The bay of Mont-Saint-Michel is a unique and remarkable natural site. Around a hundred species of fish frequent the area: migratory fish – Atlantic salmon (Salmo salar) or eels (Anguilla anguilla) – and sedentary fish such as the numerous hogfish (Liza ramada) which feed on diatoms, ochre-coloured micro-algae deposited on the sand. This abundance of fish benefits the colony of more than 85 calf seals (Phoca vitulina) that call these waters home. In summer, they are joined by a dozen grey seals (Halichoerus grypus).