The position of fishing in the European economy changed substantially during the early modern period. This chapter focuses on elucidating the general relationships and constraints which moulded the fishing industry and the fish trade, and the general fortunes of the cod and herring industries, rather than technical considerations. Every type of fishery is subject to enormous fluctuations in the catch. Winds and fluctuating temperatures add to the natural hazards, not just during the fishing period itself, but during the whole life cycle of the fish. In most ranges of economic activity in Europe there is evidence of a dual economy. Donald Coleman has pointed this out in relation to the cloth industry, and further investigation would shed light on its action in many other spheres. The chapter discusses Scottish herring fishery, English herring industry, Dutch herring fishery, French herring fishery, cod fishery, whale fishery, pilchard fishery and mackerel fishery.