Fungus – Saprolegnia

As highlighted in the Fisheries Management Scotland update, there are ongoing reports of severe outbreaks of Saprolegnia in salmon in various rivers in Scotland. There are indications that some strains of Saprolegnia can be a primary pathogen of fish (as opposed to a secondary infection) and that these strains are transferable between rivers.

The identification of more aggressive isolates of Saprolegnia in Scottish rivers is a very worrying development. One of these isolates – ‘phylotype-2’ – which is associated with outbreaks is very pathogenic and kills 100% of Atlantic salmon in experimental challenge studies.

An increased focus on biosecurity for all water users should be a priority, and disinfection of gear before and after use in the Deveron catchment should be undertaken.