The study area for this work includes all the southern edge of the Bay of Biscay, from the north-west Iberian Peninsula to the southern half of the French shelf. The principal aim of this article is to provide a complete overview of the physical oceanography of the area, mainly in its mesoscale aspects, of which there are few published studies, and the implications for early fish life history stages. The results showed the existence of two space and temporal scales for most of the physical processes that occur in the Bay of Biscay, a macroscale for seasonal time periods and a meso and submesoscale for the periods between seasons. The importance of local phenomena, such as upwelling or the variability of the Poleward Current, was observed. The interaction of both scales on these physical processes is discussed and the need for sampling at the submesoscale level to determine the distribution of ichthyoplankton is considered. Moreover, the mesoscale physical oceanography study is essential to improve the knowledge of interactions between strategies and environmental conditions that result in a significant mortality reduction in fish early stages.