Postglacial recolonisation route of Coregonus sp. Map showing the most likely recolonisation routes of Coregonus sp. via the postglacial Elbe River system and further into the Limfjord. Immediately after the last glaciation the Gudenaa River flowed into the Limfjord, but later it changed outlet towards the Kattegat Sea . Arrows indicate the direction of immigration.