The Baltic herring (Clupea harengus membras) is a sub-species of the Atlantic herring that lives in the Baltic Sea. It is mostly about 20 cm long with a silvery lustre and dark bluish green back that has adapted to the changeable salinity water and therefore it is possible to find it almost everywhere in the Baltic Sea. The Baltic herrings form shoals whereas the shoals of younger fish concentrate into higher water layers and older ones into deeper layers. In the winter the Baltic herrings do not eat at all and but remain in slowly moving shoals close to the bottom in the depth of several tens of meters. From early spring to late autumn there are trips to upper water layers and back in the morning, because the Baltic herring do not tolerate bright sunshine but the upper layer is warmer and more oxygen rich and there is more food. The Baltic herring is one of the most important fish in the whole of the Baltic Sea and the Estonians’ feeder for centuries. In 2007 the Baltic herring was announced the national Estonian Fish.
About this stamp in philately foorum.