Frisian Islands at water depths of 2–10 m the common scoter appears in internationally meaningful stocks. Fishes, mussels and shellfish The typical mussels of the Wadden Sea are the common cockle (Cerastoderma edule) and the blue mussel (Mytilus edulis). While the common cockle is omnipresent, wild growing blue mussels are less common than in the southern Wadden Sea. They suffer from the expansion of the Pacific oyster which benefit from the warmer winters. The sand gaper was probably introduced by the Vikings from America; the American piddock arrived at the end of the 19th century, while the appearance of the Atlantic jackknife clam in the Wadden Sea is known since 1976. Of the shellfish, the common shore crab (Carcinus maenas) is of huge importance, because it devours 10% of the whole Wadden Sea´s biomass. Also, numerous brown shrimp and barnacles can be found. Besides the seal the lugworm is probably the most famous animal in the Wadden Sea. Only some small fishes are completely domestic in the mudflat, e.g. eelpout (Zoarces viviparus), sand goby (Pomatoschistus minutus) and sea scorpion (Myoxocephalus scorpius). Many other species use the area rich in food and oxygen and protected from predatory fish as spawning grounds. Flatfish like plaice are important to name, but also the garfish (Belone belone) is active in the eastern part of the Atlantic. The National Park History The protection of the Wadden Sea of Schleswig-Holstein is a target on nature conservation since the 20th century. In the 1920s, the first concerns were the protection of areas in the Wadden Sea e.g. "Sylt-Nord" and the Morsum cliff (Sylt). Since 1940, 11 conservation areas were established in North Frisia targeting mainly the protection of animal species, especially birds. During the development of the conservation areas, protecting biotopes became more and more important. In the 1960s, plans were first made for conserving the entire area of the Wadden Sea. In 1963 the Wadden Sea Conservation Station demanded a "Großschutzgebiet Halligmeer" (protection of the area around the small undyked islands off the coast of Schleswig-Holstein). The local hunting association firstly proposed the term national park in relation to the Wadden Sea in 1972, two years after the establishment of the Bavarian Forest National Park. In 1973 the ministry of agriculture proposed a bill which was withdrawn the following year because of strong resistance by locals. In 1975, a first scientific conference about the conservation of