One of the central goals of this project is to determine the migration routes of salmon and sea trout and how these routes relate the physical marine environment. This information should be provided by tracking the movement of these fish from the rivers Dee, Don and Ythan, each of which are located within 10km of the EOWDC and have fisheries of economic value.
Juvenile salmon and sea trout leave these rivers each spring. Salmon head to their feeding grounds in the North Atlantic and Greenland whilst sea trout are believed to reside in the coastal habitat. However, there is little knowledge on pathways and how salmon and sea trout behave out with these rivers.
The project will involve fitting 300 juvenile salmon and 100 sea trout migrants with acoustic tags as they exit the rivers and navigate up the North-East coast out to sea. From 2018, 91 receivers will be deployed in the estuarine and near-shore environment to determine the direction of travel of salmon and sea trout. These will be redeployed in subsequent years to refine the pathways of these fish, creating a picture of dispersal zones from rivers.
Information on movements, dispersal and knowledge of currents will be fed into the Scottish Shelf Model - an existing hydrodynamic model developed by Marine Scotland Science - to determine the pathways salmon and sea trout take and what influences this.
This project will provide valuable information for other offshore developments in terms of where fish may be encountered, the scale of such interactions and whether these fish follow narrow migration pathways or wider dispersal areas, thus filling the existing knowledge gap on how salmon and sea trout migration and behaviour away from rivers.
Mark Bilsby, River Director, River Dee Trust, said: “We are looking forward to this exciting project as it will provide a unique insight into how the young salmon and sea trout fare as they leave the rivers around Aberdeen and embark on their journey as far away as the west coast of Greenland. At the moment, we know more about them on the high seas than we do in our coastal waters so by understanding this first part of the journey we can help ensure as many survive as possible.
Lorraine Hawkins, Trust Manager, River Dee Trust, said: “This acoustic technology will help us to understand where salmon go, what guides their migration and, in the future, what determines whether they will return to their home river to spawn. Working with tracking experts in Marine Scotland Science, we will piece together the picture of how salmon and sea trout movements are affected by ocean currents to show the journeys these fish take in our coastal waters.”