Enhancing habitat for threatened fish at Glen Prosen
We recently commissioned the Esk Rivers & Fisheries Trust to determine the current state of juvenile salmon and freshwater invertebrate populations (their food source) at Glen Prosen. Early research is showing that river restoration in the area should benefit fish habitat and numbers over time.
Measuring juvenile salmon and trout before returning them to the river.
The report found that in-stream habitat and water quality was generally good, with few barriers to their movement. Juvenile salmon were found, but they were smaller and fewer in number compared to other sites nearby, likely due to lack of nutrients to support freshwater invertebrates. Juvenile trout were also found.
The main Prosen Water and its tributary burns provide highways for migratory fish in the upper reaches of the River South Esk – which is designated as a Special Area of Conservation for Atlantic salmon.
“With a decrease in Atlantic salmon numbers in the River South Esk over the years, land management measures that improve fish habitat in Glen Prosen could play a key role in protecting and improving the wild salmon and sea trout populations further down river and across the catchment," said Dr Craig MacIntyre from the Esk Rivers & Fisheries Trust.
This work helps us understand what juvenile fish and invertebrates are currently in the area. We can use this to monitor the success of restoration projects in the coming years. It can also help guide us to make more informed decisions about the future of the river.
Stonefly larvae sample from a burn at Glen Prosen.
“This highlights and reinforces the importance and value of our river and burn restoration work in Glen Prosen. It will provide environmental benefits for fish in Glen Prosen and, by supporting larger populations of juvenile fish, potentially the wider River South Esk catchment," said Environment Forester Gareth Ventress.
The report made several management recommendations such as:
- removing non-native conifer trees from the river areas
- planting or regenerating broadleaved riparian trees
Conifer trees can add acidity to the water, while native broadleaved trees help to shade the river and reduce summer temperature. The fallen leaves also provide nutrients to support mayfly larvae and other freshwater invertebrates – the main food source of the juvenile Atlantic salmon and trout.
How were working on restoring the water at Glen Prosen
Our teams have put up almost 14 km of fencing to exclude deer and rabbits from sections of the riverbank to protect young trees.This work has been supported by the Nature Restoration Fund (NRF).
Managing the impacts of deer and other herbivores is an important initial step. The fencing will ensure the successful establishment of young native trees alongside the river.