Case study:Pearls in Peril LIFE+ GB Project - River Ehen
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- 1 Project overview
- 2 Image gallery
- 3 Catchment and subcatchment
- 4 Site
- 5 Project background
- 6 Reasons for river restoration
- 7 Measures
- 8 Monitoring
- 9 Additional documents and videos
- 10 Additional links and references
- 11 Supplementary Information
|Project web site||http://www.pearlsinperil.org.uk/|
|Themes||Fisheries, Habitat and biodiversity, Hydromorphology, Water quality|
|Main contact forename||Jackie|
|Main contact surname||Webley|
|Main contact user ID||User:Pearlsinperil|
|Contact organisation||Scottish Natural Heritage|
|Contact organisation web site||http://http://www.snh.gov.uk/protecting-scotlands-nature/protected-species/life-projects/pearls-in-peril/|
|Partner organisations||West Cumbria Rivers Trust, Environment Agency, Lake District National Park, United Utilities|
|Parent multi-site project|
| This is a parent project
encompassing the following
The River Ehen, supports the largest viable population of pearl mussels left in England, estimated at between 350,000 and 500,000 individuals. The Ehen is the most important river in England for freshwater pearl mussels, both biogeographically and for its size and population structure. 13km of the main River Ehen, from the outlet of Ennerdale Water, to the confluence of the River Keekle in Cleator Moor are designated as protected sites for both pearl mussels and Atlantic Salmon.
Pearls in Peril has delivered actions that work to reduce diffuse pollution, siltation and erosion and aim to improve water quality to safeguard the future of the River Ehen freshwater pearl mussel population.
The project has produced a river wide Conservation Management Plan that, for the first time, brought together stakeholders across the catchment to identify key issues and priorities. Directed by the Management Plan and supported by project partners the project has completed over 240m of willow spiling, fenced livestock from 5km of riverbank, provided alternative livestock waterings and planted over 7000 trees. Five sites, covering 350m of riverbank, have been restored using green engineering techniques including bank re-profiling, tree planting, willow spiling, and fencing. In-river obstructions causing erosion and scour have been removed and brash bundles have been used to encourage natural river bank restoration. Gateways and heavily poached stock crossings have been gravelled and the project has removed 60 tonnes of rubble from riverbank. Artificial bankside encystment of Atlantic Salmon was also carried out.
Volunteers have undertaken incredible amounts of work including hedge laying, making brash bundles, installing leaky dams, creating new wetland areas and tree planting.
Monitoring surveys and results
Monitoring work has been undertaken including sonde data collection, freshwater pearl mussel survey and electro-fishing. On the River Ehen Atlantic salmon are the preferred host fish for as part of the freshwater pearl mussel lifecycle.
Successful encystment occurred in August 2013 (27 salmon fry), August 2014 (76 salmon fry) and September 2015 (41 salmon fry). Levels of encystment, natural and artificial, were monitored from 2010 to 2016. In 2010 1 site was sampled and 34 out of 39 salmon showed signs of encystment; in 2013 5 sites were sampled and 24 out of 32 salmon were encysted; in 2014 8 sites were sampled and 25 out of 51 salmon were encysted; in 2015 7 sites were sampled and 15 out of 21 salmon showed encystment; and in 2016 7 sites were sampled and 18 out of 21 salmon were encysted.
Pearls in Peril is supported on the River Ehen by a Technical Steering Group. This Group brings together key stakeholders in the catchment and shares information on other activities and projects being undertaken. Through this group many opportunities have been realised and additional benefits gained. This approach is worth considering for future projects on rivers where there are many interested stakeholders.
Catchment and subcatchment
Cost for project phases
Reasons for river restoration
Hydromorphological quality elements
Biological quality elements
Physico-chemical quality elements
Additional documents and videos