The first fillets of Scottish-farmed cod have gone on sale around the UK. Retailers say it could guarantee stocks of a favoured fish and revolutionise the fishing industry - but environmental groups say lessons must be learned from the problems affecting farmed salmon.

BBC consumer affairs correspondent Nicola Carslaw reports

It is a single-track drive to Ardtoe, a remote research station at the water's edge on the west coast of the Scottish Highlands.

This sandy shoreline at the foot of snow-capped hills is home to the Sea Fish Industry Authority - Seafish, for short.

Laboratories

In laboratories alongside circular, land-based tanks full of fish at different stages of their development, work is under way to try to meet the demand of UK consumers for plentiful supplies of sea-food.

Currently, it's cod that's under the microscope. With funding from development agency Highlands and Islands Enterprise and companies such as Marks and Spencer, they're investigating whether it is viable to farm the UK's favourite fish.

They have already had some success. M&S liked what they tasted and have just put the first 10 tonnes of farmed cod on sale in some of their stores.

Now. it's up to shoppers. Last year, we bought 170,000 tonnes of wild cod.

But the problem is our fishing waters cannot meet such a huge demand and most of it has to be imported from places such as Iceland and Norway. So, farming it seems an ideal solution.

The Head of Seafish Aquaculture at Ardtoe, Malcolm Gillespie, says fishermen's quotas have been cut drastically to preserve cod stocks in the North Sea, and the Irish Sea and cod farming will help meet future demand without the need to increase imports.

"As consumers become more health-conscious and recognise the benefits of fish, there's every chance the demand will be increased still further and farming is a way of relieving the pressure on wild stocks."

Deep concerns

But campaign groups say they have deep concerns. Friends of the Earth is opposed to what it calls the privatisation of fish.

It fears that resources that belong to us all are increasingly being controlled by multi-national companies.

Its spokesman in Scotland, Don Staniford, says lessons must be learned from salmon farms.

He is worried about disease spreading among intensively farmed fish grown in crowded sea-cages.

"Over the last year, three-quarters of the Scottish salmon industry has been quarantined due to infectious disease and four million farmed salmon slaughtered," he says.

Additives

He points out that farmed fish is not labelled as such and fails to tell us what chemical additives it contains.

For example, the M&S fillets are marked simply "West Coast Scottish Cod."

He accuses supermarkets of duping consumers into believing they're buying naturally harvested products.

In response, M&S says it will consult customers - which may well result in labelling the fillets as farmed.

Meanwhile, the young fish from Ardtoe are transported to the UK's first commercial cod farm on the shore of Loch Striven, west of Glasgow. They are grown in large concrete tanks with pumps to ensure there is always fresh water.

Healthy

The cod are fed on pellets made from fish meal and fish oil. Waste is discharged into the loch.

So far, in spite of the fact that there can be 1,000 cod to a tank, there has been no evidence of disease.

Cod seems to be more resistent to illness than salmon - and that is encouraging news for the industry.

So, if this pilot project succeeds - and if concerns of the environmental groups are met - farmed cod could become an everyday choice on our supermarket shelves.