Preliminary results of the study of populations of the freshwater pearl mussel from streams of the Lopshenga River basin on Onega Peninsula in Arkhangelsk oblast

Streams of the Lopshenga River basin (Summer Coast of the White Sea) are studied. Sections of the Kamennyi and Zhemchuzhnyi streams with relatively high population densities of the freshwater pearl mussel, the populations of which can be attributed to those that are aging, but with a high abundance, are detected. It is noted that the ratio of morphological forms of the freshwater pearl mussel in the streams of the Lopshenga River basin is characteristic of more southern populations of this species.