History of the North Sea great herring fishing industry resulting in Scotland becoming a European leader in that industry. During the First Schleswig War (1848–51), the Crimean War (1854–56) and the Second Schleswig War (1864), belligerents took steps to reduce or eliminate commerce in the North Sea by their enemies. In the first Schleswig War, Denmark was able to halt maritime commerce by Germany in the North Sea and in the second, imposed tolls on ships crossing through the Danish straits between the Baltic and North Seas. The Crimean War saw British and French expeditions sent into the Baltic to prevent Russian ships' egress into
Migration of marine species in the Northern Atlantic Ocean outside their normal range and into more northern waters causing an array of ecological, economic, and fishery management problems. William Cheung, a professor at the University of East Anglia, in the Sea Around Us Project at the University of British Columbia concluded that the oceans were warming at an average of per decade and at per decade in tropical waters. However, the north-east Atlantic has been warming at a rate of per decade. Cheung and his colleagues were able to get these estimates by using the mean temperature of catch. They used data from 990 species within 52 marine ecosystems