Finding of the American Signal Crayfish <i>Pacifastacus leniusculus</i> (Decapoda: Astacidae) in the Leningrad Region (Russia)

Abstract

The American signal crayfish Pacifastacus leniusculus (Dana, 1852) was first found in the lake Zaprudnoye of the Saimaa Canal system between lake Saimaa (Finland) and Vyborgsky Bay (Russia). The Saimaa Canal belongs to a large lake-river network connecting the waters of the Gulf of Finland and Lake Ladoga. On this basis, a wide distribution of P. leniusculus is predicted in the water bodies of the Leningrad Region and the North-West of Russia as a whole. The captured part of the population was 9 individuals. The sex ratio in the population was significantly biased toward males: 8 ♂ и 1 ♀.