Richesses et productions marines de la baie du Mont Saint-Michel : La mytiliculture

The Mont-Saint-Michel is at the end of the Norman-Breton gulf, in the angle formed by Cotentin to the east and Brittany to the south. The pointe du Grouin, to the NW, and the pointe de Champeaux, to the NE, circumscribe it to the north, whereas to the south, its flat coast melts into the Dol Marsh and the polders which border the Couesnon (fig. 1). The bay currently has a marine surface of 37,000 ha, about 3/5 of which is emerged during spring tide. The tidal amplitude is the strongest in Europe with over 14 m. Considering the extreme flatness of the tidal zone, the flow covers very long distances (about 20 km in the axis of the Sélune). This results in some very strong currents which create an important mixing of the water. These currents renew the water mass from the NW (pointe du Grouin) and, at the ebb, flow back to the N-NE.