Shellfish farming is a common industry along European coasts. According to the 2005–2006 data from the French National Shellfish Farming Committee (CNC – Comité National de la Conchyliculture 2010; see Table 1 for a list of acronyms and abbreviations used in this chapter), Spain is the largest shellfish producer in Europe (∼270,000 t) and France ranks second, producing 200,000 t of shellfish annually. France is the leading European oyster producer, with an annual output of 130,000 t of Crassostrea gigas, and ranks fourth in the world after China, Japan, and Korea. The top three European mussel (Mytilus edulis and Mytilus galloprovincialis) producers are Spain (260,000 t), Denmark (80,000 t), and France (65,000 t). For other shellfish, the French annual output level is 15,000 t for king scallops (Pecten maximus) and a few thousand tons for Ruditapes clams (Ruditapes decussatus and Ruditapes philippinarum) and cockles (Cerastoderma edule). The economic impact of shellfish farming is considerable; despite fairly long production lead times and difficult operating conditions, shellfish farming generates annual sales of more than 650 million Euros in France, owing to its high added value.