Eel Pass Provides Helping Hand to Critically-Endangered Species

09 September 2025

Upstream eels

Young European eels have officially been recorded in upstream River Annan following the installation of an eel pass in 2022.

A critically-endangered species of eel has officially returned to upstream River Annan thanks to an eel pass installed at Milnby Weir in 2022. 
  
The first river survey in three years has provided evidence that young European Eels are now populating the upper Annan, following installation of the pass. 
  
The partnership environmental project, involving the Nuclear Decommissioning Authority, Nuclear Restoration Services, SEPA and Scottish Water, aimed to provide the young eels with a route to bypass the weir and reach the upstream area of the river where they can access 675km of vital habitat to thrive. 
  
The weir acts as a barrier preventing the elvers from reaching the upper part of the river, with the current structure dating from the 1980s to provide water to the Chapelcross nuclear power station, which is currently undergoing decommissioning.  
 
Now, 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.  
 
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.” 
  
He added: “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.” 
  
Since the 1970s, the population of European Eels in is estimated to have fallen by around 90%, leading to it being regarded as critically endangered. The eels spend much of their adult lives in our rivers, before travelling to the Sargasso Sea to spawn - the young eels are then carried back towards Europe on the currents and the cycle starts over again. 
  
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. 
  
“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.” 
The weir on the River Annan was preventing eels from reaching the upstream area of the catchment

Survey results

Baby eels and young adults were found in multiple locations above the weir, providing evidence that the eel pass has been successful.