Elver passes (or ladders) are commonly installed to facilitate the upstream movement of juvenile eels at barriers to their migration. However, there is conflicting guidance on the positioning and hydrodynamic features required at pass entrances to allow eels to effectively locate this route of passage (i.e. to optimise attraction efficiency).

This study aimed to assess the efficacy of manipulating hydrodynamics to improve attraction at elver passes, and explore the relationship between pass position and relative passage efficiency at a large intertidal weir. A combined field and flume based approach was adopted which identified clear behavioural responses to water velocity and turbulence. More elvers were attracted to pass entrances characterised by plunging rather than stream flow. This information will improve our ability to mitigate the impact of barriers on upstream juvenile eel migration. This work was funded by the Environment Agency (England).

Publications:

Piper, A.T., Wright, R.M. & Kemp, P.S. (2012). The influence of attraction flow on upstream passage of European eel (Anguilla anguilla) at intertidal barriers. Ecological Engineering 44: 329-336.

People:

Dr Adam Piper

Prof Paul Kemp