Assessment of the impact of construction of multiple hydropower plants in Mongolia on fish fauna of Selenga River downstream and Lake Baikal
This paper deals with the species composition and the ecological characteristics of fish fauna of the Selenga River basin. The possible risks and their impact on the ichthyofauna of the downstream channel of the river and Lake Baikal are assessed with regard to the expected changes in natural flow and other factors resulting from the construction of hydropower plants and reservoirs in Mongolia. The artificial regulation of flow regime would result in reduction of the migratory routes of migratory fishes (the endangered Baikalian sturgeon, the valuable commercial Baikalian omul and grayling), partial loss of their spawning grounds, disruption of the spawning area of non-migratory fishes (including the endangered lenok and the taimen). This would also disturb the conditions of spawning migrations of all fish species and eggs incubation and reduce spawning and feeding areas. The conditions of fish reproduction in coastal systems in Lake Baikal tributar- ies will be changed. A significant decrease of reproduction efficiency of migratory and non-migratory fishes in Selenga River, its Delta and coastal systems of other rivers, degradation of the gene pool of valuable fish species, increase of the number of endangered species, replacement of commercial fish species with noncommercial ones are expected as a result of flow regulation. The loss of unique renewable bio-resources of Lake Baikal and the damage to the fishery could be assessed as an ecological catastrophe.