The Centre for Environment, Fisheries and Aquaculture Science (Cefas), commissioned by the Canal & River Trust, has been looking into the behaviour of migratory fish on the river for a number of years.
Scientists have been monitoring the behaviour of fish and other animals as they use the area around the Tees Barrage for migration and feeding. By specifically monitoring salmon and sea trout as they migrate up the Tees Estuary the study has aimed to assess the main routes and numbers of fish that cross the Barrage at given periods during each year. The study has also highlighted the significant effect seals have on migration and outlined a number of methods that can be trialled to reduce levels of predation.
The research has involved humanely tagging salmon and sea trout with acoustic transmitters and monitoring their movements using a network of receivers in the river up and downstream of the Barrage. This enables fisheries experts to track the movements of the tagged fish, how they interact with seals and observe how they make their way through the Barrage area.
The tagging phase of the study has now been completed and a number of recommendations been made on possible changes to the way in which the Barrage is operated. If successful, the changes should help migratory fish make their way through the Barrage much quicker. Other measures being implemented include monitoring the operation of the White Water Course at different times of day to see how many salmon and sea trout are now using this part of the Barrage to move up and down stream.
We will also be trialling the Navigation Lock, next to the Barrage, to give fish another route particularly when seal numbers build-up in front of the Barrage gates. A feasibility study is also underway to look at the practicalities of installing seal-proof steel cages at the mouth of the existing Denil Fish Pass. We will ask the Environment Agency for a continuation of provisional fish pass approval while we put these changes into practice.
The study is of national importance as currently there is very little information available on the migration and movement of salmon and sea trout particularly on the Tees. The detailed findings of this project will help to give an insight into other rivers elsewhere in the country such as the Wear and the Tyne.
Jonathan Hart-Woods, environment manager for the Canal & River Trust said: “People may forget that the Tees is a river in recovery from the heavy industries of the previous century and, not so long ago, there weren't many salmon or sea trout entering the Tees Estuary because of poor water quality and pollution.
“The Tees Barrage has a major role to play in facilitating the movement of migratory fish upstream as quickly as possible. This study has given us the information we now need to make these improvements and to target future resources and research.
“We want to continue to work on building our understanding of the river and the Barrage and help to improve the ecology of the River Tees by working with all the organisations and interest groups who have the same goals”.