Monitoring the status of wild populations in the Lower Danube River
Nowadays, due to the dams constructed at Iron Gates I and II, most of the wild populations of long-distance migratory sturgeons are confined to the Lower Danube River, as the large dams disrupt their migration routes from the Black Sea to former upstream spawning sites.
However, also populations of the native Danube freshwater sturgeons (Acipenser ruthenus, A. nudiventris and resident A. gueldenstaedti) are hindered in their migrations and their populations are fragmented by dams also above the Iron Gate gorge.
The International Commission for the Protection of Danube River (ICPDR) and the Food and Agricultural Organization (FAO) are committed to find a way to re-establish the river continuity by re-opening the migration corridor at Iron Gates. A feasibility study to construct a fish pass enabling sturgeons to pass over the dams is under discussion.
Meanwhile, the remnant wild populations are under surveillance by several research teams, in order to evaluate their status and ensure their survival in the Lower Danube. Key research institutions are: Danube Delta National Institute Tulcea, Romania; Danube Biosphere Reserve Vilkovo, National Academy of Sciences, Ukraine; Institute for Biodiversity and Ecosystem Research, Sofia, Bulgarian Academy of Sciences; Institute for Biological Sciences, University of Belgrade, Serbia.
One focus in Lower Danube activities lies on the documentation of the annual reproduction of the different species and the numbers and health of the caught yearlings (YOY = Young of the YEAR) allow to estimate the spawning success of each year. Also, sturgeons are tagged in order to track their migration and important habitats.
Similar activities are planned for the remaining freshwater populations of the Middle and Upper Danube.
The pictures below illustrate aspects from their activity
Young of the year Beluga sturgeons captured on 18 June 2011 in Danube River at rkm 123, tagged externally with Floy Fingerling Tags. Photo credit: Marian Paraschiv, Danube Delta National Institute Tulcea, Romania/ Sturgeon Research Group.
Young of the year beluga sturgeons captured in the Danube River at rkm 123 (July 7, 2011). Photo credit: Marian Paraschiv, Danube Delta National Institute Tulcea, Romania/Sturgeon Research Group.
Young of the year sterlet (up), stellate sturgeon (middle) and beluga sturgeon (down) captured in the Danube River at rKm 123 on July 6, 2004. Photo credit: Marian Iani , Danube Delta National Institute, Tulcea, Romania /Sturgeon Research Group.
Sterlet larva born in the Danube River and the drift net used to capture it in Danube River, rKm 310 (May 10, 2009). Photo credit: Radu Suciu, Danube Delta National Institute, Tulcea, Romania / Sturgeon Research Group.
Tagging beluga male Harald with satellite pop-up tag (Tămădău, Hatchery of Beluga Farm Group Ltd, May 26, 2009). Photo credit: Elena Taflan, Danube Delta National Institute Tulcea, Romania / Sturgeon Research Group.
Attaching satellite Pop-up tag to the back of beluga male Harald (Tămădău, Hatchery of Beluga Farm Group Ltd, May 26, 2009). Photo credit: Elena Taflan, Danube Delta National Institute,Tulcea, Romania / Sturgeon Research Group.
planting an acoustic tag to aquaculture reared young of the year beluga sturgeon, to be released and tracked in the Danube River (Tămădău, Hatchery of Beluga Farm Group Ltd, August 24, 2010). Photo credit: Radu Suciu – Danube Delta National Institute, Tulcea , Romania/ Sturgeon Research Group.
Communication activities - Fact sheets provided by WWF