The Upper Drava River is completely passable for migrating fish
Today VERBUND put two modern fish bypasses into operation near the Drava River power plants Paternion and Kellerberg. Both hydropower plants have been providing renewable electricity from hydropower since their construction in the 1980s, and with this are making a valuable contribution towards attaining the climate goals. However, until now the power plants have formed an insurmountable obstacle for fish with their migratory nature.
With the new fish bypasses inaugurated today, technically and ecologically sophisticated structures were created which will enable fish and other aquatic fauna in the river to circumnavigate the power plants. In doing so, the fish overcome an elevation difference of nearly ten metres in each case.
From Rosental to the source: approx. 65 % of the Drava River within Austria is continuously navigable for fish.
"With the two new fish bypasses in Paternion and Kellerberg, in connection with the fish bypasses constructed in recent years near the VERBUND power plants in Villach and Rosegg, the Drava River has now for the first time in decades become completely navigable for fish over a stretch of 135 kilometres", explains Karl Heinz Gruber, Managing Director of VERBUND-Wasserkraft. "This means that not only was an originally connected habitat restored from the Feistritz im Rosental power plant all the way up to the source, but in addition, this made a significant contribution towards maintaining biological diversity in the Drava River. By 2021 we will have made the entire domestic section of the Drava navigable for fish over a distance of more than 200 kilometres", stated Karl Heinz Gruber on the occasion of today's inauguration of the new fish bypasses.
Record structures: Europe's tallest fish bypasses are being created in Carinthia
VERBUND has constructed six fish bypasses on the Drava to date, including Europe's as yet tallest fish bypass at the Schwabeck power plant, with an elevation difference of 21 metres. In the coming years, the still remaining and largest Drava power plants in Feistritz, Ferlach, Annabrücke and Edling (Völkermarkter Stausee reservoir) will be equipped with sophisticated fish bypasses. When completed, the one in Annabrücke will overcome an elevation difference of 25 metres and once again establish a European record.
By 2021 VERBUND will have invested around 30 million euros in the ecological enhancement of the habitats in Carinthia alone.
Proof of functionality
In the Drava River, the fish bypasses are especially important for so-called mid-distance migrants such as the nase or the barbel, which undertake extensive upstream spawning migration. But also the Danube salmon, the largest fish species in the Drava at a length of about one metre, can swim through the bypasses without a problem.
That the new bypasses really do work is verified by means of ecological fish monitoring. A form of video monitoring developed in cooperation with the University of Natural Resources is used here, which records visual images via FishCam of all "users" of the bypasses for subsequent evaluation.
The current monitoring analysis for the fish bypass at the Schwabeck power plant speaks for itself: All of the Drava's dominant fish species swim through the migration channels. Altogether, since the end of 2015 more than 36,500 videos of migrating individual fish or shoals (bleak and schneider shoals) have been recorded. About 20,000 individual fish and about 10,000 schooling fish (mostly bleaks and schneiders) ascended by means of the fish bypass, and about 1,800 fish descended.
All 23 occurring fish species specific to the dominant type (dominant species and typical accompanying species), as well as weak-swimming small fish and small animals have successfully found and passed through the fish bypass. The fact that not only fish, but frequently also otters, beavers and crustaceans have been filmed by the FishCam during their migration, speaks for the high ecological quality of the structures.