Once it was said, cod was so abundant that fishermen in some parts of the world boasted they could walk on the backs of the fish to find their catch. Today we see astonishing changes. The existence of commercially exploitable wild fish stocks in general and cod in particular is threatened in traditional fishing areas the world over. European seas are especially hard-pressed at the moment and nowhere has the decline been more savage than in the North Sea where stocks of cod, by far the most important of all fish where human consumption is concerned, have fallen by 60 per cent in 20 years. Marine scientists say a total moratorium on cod fishing is now necessary.