responses to environmental cues in large lentic waterbodies will help inform the management and conservation of such populations, for example, by identifying screening priorities at pumps, enhancing trap and transport schemes, and informing adaptive management measures.

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As part of this project acoustic telemetry is being used to determine the distribution, movement patterns and residency characteristics of adult eels within a large reservoir. Eel data will be analysed in relation to concurrent environmental and physiological data to quantify the relative influence of these factors on eel movement, and used to develop predictive models to enable forecasting of eel movement and behaviour under a range of management scenarios.

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In addition, field experiments are being conducted to test the potential of flow manipulation to deflect eel on their approach to pumping stations. Acoustic positioning telemetry and sonar imaging technology are employed to monitor the fine scale behaviour of adult eel on the approach to flow sources. Eel swim paths generated from the positioning data will be analysed in relation to mapped flow fields to quantify how eels respond and determine if this approach has potential to work in other real-world situations to guide eels towards safe passage routes.