Lighting up life for salmon in River Exe

Westcountry Rivers Trust is set to tackle the problem of overshading on the Little Exe this winter. Funding from the Exmoor Sustainable Development Fund is being used to carry out coppicing to increase light into shallow areas as part of the river restoration project to improve salmon numbers in the river.

Salmon numbers in the river have been declining for a number of years. It is thought that overshading by trees and vegetation which restricts light into the river is contributing to the decline.

Excessive shading in the lower section of the Little Exe may be affecting the number of salmon and trout fry in this area. Research suggests that tunnelled sections greater than 100m in length rarely support more than 40% of the juvenile salmon numbers observed in more open stretches. With restricted sunlight reaching the river corridor, the plants communities within the river and along the riverbank are unable to grow. These plant communities are an important food supply for the river invertebrates which in turn provide the food for juvenile salmon and trout. Root systems of bankside plants also offer protection from erosion.

After the Second World War the practice of coppicing for charcoal or gunpowder ceased and so the coppiced trees grew into multi-stemmed forms which cast heavy shade onto the rivers. As a result some sections of the Little Exe have tunnelled vegetation. Westcountry Rivers Trust have begun work this winter with local contractors to introduce more light into the shallow riffle areas. The coppicing work will be carried out in accordance with the Environment Agencies ‘Code of Good Practice for Bankside Coppicing’. Care and consideration will be given to other species that live along the river corridor.

Commenting on the restoration programme, Dr Neasa Mc Donnell, the Trust’s Project Officer for the Exe, said, “Electrofishing surveys carried out by the Trust in the summer have shown lower than expected salmonid fry numbers in overshaded sections of the river. The coppicing should boost macroinvertebrate communities in these sections, increasing the food supply for salmon and trout fry, and ultimately increasing salmon numbers”.

She continued, “We are grateful to Exmoor National Park Authority for providing this funding to enable us to carry out this important work”.