An industrial fishery is a geographical area of operation of a complex of capitals whose form of organization is the firm and whose medium of operation is fishing vessels. Tuna fisheries are among the most highly capitalized and valuable fisheries in the world. This paper distinguishes between two relations that function simultaneously at the point of production in capture fisheries to investigate an empirical account of a ‘commodity frontier’ in tuna (Moore 2010a,b). The first is the vertical relationship between capital and the environmental conditions of production. The second is the horizontal relations between competing fishing firms as they transform nature to produce commodities for the world market. The paper traces the emergence of the European tuna fleet in its search for new commodity frontiers, from the Bay of Biscay (1860s) to the Eastern Tropical Atlantic (1950s) and the Western Indian Ocean (1980s). The primary empirical focus is the Indian Ocean, where, after appropriating an initial, highly productive surplus, the European fleet intensified fishing activities and has partially undermined the natural conditions for the reproduction of its industrial-scale operations. I argue that the complex dynamics of capture fisheries can be better understood through the prism of a commodity frontier.