The little-known records of a Rochelais notary, Jacques Cousseau, active from 1602 to 1653, shed new light on the salt cod trade linking Basque ports, La Rochelle, and fishing grounds in present-day Canada. Each point in this triangular trade contributed specific resources: the Basque ports brought ships and crews, La Rochelle provided salt and capital, while Canada had seemingly limitless fish stocks. Cousseau’s minutes reveal distinctions among the Basque ports, different modes of participation adopted by Rochelais merchants and sailors, as well as the regional evolution of transatlantic fishing grounds. Against the backdrop of their complementarity in the fishery, Basque and Rochelais actors competed in a sector that sprouted as a secondary source of income for fishing outfits, and burgeoned as the century advanced—the transatlantic fur trade.