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Save the Spring – May 2024 Update

The following is a May 2024 programme update for Save the Spring, a partnership between the River Dee and Atlantic Salmon Trust, supported by the University of Stirling and University of Highlands & Islands, Inverness.

Smolts enter the programme

The arrival of 87 wild Atlantic salmon smolts into the programme, safely captured from the River Muick priority area, marks the beginning of our smolt-to-adult supplementation pilot year.

In our April 2024 update we announced that the first wild salmon smolts (juveniles on their downstream migration to sea) had entered the wild fish repopulation programme, and this update is about sharing more of the exciting detail around this part of Save the Spring.

As a reminder, Save the Spring takes a combined strategic approach to the restoration of the River Dee’s wild Atlantic salmon population, focusing both on catchment-scale habitat restoration work to build climate resilience for the future, and giving the wild salmon population an immediate and careful helping hand through wild fish repopulation.

Our wild fish repopulation focuses on maximising the number of salmon spawning in the wild, minimising the negative selection effects which can arise from more traditional hatchery practices, and allowing the river to produce as many wild-hatched juveniles as possible. Smolt-to-adult supplementation (S2A) is the key focus for us at present, aiming to capture wild Atlantic salmon smolts from strategically identified tributaries in the Dee catchment where habitat restoration is also occurring. These fish will then be raised to adulthood and then released back into the wild at the same location of their capture, to spawn naturally.

Smolt-to-adult supplementation (S2A)
Wild Atlantic salmon smolts are safely captured from priority areas in the catchment to be reared in captivity
until they are mature adult salmon. These adults will be released back into the wild to spawn naturally.

These fish were all weighed, measured, and had a small PIT (passive integrated transponder) tag inserted. This information will allow us to monitor individual fish as they grow in captivity. Additionally, each fish has been genetically sampled to allow us to measure the success of the programme by tracing the lineage of future juvenile and adult fish
sampled from the wild, matching them up to fish from the S2A programme.

After being PIT tagged, the smolts were then carefully transported to the University of Stirling Institute of Aquaculture’s Marine Environmental Research Laboratory (MERL) in Machrihanish on the West Coast where we aim to rear them to maturity with a view to reintroduction back into the wild to spawn. Upon their arrival at the facility, the smolts were gently transitioned from freshwater to saltwater over several days and they are now feeding well which is hugely encouraging to the team.

The news from our small set of 9 kelts (post-spawn wild adult salmon), captured from the upper main stem of the Dee earlier this year and taken into the University of Stirling Institute of Aquaculture facility near Stirling, has not been so positive, unfortunately. We are very sad to report the loss of this group of fish. Losses of wild post-spawn Atlantic salmon are known to be high and, despite the best efforts of our team, it seems that the combination of naturally occurring fungal spores – which are ever-present in freshwater – and the weakened state of the fish after spawning in the wild, has not on this occasion enabled us to rear them back to health successfully. The team will now regroup and consider options to try with wild post-spawn kelts again this winter.

The smolts are carefully introduced to their new home and acclimatised to saltwater.

It is worth noting just how many passionate individuals are working hard together to make the wild fish repopulation programme a success, both from the project partners at the River Dee and Atlantic Salmon Trust, through to the dedicated fish care team from the University of Stirling. All of us are motivated by a desire to do the best we can to preserve the River Dee’s unique wild Atlantic salmon, maintaining their genetic adaptability and giving them the best chance at a long-term, sustainable future. The S2A and kelt reconditioning programmes are both highly novel, come with many challenges and we are all learning as we go, drawing on the best available science, veterinary and animal husbandry techniques to inform our decision making, and acting with as much care and sensitivity to the fish as possible.

With the successful entry into the programme of the first set of smolts and encouraging feeding behaviour recorded (which can be seen in the video below), we are now looking ahead with a great deal of positivity, albeit we are in the very early part of this process too.

Our May 2024 Update can also be read and downloaded as a PDF.

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