Nith District Salmon Fishery Board
River Nith
Nith Catchment Fishery Trust
Nith District Salmon Fishery Board
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The Nith Salmon Smolt Tracking Project is designed to increase our understanding of the Atlantic salmon smolts that live in our river and about what they experience during their migration to the coast.

Though there are gaps in our knowledge about the smolts journey, what we know for sure is that the journey is a very dangerous one and that many of the fish may not make it as far as the river’s estuary, let alone the ocean. Studies on other Scottish rivers have suggested that as many as 40-60% of smolts leaving their tributaries never made it to sea.
So why is the journey so dangerous?

The main threat to the smolts during their journey is predation, until now the young fish have spent their lives hiding, relying on their small size and natural camouflage to help them blend into their surroundings. Now the fish must leave their hiding spots in smaller streams move into the more exposed main river, and to make matters worse for the poor smolts they also begin to turn bright silver! They have effectively gone from hiding in full camouflage to running a marathon in a high visibility onesie!

We believe that the risk of predation is made worse by man-made problems along the route such as the caul in Dumfries town center that funnels the smolts into a choke point. You will most likely have seen for yourself the lines of birds that often wait on the caul for any fish unfortunate enough to swim too close!

The predation risk may also be increased along stretches of the river that have been significantly altered. For example, areas where bankside trees and vegetation have been cleared or where the shape of the river and its banks have been altered. Cover provided by overhanging plants and by naturally undercut banks is very important for the smolts and provides protection from aerial predators, removing this cover leaves them very exposed.

By tracking the smolts through these stages and monitoring their loss rate we hope to discover which threats present the biggest risks, allowing us to prioritize areas for restoration work, hopefully easing the journey for future smolts.

Heron on banks of the Nith

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