Environmentalists argue sea cage fish farming will not compensate for the decline in wild fisheries because it takes, according to a paper in Nature, three tonnes of wild fish to produce one tonne of farmed salmon. So aquaculture is hardly helping wild stocks if it takes feed for farmed fish from the seas. The Research Council of Norway has predicted that "within three to eight years the lack of marine oil raw materials could hinder the growth of Norway's major salmon farming operations" ­ 80% of all fish caught by Norwegian trawlers is already used to provide feed for the fish farming industry. The International Fish and Fish Oil Manufacturers' Association predicts that aquaculture may consume 90% of the world's fish oil by 2010. It currently uses up to 75% of the world's fish oil. WWF wants annual quota system limiting maximum amount of feed at farms.It claims it has been calculated that to keep up with demand for fish meal and oil from European salmon farming, the industry will need a marine support area' of between 40-50,000 times the surface area of cultivation ­ equivalent to 90% of the primary production area of the North Sea. The stocking density of cages is another sore point. Salmon cages seem densely stocked to a layman's eye ­ and this could yet develop as contentious in the way confinement has proved a sore point in European pigmeat. The Scottish Executive and Parliament are in the process of developing a strategy for aquaculture but constraint on Scotland will be in the context of global aquaculture developing exponentially. {{FEATURES }}