With the number of European eels in dramatic decline, eel passes like those recently installed by Team Van Oord in two Environment Agency projects have an important role to play in helping to preserve this endangered species.
The Environment Agency estimates that the number of European eels has declined by as much as 95% in the last 25 years.
The video featured above tells the story of the remarkable lifestyle and migration of the ‘critically endangered’ European eel.
Jamie Edmonds, Environmental Manager for Team Van Oord, said: “Restricted access to potential rearing areas is thought to be a significant factor in the decline of the European eel, and there is no doubt that man-made obstructions to migration and dispersion are limiting eel stocks in many parts of the UK.
“The Environment Agency has a programme to identify areas of concern for eel migration and eel passes are installed at these locations. The passes contain bristles, much like an up-turned brush, which mimic grass blades and allow the eels easy passage up and down stream.
“Surveys of the passes have shown them to be well used by eels, and they help to significantly increase eel numbers up stream of previously blocking structures.”
Eel passes have been installed at works recently carried out at two Flume Flow Measuring Stations, at Stanley in Wiltshire and Frenchay on the outskirts of Bristol.
More about the two schemes
Stanley Flume Flow Measuring Station (FMS) is situated on the River Marden approximately 3.5km to the east of Chippenham in Wiltshire, to the north of Stanley Lane bridge.
The site is rural and of low relief, surrounded by arable fields and pasture land with the village of Stanley located on the high ground to the east of the site. The elevation of the site is around 50m above Ordnance Datum (mAOD) based upon historical survey data.
Built in 1968, Stanley FMS is a concrete gauging flume approximately 35.5m in length. The standing wave flume has a maximum design capacity of 56.63m3/s and the flume walls are inclined at 1.5:1.
Team Van Oord was commissioned to: install new Vmax shear stress turf and armor loc erosion protection on both banks upstream of the FMS; undertake repairs and install rip rap erosion protection on both banks downstream of the FMS; and install an eel pass on the left bank.
Frenchay FMS and Weir are situated on the River Frome within a steep and densely wooded ravine located to the south of Frenchay Hospital, on the north-eastern outskirts of Bristol in South Gloucestershire.
The site is suburban, with the residential area of Frenchay located on the high ground to the north, and the landscaped parkland of Oldbury Court to the south. The elevation of the site is around 21m mAOD).
Also built in 1968, Frenchay FMS is a concrete gauging flume approximately 31m in length. The standing wave flume has a maximum design capacity of 57m3/s and the flume walls are inclined at 1.5:1.
Works carried out at the site by Team Van Oord include installing new gabion or rip rap erosion protection on both banks upstream and downstream of the FMS. The project team also installed an eel pass on the right bank, a fish and eel pass in an existing hatch on the right hand side of Frenchay Weir, and carried out masonry repairs to the weir crest and face.
05 May 2017