The following is a December 2024 programme update for Save the Spring, a partnership between the River Dee and Atlantic Salmon Trust, supported by the University of Stirling and UHI Inverness.
Wild Fish Repopulation Update
8 months into our smolt-to-adult supplementation pilot programme, signs continue to be extremely positive. Significant challenges remain, but our team is looking ahead to 2025 with optimism.
Throughout 2024 we’ve been periodically reporting on both elements of Save the Spring: landscape-scale habitat restoration, and wild fish repopulation. For our final update of the year, we wanted to share some key facts and figures about this second part of the programme.
Recap
This spring we selected the River Muick as the initial priority area to pilot the process known as smolt-to-adult supplementation. Wild salmon smolts were safely trapped during their downstream migration in April and were then carefully transported to facilities operated by the University of Stirling Institute of Aquaculture on the West Coast. The fish were then gently transitioned from freshwater to saltwater in the facility’s onshore, closed-containment tanks. Our aim is to raise the fish to maturity before releasing them back into the Muick as adults, in order for them to go on to spawn naturally in the wild, helping to support this fragile population of fish. This approach focuses on wild-hatched juveniles which survive better over the course of their lifecycle than hatchery-born fish.
The team at the University of Stirling
Institute of Aquaculture carry out
periodic grading of the fish. This allows
the optimisation of their care in the
facility according to their growth. The
fish are also assessed for health at this
time.
Key facts & figures
The following infographics give an overview of the status of our fish to-date. For reference, when trapped as smolts in April 2024, the fish were on average around 12cm in length and 18g in weight. For this year’s piloting of the technique, 87 smolts were initially brought into the programme.
What’s in store for 2025
Over the immediate term, the team will continue to carefully monitor the feeding and condition of our fish throughout the colder winter months. Further down the line, we’ll be looking to identify signs of maturation and assessments will be made as to which fish are ready to be returned to the Muick to support wild spawning. Preliminary planning for this activity is now underway, including both the logistics of transporting adult salmon safely back to their river of origin, as well as how we will continue to monitor the movements and behaviour of those fish once released. This is a vitally important piece of work if we are to measure the effectiveness of our actions.
Planning is also taking place with regards to bringing a second cohort of smolts from the Muick into the programme in the spring. We look forward to providing a further update some time in the new year.