metal pollution from salmon farms has caused serious threats to wildlife in some of Scotland's sea lochs. According to a study of the Scottish Environment Protection Agency ( sepa ), levels of copper and zinc in sediments beneath fish farms is 24 times as high as the safety limits proposed by the Agency.

Nearly 350 fish farmers in Scotland use copper-based paints as antifouling agents to prevent the fish cages from becoming clogged by mussels, algae and seaweed. They use zinc to galvanise the cages and to feed salmon.

sepa says that sediments within 30 metres of seven of the farms were "severely contaminated'. It has resulted in "probable' harm to seabed invertebrates like lugworms and crustaceans by damaging their reproductive abilities or even killing them.