Baltic Sea as species in 2005 and 2018 respectively, having formerly been confused with more widespread relatives. The tiny Copenhagen cockle ("Parvicardium hauniense"), a rare mussel, is sometimes considered endemic, but has now been recorded in the Mediterranean. However, some consider non-Baltic records to be misidentifications of juvenile lagoon cockles ("Cerastoderma glaucum"). Several widespread marine species have distinctive subpopulations in the Baltic Sea adapted to the low salinity, such as the Baltic Sea forms of the Atlantic herring and lumpsucker, which are smaller than the widespread forms in the North Atlantic. A peculiar feature of the fauna is that it contains a
History of the North Sea it gained significant economic importance in the 1960s as the states on the North Sea coasts began full-scale exploitation of its oil and gas resources. The North Sea continues to be an active trade route. The countries bordering the North Sea all claim the of territorial waters within which they have exclusive fishing rights. Today, the North Sea is more important as a fishery and source of fossil fuel and renewable energy, since territorial expansion of the adjoining countries has ceased. One of the earliest recorded names was "Septentrionalis Oceanus", or "Northern Ocean" which was cited by Pliny. However, the