Loch Duart unworried by 'wrasse attack' theory
An employee's 'speculative observation' is not a cause for concern, says Scottish salmon farmer
Scottish salmon farmer Loch Duart says it has “no concerns” over speculation that ballan wrasse used as a natural lice control damaged the eyes of salmon at a marine site used for broodstock.
The possibility was suggested by a member of staff at the farm at Outer Bay (Loch Droighniche), Sutherland, during a visit by the Fish Health Inspectorate, and was reported earlier this week on an aquaculture news website.
The site was inspected after Loch Duart reported elevated mortality at the site due to seal predation, treatment handling, and gill health issues. The mortality was also reported by what the FHI describes as “third party communication”.
Population in good condition
In their report on the visit, the FHI inspector wrote that every pen was inspected and visibility was very clear during the visit. The main population appeared in good condition and exhibited normal swimming behaviour, although a small number of lethargic fish could be observed in the pens.
“These were smaller than the average population and presented eye lesions and snout damage. Sea lice could also be observed on these fish although not in high numbers,” the inspector reported.
The FHI official also wrote that “the site staff believes that the wrasse may be targeting not only the sea lice but also occasionally the eyes of the salmon, causing blindness in a small percentage of the stock.” The inspector also pointed out that feed blocks are available in the pens for the wrasse if they are hungry.
A speculative observation
When asked about the possibility that wrasse had attacked salmon, a Loch Duart spokesperson said: “The suggestion regarding wrasse was an individual’s speculative observation, not a finding of the Fish Health Inspectorate. Inspectors reported that the salmon were in good condition, with normal swimming and excellent feeding responses.
“The site held just 3,164 salmon, representing only 0.09% of Loch Duart’s total stock. We have no concerns and believe reporting should reflect the context proportionately.”
