History of the North Sea United Kingdom and Germany signed the Treaty of Heligoland. The Cod War of 1893 erupted between Denmark and Britain over fishing territories. Denmark declared a fishing territory of 13 nautical miles (24 km) around their shores which included Iceland and the Faroe Islands. Britain did not acknowledge this claim. Tensions in the North Sea were again heightened in 1904 by the Dogger Bank incident, in which Russian naval vessels mistook British fishing boats for Japanese ships and fired on them, and then upon each other. The incident, combined with Britain's alliance with Japan and the Russo-Japanese War led to an
Fishing in the North Sea the 19th century large quantities of herring were produced in Scotland. Today mainly mackerel, Atlantic cod, whiting, coalfish, European plaice, and sole are caught. In addition, common shrimp, lobster, and crab, along with a variety of shellfish are harvested. In recent decades, overfishing has left many fisheries unproductive, disturbing the marine food chain dynamics and costing jobs in the fishing industry. Herring, cod and plaice fisheries may soon face the same plight as mackerel fishing which ceased in the 1970s due to overfishing. Since the 1960s, various regulations have attempted to protect the stocks of fish such as limited fishing