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
Blue cod change. Since a number of evidence indicated that blue cod are relatively sedentary, the fishing pressure may lead to potential local depletion. Recent studies showed that the genetic differences were significant between mainland List of islands of New Zealand population and Chatham Island population. On the other hand, the differences within mainlandList of islands of New Zealand populations were limited while the pattern of the isolation by distance was detected. Further research using microsatellite DNA markers suggested that some significant genetic differences between mainland population exist which indicate the potential long-distance dispersal, but the dispersal rate is too low to