Non-native freshwater fish species in the Lena River basin

Abstract

The article provides the data on composition of the non-native fresh water species in the basin of the Lena River. We indicate the years they have been discovered and describe the vectors of their invasion into the water reservoir. In different years, 9 non-native freshwater species have been introduced into the Lena River ecosystem: sterlet, European cisco, Arctic cisco, bream, Chinese carp, Amur carp, silver carp, European pike-perch and Amur sleeper. In general, the invasion of fish species in the Lena River basin is characterized by the following vectors: 1 – deliberately introduced (sterlet, European cisco, Arctic cisco, bream, Chinese carp, Amur carp, silver carp, European pike-perch); 2 – selfdispersing (bream, Amur carp). In recent years, Amur carp and bream have been encountered in the river’s middle and lower reaches; 3 – accidentally introduced (Amur sleeper). We identify deliberate introduction as the key invasion vector in the basin of the Lena River. Bream and carp have acclimatized successfully. Moreover, Amur sleeper has spread to the estuary of the Olyokma River (November 2021), having passed 1350 km in 10 years. Its migrant capacity made 135 km/year. Thus, being a highly invasive species, Amur sleeper can naturalize successfully. Current downstream dispersal of bream, Amur carp, Amur sleeper, as well as pike, ide, roach and perch is associated with general 

climate warming in the Arctic area, which creates favorable conditions for the fish dispersal. Self-dispersal of nonnative species in the Lena River basin meets the definition of biological invasion and may create complications in interspecies competitive food relationships, bring new pathogenic organisms and rearrange parasitic communities. We conclude that the formation of the Lena River basin ichthyofauna is in progress.