Ichthyofauna of the Iskar River Section Affected by the Hydropower Cascade „Middle Iskar"

Luchezar Z. Pehlivanov*, Stefan A. Kazakov
Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 2 Major Yurii Gagarin Str., Sofia, BULGARIA
*Corresponding author: luchezarpehlivanov@gmail.com
Abstract. The study aimed to assess the impact of a cascade of 5 small hydropower plants on the composition and structure of the recent fish communities in the affected area of Iskar River. The field surveys cover the river sections up- and downstream the 5 dams, the dam lakes and the fish passes of the dams. Fifteen fish species were recorded in the dam lakes. Limnophylous and eurytopic species predominate the communities. The high species richness and the presence of large-size fishes can be considered as an indirect indication of relatively stable conditions in the dam lakes. Eleven fish species were found in the studied river stretches. The ecological status of these river sections assessed by standardized fish indices were determined as Good and High. Both the abundance and size-age compostion of some type-specific species correspond to "Favorable" conservation status. Totally 8 fish species were recorded to migrate up- and downstream through the fish passess. The most intensive upstream migration was found at the end of May when 2 to 5 species migrated through different dams.
Key words: HPPs, Fish communities, Iskar River, Dams, Fish passes, Ecological state.

Ecologia Balkanica, 2019, Special Edition 2, pp. 107-115
Article № eb.19SE217 [Full text - PDF]pdf

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