park region are allowed by law. On average approximately 10.000 tons of common mussels are harvested. From the beginning of April until mid of June harvesting is generally prohibited. Catching common cockle and common razor shells is prohibited since 1990. Even before the prohibition, it was economically unimportant due to natural stock decreases in Schleswig-Holstein during hard winter seasons. Pacific oyster (Magallan gigas) cultivations are limited to a 30 ha big area near Sylt. These oysters are kept in heated ponds during winter. About 1 million oysters are harvested and sold on Sylt annually; approximately one third is eaten local. The Pacific oyster has widely spread in the Wadden Sea during the last years. The former blue mussel beds evolved into oyssel reefs. Attempts to catch the thick trough shell (Spisula solida) were successful in the beginning of the 1990s. During the hard winter in 1995/96 all the shells fell victim to the unusual cold weather. Since the end of 2016 thick trough shell fishery is prohibited in the national park. Aquaculture and hunting An experimental station for marine aquaculture is located in Büsum. The plants water supply with North Sea water comes through a pipeline which begins in the national park. While hunting in the national park area is prohibited since 1999, some hunters are still active on the Hallig Islands which are surrounded by national park conservation zones. Agriculture Besides tourism agriculture is the most important source of income for the west coast of Schleswig-Holstein. Especially southern Dithmarschen has been and still is an important agricultural export area. While most of the agriculture happens outside of the national park area (except for sheep farming), it still has some influence on the national park, for example water travels through Grüppen (drainage channels) from the fields into the North Sea. Only sheep grazing on salt marshes happens to be a problem with agriculture and the national park. Since the first settlements salt marshes were used for grazing and sheep farming. Since the 1980s intensive grazing got subsidised by the government of Schleswig-Holstein. Nowadays only dikes itself and the dike foreshore areas shall be intensively grazed because of coastal defence manners. Salt marshes which are located more seawards shall be spared out. From 1991 to 1996, shepherds received compensation for relinquishing the intensive grazing of seaward salt marshes as a part of the "Küstenstreifen-Programm". In the disused salt marshes water drainage