A moderately large fish farm will dump the same amount of sewage as a town twice the size of Oban, an expert claims
The National Trust for Scotland (NTS) has called on the country’s fish farming sector to fix its pollution problems before contemplating further expansion.
Its experts say that Scotland has the potential to support a successful aquaculture sector, but only if we effectively manage issues of effluent discharge, disease and chemical pollution.
It says that as a country, our food and drink products trade on associations with a pristine and beautiful natural environment, and we can’t risk undermining this for short-term gain.
Scottish farmed salmon is produced in open cages, anchored in coastal areas of the west coast and the northern isles.
There is currently a moratorium on fish farming on the north and east coasts to protect salmon rivers there. The particular problems for the Scottish industry are the prevalence of sealice, which have a damaging effect on farmed fish, but also on wild salmon and sea trout.
The chemical treatments used to tackle these infestations can cause damage to wild species, including crab, lobster and langoustine, themselves economically important.
NTS senior nature conservation advisor, Dr Richard Luxmoore, said: “The Scottish industry last year lost more than a million fish to sea lice infestations. The impacts on wild fish are harder to measure, but they add to other factors leading to the collapse of wild salmon and sea trout stocks, for instance on the River Awe.
“Remarkably, there is no single government body with responsibility for the health of our wild fish.”
A further problem is the waste food and untreated faeces discharged from fish farms.
Luxmoore said: “A moderately large fish farm will dump the same amount of sewage as a town twice the size of Oban, and, unlike human sewage, it is entirely untreated.”
An inquiry carried out by a Holyrood committee recently said it was “deeply concerned” about the environmental impact of salmon farming, and concluded the status quo was “not an option”.
It was not convinced the sector is being regulated effectively, and made it clear that this needs to be addressed urgently because further expansion must be on an environmentally sustainable basis.
The Scottish Wildlife Trust was among the charities which gave evidence to the Scottish Parliament inquiry.
It stated: “It is clear that the salmon farming industry has been allowed to grow too rapidly without full consideration of the impact it has on the health of the marine environment.”
