Wild salmon have returned to a Perthshire river that had been drained for more than 60 years to boost hydro-power generation.
Water from an upstream dam on the River Garry was released in 2017 and a constant flow has been maintained ever since.
Salmon eggs taken from brood stock in hatcheries were used to kick-start the fish population, with more than two million eggs released in the river and its tributaries over the past seven years.
Genetic studies carried out by researchers at the University of the Highlands and Islands (UHI) in Inverness have revealed that fish stocked from eggs have thrived, and they’ve been joined – and are now outnumbered – by wild Atlantic salmon.
Dr Victoria Pritchard, UHI senior researcher, said: “In the first few years in the areas where the fish were stocked, we only found stocked juvenile salmon, but in the areas downstream we found a mix of stocked juveniles and also wild spawned juveniles.
“In the fourth year we found wild spawned fish right up to the top of the river, and this was quite a surprise. So that implies that there are wild populations of salmon breeding naturally all the way up the river.”
Dr David Summers of the Tay District Salmon Fisheries Board added: “We’ve now got significant numbers of returning wild fish spawning in the main River Garry, and they are now the majority of the fish in the river.
“Salmon populations are declining everywhere, but if we can show, as we are, that this is a successful restoration project then it shows there is hope for salmon, both here and more generally.”
The restoration project relied on engineering work bv SSE Renewables.
SSE’s Andy Jacobs said: “Previously from that dam there was no facility to release a continuous flow, so what our team of engineers had to do was to retro-fit a system to allow down-stream flow.
“What you will always see is a minimum flow, and with weather conditions that will increase and decrease.”
The genetic monitoring of the salmon will continue, as will the release of eggs in the Garry’s tributaries.
It’s recognised that while the restoration of the river as a breeding ground has been successful, the Atlantic salmon remains under serious threat.
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