The Resident European River Lamprey Lampetra fluviatilis (Petromyzontidae) and its Habitat Conditions in the Upper Reaches of Tributaries of the Pola and Msta Rivers

Abstract— The results of the study of local populations of the resident form of the European river lamprey Lampetra fluviatilis in medium and small watercourses (tributaries of the Pola and Msta rivers), located at a distance of ~700 km from the sea, in the native part of the species range, are presented. Such populations are still poorly studied, despite the fact that they ensure the preservation of the range under conditions of fragmentation of river system. The captured adults are typical representatives of the resident form, with a slight variation in the dentition. The population density of lamprey larvae in most of the studied habitats is low and average in a small part of them. The habitat conditions of ammocoetes are determined to be optimal, however, due to the peculiarities of small watercourses, their habitats are vulnerable to the negative effects of environmental factors.