Project Deveron

The number of Atlantic salmon returning to the Deveron has followed the current national trend and has crashed over the last 10 years. Despite the cessation of all commercial netting on the coast by the Scottish Government and the adoption of catch and release by anglers (currently over 93%) the number of salmon caught by rod & line in the Deveron has declined by 57%. Furthermore, 3 of the lowest annual catches on record have occurred in the last 7 years. It is vital now, more than ever, to gain a better understanding of the numbers of salmon smolts leaving the river and numbers of salmon and sea trout returning to the river to spawn.

Project Deveron is a partnership between the Deveron, Bogie and Isla Rivers Charitable Trust, The Atlantic Salmon Trust , and Marine Scotland Science . The project will develop and apply electronic fish detecting systems to monitor juvenile and adult salmon in the River Deveron and provide information for designing management locally and nationally. The project is an extension to the Scottish Salmon Counter Network, part of a package of measures to support salmon conservation using funding announced by the Cabinet Secretary in October 2021.The project will apply two detecting systems, an acoustic camera to produce images of fish moving upstream, and a series of cross-river arrays for registering the passage of salmon tagged with miniature passive integrated transponders (PITs). Trials have been conducted on the lower Deveron this summer to find a suitable location for permanent installation of the acoustic camera, which requires an appropriate riverbed profile. The ultimate goal from applying this apparatus is to provide a count of Atlantic Salmon and Sea Trout entering the river Deveron together with associated methods to differentiate between the species. Counts will contribute to national assessment of salmon conservation status and local monitoring of stocks.

Alongside the new counter, a series of PIT tag detecting arrays have been installed in the Allt Deveron in the Cabrach and at Avochie Estate. These arrays will detect any fish with a PIT tag and will allow us to monitor mortality of smolts on their downstream migration, subsequent survival at sea, and also to determine which individuals make it back as adults from their marine migration. The PIT tags used forthis work have three significant advantages over the acoustic tags that we have previously used for smolt tagging: PIT tags do not have a battery which means they will work indefinitely; they are much smaller so can be inserted with minimal stress to the fish and they are far cheaper, so many more fish can be tagged. Up to 2000 salmon parr will be tagged each Autumn from the Allt Deveron and Blackwater and their progress downstream will then be logged on the Cabrach and Avochie arrays before they head to sea each spring. If and when they return after a year or more at sea, they will be logged again as they migrate upstream past the arrays to their spawning grounds. It will be possible to relate down-river and marine survival to size and condition of smolts.

This information will allow us to optimise management actions in freshwater as measures to improve overall survival of salmon. The combination of the full river count and the smolt and marine survival estimateswill help all project partners to understand where the losses of salmon occur and what management measures can be implemented to protect stocks in the future.