Workers have used electric probes to zap rare eels – to make way for the Borders Railway.
The rare snake-like critters were stunned with special electrodes to allow work on the major new line which will link the Capital and Tweedbank.
More than 70 juvenile river and brook lampreys – a fish known for its trademark toothed, funnel-like sucking mouth – were shifted from Gala Water, just north of Fountainhall, earlier this month to an undisclosed upstream location near Edinburgh.
A spokesman for the project said they were “delighted a solution was found to protect lampreys from our works”.
He revealed specialist workers resorted to electrofishing to capture the lampreys, which can grow up to one metre long.
The method involves using electricity delivered from two electrodes to stun the fish, making it easier to catch them with a net.
No permanent harm is caused to the creature using the technique, which was carried out by two surveyors.
Hundreds more could yet be moved via the electro-stun tactic, as contractors are investigating 30 other sites known to harbour the protected eels.
Network Rail senior project manager Hugh Wark, who is responsible for the project, said: “Lamprey are a protected species in the Gala Water and we want to ensure that the effects of our work on them is minimised.
“We take our commitment to the local environment very seriously and we are delighted that a solution was found to protect lampreys from our works. We will continue to work with specialist ecologists to ensure that all wildlife species along the line of the route are protected from the impacts of our works.”
He said relocation of the lampreys to an alternative habitat is part of Network Rail’s commitment to protecting local ecology during the £300 million project.
The electrofishing was carried by contractor Eco-Fish Consultants under a licence issued by Marine Scotland.
Eco-Fish director Richard McMullan said the lamprey was a parasitic species, adding: “They attach on to the side of salmon and suck their blood.”
The lamprey is not the only native animal that Network Rail has gone to great lengths and expense to save.
Artificial badger setts have been created, with £10,000 set aside to create alternative accommodation for the nocturnal hunters. Owls, bats and otters have also been protected.