Radio receivers (Lotek SRX-DL) are used as fixed stations and will record the identity of individual fish as they pass given points on a river system together with date and time. Further, mobile receivers (Lotek SRX 600) are used as active tracking devices and will record the identity of individual fish as the receiver passes tagged fish in the river together with date, time and GPS coordinates.
Tagged salmon in the South Esk
Up to 15 SRX-DL receivers will be deployed on the river South Esk and these, together with the active tracking receivers and aerial surveys, provide information on the movements of individual tagged fish during their riverine migration. Locations of the receivers can be seen on this map.
Tracking on the South Esk for the first year of the project has been successfully completed. Marine Scotland Science would like to thank all who have helped with the work. The data are currently being analysed and a summary will be provided here in due course.
Tagged salmon in east coast salmon rivers
In addition to the South Esk, fixed receivers have also been deployed in the lower reaches of some other Scottish east coast salmon rivers: the Tay, the North Esk and the Dee (through collaboration with the Dee Fishery Trust). Survey flights have been undertaken to check for the presence of tags in the rivers North and South Esks, Lunan, Bervie, Dee, Don and Tay.
Coloured bars indicate the numbers of tagged fish either detected in each river or taken by coastal fisheries. For any given river, the darker colours indicate the numbers of tagged fish currently in the river while the lighter coloured bars indicate the numbers of fish which have entered the river and have subsequently either returned to the sea, been removed by fisheries or are thought to have regurgitated their tag. Included in the figure is: -