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
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