North Sea autumn spawning herring is considered and assessed as a single stock, consisting of four spawning components, which are genetically homogeneous. Some mixing with other neighboring stocks occurs, particularly in Division IIIa (with Western Baltic Spring Spawning herring) (ICES, 2015b).
Image: "Whitehead, 1985 FAO Species Catalogue. Vol. 7. Clupeoid fishes of the world (suborder Clupeoidei). An annotated and illustrated catalogue of the herrings, sardines, pilchards, sprats, shads, anchovies and wolf-herrings" via FishBase