European River Lamprey Lampetra Fluviatilis in the Upper Volga: Distribution and Biology

Abstract

After the construction of the Volga Hydroelectric Station and other dams, migration routes of the Caspian lamprey were obstructed. The ecological niches vacated by this species attracted another lamprey of the genus Lampetra to the Upper Volga, which probably came from the Baltic Sea via the system of shipways developed in the 18 th and 19 th centuries. Based on collected samples and observations from sites in the Upper Volga basin, we provide diagnostic characters of adults, and information on spawning behavior. Silver coloration of Lampetra fluviatilis was noted for the first time and a new size-related subsample of “large” specimens was delimited, in addition to the previously described “dwarf”, “small” and “common” adult resident sizes categories. The three water systems: the Vyshnii Volochek, the Tikhvin and the Mariinskaya, are possible invasion pathways, based on the migration capabilities of the lampreys. Dispersal and colonization of the Caspian basin was likely a combination of upstream and downstreams migrations. First, the lampreys migrated upstream along the rivers of the Baltic basin until they reached the water-parting line, followed by mostly downstream dispersal into rivers of the Caspian basin. Dispersal in the Volga River was similar, in accordance with the migration cycle of this opportunistic lamprey species.