PLANS for a massive expansion of the fish farming industry to include cod, halibut and haddock could lead to a serious increase in pollution of Scottish sea lochs and rivers, according to a new report.
The Scotsman has learned that cod farming would bring about at least 50 per cent more discharge and waste than that generated by salmon farming per tonne of produce.
Such waste is discharged directly into the surrounding waters of the sea lochs, and conservationists say it threatens the fragile marine ecosystems where the farms are located.
With little prospect of a sustained recovery of north-east Atlantic and North Sea cod stocks, which has led to a 45 per cent European quota cut, cod farming has almost overnight become economically viable.
A previously unseen report produced for the Convention for the Protection of the Marine Environment of the North East Atlantic reveals the true extent of the ecological impact that cod aquaculture would have.
Currently, for every tonne of salmon that is farmed, 48.2kg discharge of nutrient nitrogen in the form of faecal waste and uneaten feed pellets goes directly into the surrounding water. Cod farming, however, would produce 72.3kg of such discharge for every tonne farmed - a 50 per cent rise.
According to the industry body Scottish Quality Salmon, 2002 was the biggest year for salmon farming in Scotland so far, with 150,000 tonnes produced. As a consequence, 7,230,000kg of waste was discharged into the waters surrounding the farms.
That figure would leap to 10,845,000kg of waste if salmon production was switched to cod. Rich in nitrogen, nutrients in the waste have been blamed for causing harmful algal blooms in coastal waters.
Under severe conditions, serious depletion of oxygen levels can occur, and be associated with killing fish and marine fauna. Major farmed fish producers have so far remained tight-lipped about planned growth, but sources predict the Scottish industry aims to produce 30,000 tonnes of cod and 10,000 tonnes of other fin fish annually within ten years.
By 2030, farmed white fish production could be greater than the salmon aquaculture industry’s current yearly production.
The new partnership deal for government, agreed at the beginning of last month by Labour and the Liberal Democrats, promised to cut the number of agencies regulating the industry. The agreement said: "We will support the growth of an aquaculture industry in salmon, other fin fish and shellfish that is sustainable, diverse and competitive."
The Scottish Environment Protection Agency (SEPA), has also said it supports the diversification of fish farming into species such as cod, haddock and halibut.
But figures released last month showed the number of incidents in which fish farms polluted rivers and lochs have doubled in the past year - and campaigners say the switch from salmon farming to cod is no easy solution. Since 1996 there have been a total of 51 pollution incidents at fish farms. In every year until 2002, the number of incidents has been between five and seven. But in 2002 - 2003 it leaped to 13.
Don Staniford, of the salmon farm protest group, and a leading critic of the fish farm industry, said: "Diversification into cod, halibut and haddock farming can only compound the current crisis. Cod farming, for example, represents a double whammy in terms of both increased discharges of sewage wastes into the marine environment and a bigger appetite for precious wild fisheries resources as feed.
"Such a wasteful form of fish farming is inherently unsustainable and represents a threat not only to wild fisheries but also to the Scottish marine environment. Diversification is merely a euphemism for increasing pollution."
Duncan McLaren, chief executive with Friends of the Earth Scotland, said: "Worryingly, this new research shows that plans to expand cod farming will make Scotland’s fish farming industry even more polluting and even less sustainable.
"Combined with industry plans to expand cod farming, proposals by the Executive to reduce the regulation of fish farms will do absolutely nothing to protect Scotland’s environment or move the industry to a sustainable footing."
A spokesman for SEPA said: "We work out what level of aquaculture activity the receiving environments can take, and then establish a limit which is based on a large number of factors. To say that cod farming would be 50 per cent more polluting would only be correct if you were talking about producing comparable biomasses.
"That is not how SEPA arrives at decisions and we do not necessarily consent the same amount of fish production for each site. We do take into account the different environmental impact that farming different species might have."