Investigation of fish behavior at Iron Gate II Hydropower plant by acoustic telemetry

Abstract

The Iron Gate II HPP represents the first barrier for long migratory fish species (sturgeons, shads, eels) on their spawning migration from the Black Sea to the upstream parts of the Danube River. It was built in 1984 on rkm 864 while Iron Gate I HPP was built on rkm 943 in 1970, both without fish passages. The establishment of fish passages at the Iron Gate dams could provide access of migratory fish to the upstream 900 km long stretch of the Danube and its major tributaries. This study was performed as a part of activities in project "Fish behaviour preparatory study at Iron Gate Hydropower dams and reservoirs" financed by European Investment Bank with the main goal to test telemetry techniques in the vicinity of Iron Gate dams. Fish tagging was performed with Vemco V16 TP acoustic tags, equipped with temperature and depth sensors. Seven Vemco VR 2W receivers were installed on 7 - 8 April 2015 downstream the Iron Gate II HPP, along Serbian and Romanian banks. One catfish (Silurus glanis), with total length about 2 m and total weight about 100 kg, was tagged on April 28th 2015. Additionally, one specimen of barbel (Barbus barbus) and one specimen of asp (Aspius aspius) were tagged in the same year on November 6th and 11th, respectively. Asp and barbel were detected only in short period after releasing while catfish records lasted from 28 April, 2015 till 13 February, 2017. One beluga sturgeon, which was tagged in 2013 in Borcea branch (Danube rkm 300), was recorded on receivers in the vicinity of Iron Gate II during 2015. This research was the first attempt to investigate behavior of different fish species in the vicinity of Iron Gate II. It also point to problems of collecting reliable data for fish behavior in this area and need to solved them.