The River Ehen in West Cumbria supports the largest population of mussels in England and as a result it is designated as a Special Area of Conservation (SAC) and Site of Special Scientific Interest (SSSI). Atlantic salmon is also a qualifying feature of the SAC.
The SSSI has been assessed by Natural England as being in “unfavourable declining” condition due to insufficient freshwater mussel recruitment, making the current population unsustainable. Some juvenile mussels are present, but the current demography of the population is not likely to support long-term sustainability.
Assessment of Atlantic salmon egg deposition in the River Ehen by the Environment Agency (2018), indicates that the salmon stock is “probably at risk” and is likely to continue to be for the next five years. Some of the reasons for the decline of both species include habitat degradation from nutrient run-off, excess silt covering the riverbed and an unfavourable flow regime.
See the attached pages for more information on freshwater mussels and Atlantic salmon…