The tuna resources of the eastern central Atlantic have been the object of an intensive fishery for over thirty years, and have been the object of numerous studies conducted under the coordination of the International Commission for the Conservation of Atlantic Tunas. This document presents a summary of current knowledge of the biology of the principal species of tuna in the eastern tropical Atlantic, the oceanographic environment of tunas and the influence of environmental conditions on product ion. A detailed description of the principal fisheries of the region and the history of their development is presented as well as the methods of population dynamics used to assess the abundance of the stocks and to estimate changes in the level of their exploitation.