Diversity and distribution of European whitefish (Coregonus lavaretus) in the watercourses of Murmansk region

European whitefish (Coregonus lavaretus) is a highly polymorphic species, but the wider scale diversity and distribution of sympatric morphs in subarctic lakes of northwestern Russia has not been recently studied and analyzed. The aim of the present study was to investigate diversity and distribution of whitefish morphs in different sized lakes and watercourses of Murmansk region. Our study of the water bodies in four major river basins of Murmansk region revealed the presence of two whitefish morphs: sparsely rakered (sr) and medium rakered (mr). The mr morph is less common and observed only alongside the sr whitefish. In general, in sr whitefish the number of gill rakers ranges between 15 and 31, and in mr whitefish between 27 and 44. Among whitefishes with 27 to 31 gill rakers, both sr and mr morphs were observed and distinguishable by the shape of the rakers. In the studied sr whitefish populations, relatively long and short rakered whitefish morphs were found. In Lake Kuetsyarvi (Pasvik River basin), the sr and mr whitefish formed additional slow- and fast-growing ecological morphs. The four whitefish morphs in Lake Kuetsyarvi specialize to different ecological niches correlating with morphological and behavioral differences. The observed diversity and distribution of whitefish in the Murmansk region requires genetic studies of the population to assess the origins of divergence.