Coregonus widegreni, also called the Valaam whitefish, is a putative species of freshwater whitefish, a part of the common whitefish complex (Coregonus lavaretus sensu lato) from Northern Europe. It is a demersal form of freshwater whitefish that feeds on benthic invertebrates. It spawns in late autumn, and can reach a length of 55 cm maximum. It is characterized by a low gill raker density.
In the strict sense the name C. widegreni refers to a population of whitefish that inhabits relatively deep waters (50–150 m) of Lake Ladoga in Northwest Russia.Freyhof J, Kottelat M (2008) Coregonus widegreni The IUCN Red List of Threatened Species, 2016 version. More often the range is thought to comprise coastal areas of the Baltic Sea (except southern section of the Swedish coast) and several larger lakes in Sweden (e.g. Vänern, Vättern) and Northwest Russia (Onega).Kottelat, M. and J. Freyhof, 2007. Handbook of European freshwater fishes. Publications Kottelat, Cornol, Switzerland. 646 p. It is one of several types of whitefish co-distributed in Northern Europe and exhibiting different breeding and feeding habits. In the Northern Baltic, C. [lavaretus] widegreni has referred to bottom-feeding whitefish that spawn in the sea ("lesser sparsely-rakered whitefish", in contrast to migratory anadromous whitefish referred to as C. lavaretus lavaretus.Säisä, M., Rönn, J., Aho, T., Björklund, M., Pasanen, P. and Koljonen, M.-L. (2008) Genetic differentiation among European whitefish ecotypes based on microsatellite data. Hereditas 145, 68–83. doi:10.1111/j.0018-0661.2008.02050.x
In contemporary Nordic usage, C. widegreni is not recognised as a distinct species, but at most as an ecotype or morphotype of Coregonus lavaretusSiika (Coregonus lavaretus) Luke Natural Resources Institute Finland or of Coregonus maraena.Morfotyp: Coregonus maraena morphotype widegreni - sandsik Dyntaxa Svensk taxonomisk databas (Sweden)
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