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
Mediterranean mussel edulis" and "Mytilus trossulus", when they are found in the same locality. "M. galloprovincialis" is considered the most warm-water-tolerant species of the three, and has the most southerly distribution in Europe and North America. In Europe, "Mytilus galloprovincialis" is found in the Mediterranean Sea and the Black Sea, and on the Atlantic coasts, in Portugal, north to France and the British Isles and Norway. Recently this species has also been found in the European Arctic including northern Norway and Svalbard In the northern Pacific the species is found along the coast of California, where it was introduced from Europe by