Salt marshes are grassy meadows covered by the sea during high tidal coefficients. In the Middle Ages, the lords wanted to take advantage of all land suitable for sheep farming. Dykes were created from the 10th century, and a brebiage right allowed the monks of Mont-Saint-Michel to take one ewe from each herd in the 11th century. Pilgrims completed the renown of salt marshes sheeps. The Prés-Salés du Mont-Saint-Michel AOC (Controlled Designation of Origin) was granted in 2009 and marketed a year later.