Fos-sur-Mer is a commune of 15,700 people ( 2005 ) . It is found in the region Provence-Alpes-C Ã te d'Azur in the Bouches-du-Rh Ã ne department in the south of France .
Fos-sur-Mer is a commune in the Bouches-du-Rh Ã ne department in southern France .