''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 The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of ...

form of freshwater whitefish that feeds on

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

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 Lake Ladoga (; rus, Ла́дожское о́зеро, r=Ladozhskoye ozero, p=ˈladəʂskəjə ˈozʲɪrə or rus, Ла́дога, r=Ladoga, p=ˈladəɡə, fi, Laatokka arlier in Finnish ''Nevajärvi'' ; vep, Ladog, Ladoganjärv) is a fresh ...

in Northwest Russia.Freyhof J, Kottelat M (2008
''Coregonus widegreni''
The

IUCN Red List of Threatened Species The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biologi ...

, 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). 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. avaretuswidegreni'' has referred to bottom-feeding whitefish that spawn in the sea ("lesser sparsely-rakered whitefish", in contrast to migratory

anadromous Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousan ...

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 lavaretus ''Coregonus lavaretus'' is a species of freshwater whitefish, in the family Salmonidae. It is the type species of its genus ''Coregonus''. There are widely different concepts about the delimitation of the species ''Coregonus lavaretus'' and abou ...

''Siika (''Coregonus lavaretus'')
Luke Natural Resources Institute Finland or of '' Coregonus maraena''.Morfotyp: ''Coregonus maraena'' morphotype ''widegreni'' - sandsik
Dyntaxa Svensk taxonomisk databas (Sweden)

References

widegreni Fish described in 1863 Freshwater fish of Europe {{Salmoniformes-stub