Smolt Tagging and Tracking Project

Ensuring as many smolts as possible get to sea, is a major part of our work on the Dee

The production of smolts is central to the work of the Dee Board and Trust. Recent poor seasons have given everyone cause for concern, particularly the fate of our smolts as they begin their long journey from the river through the harbour and estuary to the open sea. This early part of the smolts’ journey has been shown to result in high mortality rates in other systems and it is crucial we discover what is happening on our own doorstep. There are many theories about the condition of the Dee juvenile population and a new project will produce hard facts and inform decision making.

One of the ways in which we monitor numbers is through smolt traps. We have had smolt and adult fish traps, which are owned and operated by Marine Scotland Science, since the 1960s. These traps  on the Girnock and Baddoch have helped us monitor fish production in the upper river.  

While we are satisfied that the river is producing the right number of smolts, the existing traps on the upper river have recently shown good numbers in 2015, but we need to expand our efforts to ensure our information includes the middle and lower river. To that end, we have two new facilities on the Beltie and Sheeoch Burns. These will enable us to determine smolt production and record numbers of returning adult fish. Finally, we will be tagging the smolts we trap next year and will be able to track their movements and develop our understanding of the effects and levels of predation and other factors which impact on their survival. The project has two key elements.

New Smolt Traps

Rotary screw traps to catch smolts will be deployed at the bottom of both the Sheeoch and Beltie burns. A vaki fish counter will also be installed on the Sheeoch, which, along with the vaki counter operated by the Middle Dee Project on the Beltie, to count the number of adults returning. This will help us to recognise if and when low adult returns start to affect juvenile production.

Smolt Tracking

Smolt tagging and tracking will be undertaken as a three-year study, starting in 2016, which will report each year. Smolts caught in the traps on the Beltie and Sheeoch burn will be fitted with an acoustic tag, which sends out an audible ‘ping’ every few seconds. To detect these tagged fish, hydrophones will be anchored into the river bed and through the Harbour area.

From this, we will be able to produce a much clearer picture of the smolts near-shore movements and coastal migration routes. We will also have more detailed information on the timing of the run and when they leave the monitored tributaries. The project will also give us an accurate picture of smolt mortality from exiting the tributary to exiting the Harbour and where and when predation has the greatest impact. Identifying these factors will support management decisions to help reduce predation risk.

Keep an eye on Latest News for project updates

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