Mackerel is a pelagic fish that can swim at greatspeeds, and in summer and autumn it moves in huge shoals along the coast of Norway and into Skagerrak, the North Sea and the southern reaches of the Norwegian Sea. In Europe, the mackerel family is divided into three main stocks: one to the west of the British Isles, one in the North Sea and Skagerrak and a third in the Gulf of Biscay. The mackerel fished in the North Sea, Skagerrak and the Norwegian Sea are generally managed together with the western stock of mackerel.