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 years of existence connected to the White Sea through Karelia due to the isostatic depression caused by the ice sheet of the earlier Saalian ice age. Little is known about the Baltic Sea during the oscillations of the Weichselian ice age, the last glaciation. The first Weichselian glaciations, corresponding to MIS 5b and 5d, penetrated parts of the Baltic Sea depression from north to south but did not got south beyond the Åland Islands. The Weichsel ice sheet reached northern Denmark about 65–60 thousand years ago. When the last ice sheet began to retreat north from the Baltic Sea depression