Up to third of wild salmon ‘eaten alive by fish farm lice’

WILD salmon populations are being ravaged by sea lice that escape from nearby fish farms, a new report has found.

Research commissioned by Salmon & Trout Conservation (S&TC) Scotland suggests the parasites are reducing wild salmon and sea trout numbers by up to 29 per cent.

It has prompted calls for the Scottish Government to take action to protect wild fish. Sea lice feed by eating the mucous and skin of fish – which can cause loss of fins, scarring and, if the infestation is large enough, death.

The study, by the Norwegian Institute for Nature Research, found lice levels on wild fish in farm-intensive areas were considerably higher than those in farm-free waters. Examining populations in Norway, Scotland and Ireland, it showed that lice lower stocks of wild adult salmon in such areas by 12 to 29 per cent.

The report said: ‘Scientific studies indicate that salmon farming increases the abundance of salmon lice in the marine habitat and that salmon lice in the most intensively farmed areas have had a negative impact on wild Atlantic salmon and sea trout populations.

‘The effects of salmon lice on Atlantic salmon and sea trout include increased marine mortality, reduced marine growth and, for sea trout, changes in migratory behaviour.’

The Scottish Government has previously maintained that there is ‘no evidence’ in Scotland that sea lice from salmon farming damage wild salmon and sea trout populations.

Andrew Graham-Stewart, director of S&TC Scotland, said the study proved that position was now ‘untenable’. He said: ‘This report substantiates our view that it would be very odd indeed if the Scottish situation was markedly different to elsewhere. We do after all have the same sea lice, which all too often Scottish salmon farm operators are incapable of keeping under control, and the same wild fish.’

A parliamentary inquiry on the impact of salmon farming on wild populations due this year ‘provides a timely opportunity to redress the balance between the drive for growth of the salmon farming industry at all costs, and the need to protect wild fish’, he said.

The group called for new legislation to include culls of farmed fish where sea lice numbers have spiralled.

But Scott Landsburgh, chief executive of the Scottish Salmon Producers’ Organisation, disputed the study’s findings. He said: ‘We are as aware as the S&TCS of the state of wild salmon stocks and have consistently pointed out that scientific research has suggested that any impact of sea lice from farms on wild populations is minimal.

‘It is interesting, however, there is no acknowledgment of the impact of climate change which is undoubtedly having an effect on wild and farmed fish health across the board.’

A Scottish Government spokesman said it would give ‘appropriate consideration’ to the study.

‘We know a number of complex factors, including climate change, are impacting on wild salmon numbers in the north-east Atlantic and that Scotland is one of several countries which have been affected,’ he said.

‘Against this backdrop, it is vital we do everything we can to safeguard wild salmon stocks and we will continue to work with the aquaculture industry, which employs more than 12,000 people in Scotland, to ensure investment and innovation deliver the highest possible environmental standards.’

‘Need to protect wild fish’