Coastal habitat is suitable over large portions of the European continent, including perimeters of the Celtic Sea, English Channel, Bay of Biscay, Irish Sea, Sea of the Hebrides, North Sea, Norwegian Sea, Baltic Sea, Gulf of Riga and Mediterranean Sea. Furthermore, some European countries offer suitable otter habitat hundreds of kilometres inland from the nearest sea. For example, in Romania, not only are European otter found within the Danube Delta, but far inland within the Carpathian Mountains. In Poland and Bulgaria, otters are found far inland in the rivers that have sufficiently high water quality and have a minimum of hydroelectric installations. The European otter, in fact, can be found in mountain valleys as high as 1400 metres in places such as Bulgaria, including numerous small watersheds in West Rhodopy Mountain, Bulgaria. In Turkey, however, overgrazing of riparian terrestrial cover, human hunting and water pollution have almost extirpated L. lutra from inland areas, except for parts of the Coruh River. In Soain L .lutra is found along parts of the coastline but also in interior riparian zones in such ecosystems as the Iberian sclerophyllus forests, where populations may be considered relicts of broader prehistoric distributions.
- C.Michael Hogan. 2011. ''European otter". Encyclopedia of Earth. Topic ed. P.Saundry. Encyclopedia of Earth http://www.eoearth.org/article/European_otter?topic=49540