nchovy Engraulis encrasicolus concentrates in the SE corner of the Bay of Biscay during the spawning season from May to July, especially in the plumes of the French rivers Gironde and Adour. In autumn, juveniles are found dispersed in many different habitats, off the French and Spanish coasts, outside the shelf break and in a larger box than the SE corner of the Bay. A 3D hydrodynamic model capable of reliably simulating the flow field in the surface layers was developed by IFREMER. It was used as a first fisheries application to simulate the transport processes affecting Biscay anchovy from the egg to the juvenile stages in 1999. Juveniles were collected in different sites during a survey in September 1999. Their birth-dates were estimated by interpreting the otolith increments. Virtual buoys were released on the grid of the hydrodynamic model at the birth-dates and their trajectories were tracked. The buoys that were found close to the juvenile sampling sites at the appropriate dates were selected as potential transport trajectories experienced by the larvae and juveniles during their development. The probabilities of transport from the spawning to the potential nursery grounds were estimated. A simplified spawning model was used to simulate the transport pattern and the probable distribution of juveniles at the population scale. The simulation shows a general transport to the south-west across the Bay of Biscay. SE Biscay appears as a retention area mainly seeded by the spawning grounds located over the French shelf. An advective system to the west would spread along the Spanish shelf. The distribution of anchovy juveniles predicted by the model is coherent with the September 1999 survey. The transport model was forced by the climatic conditions in 1999. The wind regime in 1999 was close to the average regime from 1986 to 2000. Therefore this transport model would be representative of the general transport scheme of anchovy larvae and juveniles in the Bay of Biscay.