The mackerel is a pelagic, fast-swimming fish that in summer and beyond autumn appears in large shoals along the coast and out in the Skagerrak, the North Sea and in the southern Norwegian Sea. In Europe, the mackerel is divided into three main stocks; one west of the British Isles, one in the North Sea and Skagerrak and a third in Biscay. The mackerel fished in the North Sea, Skagerrak and the Norwegian Sea are managed together with the western stock.