Morphobiological Characteristic of the Arctic Lamprey Lethenteron camtchaticum (Petromyzontidae) in the Basins of Large Rivers of the Arkhangelsk Region, Russia

Data have been presented on the morphobiological parameters of the anadromous Arctic lamprey Lethenteron camtschaticum (Tilesius, 1811) in spawning stocks of large river basins of the Arkhangelsk region - Onega, Severodvinsk and Mezen. The clinal variability of linear-weight parameters, absolute fecundity, and a number of plastic characters was revealed, according to which the lamprey population from the Northern Dvina River occupies an intermediate position between the lampreys of the Onega and Mezen rivers. Higher average values of biological indicators (length, body weight, fecundity) were noted in European lamprey populations compared to those in individuals from the Far Eastern part of the range.