Hydrographic and climatic conditions have been found to be one of the most important factors that can influence the distnbution and behaviour of adults, juveniles and early stages of fish. This relationship, which has been pointed out by several authors, is also the main objective ofthe SEFOS project, which studies the relationship between the distnbutions and migrations of commercially important fish species and the oceanography of the European shelf edge. Within this framework, the Bay of Biscay presents special oceanographic and climatic conditions that could intluence the aggregations of food and larvae in retention areas throughout this zone, which is one of the most important nursery areas for several fish species and seasonal migrations of blue whiting, horse mackerel and mackerel This paper presents the results of a multidisciplinary study of the relationship between the oceanographic conditions ofthe Bay ofBiscay and the distribution ofboth early stages - eggs and larvae - and adult fish ofhorse mackerel, mackerel and blue whiting for the period 1994-1996.