Clupea Clupea Clupea is genus of planktivorous bony fish belonging to the family Clupeidae, commonly known as herrings. They are found in the shallow, temperate waters of the North Pacific and the North Atlantic oceans, including the Baltic Sea. Three species of "Clupea" are recognized. The main taxa, the Atlantic herring ("Clupea harengus") and the Pacific herring ("Clupea pallasii") may each be divided into subspecies. Herrings are forage fish moving in vast schools, coming in spring to the shores of Europe and America, where they form important commercial fisheries. The species of "Clupea" belong to the larger family Clupeidae (herrings, shads,
Geology of the Baltic Sea are however absent in the whole Baltic area except for the southern fringes. Scientists do not agree on how the present depression the Baltic Sea occupies formed. Scholars like Voipio (1981) and Šlaiupa (1995) consider the depression to have been formed in the Cenozoic, before the Quaternary, by tectonic processes. Some others like Marks (2004) stress erosion was key to the formation of the depression. In the Cenozoic, long before the Quaternary glaciations the Baltic was the site of a large river called Eridanos. This river drained west in direction towards the North Sea. The Neogene uplift of the South