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
Wadden Sea Agreement Wadden Sea Agreement The Agreement on the Conservation of Seals in the Wadden Sea is an agreement between Wadden Sea countries, aimed at protection of seals and concluded in the aegis of Convention on Migratory Species (CMS) in 1990. Common seals, or harbor seals, are nearly threatened true seal species, inhabiting temperate and Arctic marine coastlines of the Northern hemisphere. They are found in coastal waters of the northern Atlantic and Pacific Oceans as well as those of the Baltic and North Seas. Harbor seals are brown, tan, or gray, with distinctive V-shaped nostrils. An adult can attain a length