Endangered fish return to Scottish river after 90% decline

Contributing factors include overfishing, parasites, and also man-made barriers to migration such as hydroelectric dams.

On the river Annan, a weir was constructed in the 1980s to provide water to the Chapelcross nuclear power station, which is currently being decommissioned.

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In 2022, the Nuclear Decommissioning Authority, Nuclear Restoration Services, SEPA and Scottish Water installed an eel pass to allow the endangered Anguilliformes to navigate the barrier and reach the upstream area of the river where they can access 675km of vital habitat to thrive.

Three years on from the eel pass being installed, the Galloway Fisheries Trust has carried out survey work which found baby eels and young adults in multiple locations above the pass, showing it is providing a viable route upstream for the species.  

The eel pass on the River Annan (Image: Scottish Water) Technical team manager at Scottish Water, Euan Innes, said: “It is brilliant that elvers have been found upstream of the weir, it provides us with evidence that the eel pass has been successful and hopefully we will see a lot more eels in the river here as the years go on.

“These eels are very important to freshwater ecology in Scotland and Europe, helping to support other protected species such as osprey and otters. We are not just restoring a single species here, we are attempting to put back a real building block of the ecology of the river system - these survey results are a really positive sign that things are going in the right direction.” 

Andy Gowans, senior fish ecologist at the Scottish Environment Protection Agency (SEPA) said: “SEPA are delighted to learn that eels have been found upstream of Milnby Caul, following the successful installation of the pass in 2022.  
 
“The presence of multiple ages of eels in the Annan provides good evidence that this structure is passable year-on-year, and we look forward to this fish becoming more widespread throughout the river in the future.” 
 
Richard Murray, Chapelcross site director, Nuclear Restoration Services, said: “It’s incredibly rewarding to see the return of European eels upstream of the River Annan following the installation of the eel pass. The recent findings by Galloway Fisheries Trust, showing both baby eels and young adults upstream, are a clear sign that our efforts to support biodiversity are making a real difference. 

An eel being measured (Image: Scottish Water) “Nuclear Restoration Services is proud to have supported this important project, helping to restore natural migration routes of this critically endangered species, contributing to improvements to ecology and overall waterbody status of the River Annan.” 

European eels used for food, including in jellied eels and in sushi.

They begin their life cycle in the ocean before migrating to estuaries or inland where they spend most of their lives before returning to the ocean to spawn and die.

Mating in the wild has never been observed, and attempts to breed the European eel in captivity have proved fruitless.

There are commercial fisheries, which involve catching the young eels and raising them in recirculating pools.

Given that they cannot be bred in captivity, the trade is entirely dependent on wild eels.