Salmon affected have a characteristic red-spotted rash on their underbelly and may appear lethargic or moribund. In the past few weeks, suspected cases have also been reported in Denmark, Norway and Scotland.
Pink salmon are native to the Pacific Ocean. From stocking programs in Russia in the 1960s they have spread to Northern Europe, and in 2017 male and female pink salmon were spotted in the River Ness in the Highlands of Scotland. And now, two years later, camera images suggest that their spawn has returned.
Anglers will be banned from taking their catch home on more than 100 rivers in Scotland this year - as wild salmon stocks reach 'crisis point'.