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
Fish species of the Neretva basin its many tributaries, lakes and marshes provides rich freshwater habitat for its native, as well as for introduced non-native fish species. There are deep canyon as well as wide valley sections with both fast flowing rapids with side-pools, and narrow sections with deep, still waters running slowly. The flowing water can be any combination of fast or slow, deep or shallow, open or protected by canyons, rocks, tree roots and undercut banks, and shaded by vegetation on the bank or exposed to full sunlight. This variation ensures that a relatively large number of fish species are able to find suitable