Modifică dimensiunea fontului:
The Lower Danube is home to Europe's last wild, naturally-reproducing sturgeon populations; due to the multitude of habitats they use throughout their life, these ancient fish are an indicator of the quality of the environment.
Sturgeon survived the dinosaur age and all species - the beluga sturgeon, the starry sturgeon, the ship sturgeon and the diamond sturgeon - are listed as critically endangered on the International Union for Conservation of Nature's (IUCN) Red List, which is why the authorities and researchers are making efforts to preserve sturgeon stocks, based on a Regional Strategy for the Conservation and Sustainable Management of Sturgeon Populations in the Lower Danube River and the North-West Black Sea Region, approved in June 2013 during the CITES Regional Meeting in Tulcea.
As part of the project "Development of the Isaccea migratory fish monitoring station: sturgeon and mackerel" initiated by the Danube Delta Biosphere Reserve Administration in partnership with the Danube Delta National Research and Development Institute (INCDDD), the tagging of adult sturgeon with acoustic transmitters started in June this year, in order to monitor their route upstream the Danube and later back to the Black Sea.
The fish is caught on the Danube by professional fishermen from the Grindu commune, under the supervision of INCDDD Tulcea researchers.
"So far, 10 starry sturgeons have been captured, the largest being a five-kilogram female. They were all weighed, measured and photographed, and had a tiny fin fragment collected for molecular genetic analysis. In the end, they were fitted with acoustic tags and released back into the river," researcher Marian Paraschiv told AGERPRES.
The monitoring of this year's sturgeon juveniles went in parallel with the capture of adult individuals.
"The most important thing is that, after more than a decade, a young-of-year sturgeon was captured this July, a sign that this species is also starting to reproduce following the stocking actions conducted in the past," the INCDDD expert said.
Marian Paraschiv points out that sturgeon are some of the most interesting and complex fish species, with a lifespan that can exceed 100 years and that can reach impressive sizes - over five meters and 1,000 kilograms.
"These species emerged over 200 million years ago, according to some authors even 400 million years ago, and were widely present on all continents and in all seas of the Northern Hemisphere, from the Arctic to the tropics. The Lower Danube sturgeons are the only/the last naturally-reproducing wild sturgeon populations in the European Union, so that their conservation and protection require sustained efforts. INCDDD, in its capacity as CITES Scientific Authority, has the role of monitoring the status of wild sturgeon populations and recommend protection measures that are required at national and regional level," the researcher said.
According to him, the special importance of Danube sturgeons has been mentioned as early as antiquity by writers Herodotus (484 - 425 BC) and Strabo (63 BC - 21 AD), the latter noting that "sturgeon fishing is customary in the north of Scythia, and they are as big as dolphins". The inhabitants of Histria, a Greek colony port to the Black Sea founded 2,200 years ago, were allowed to capture sturgeons at the mouths of the Danube and export the salted fish to Greece and Rome tax-free. Beluga sturgeon and diamond sturgeon made most of the fish cargo.
In the Middle Ages and until the end of the 18th century, sturgeon represented an inexhaustible resource of the Danube. Especially the beluga sturgeon was captured throughout the river's Romanian sector, from the mouths of the Danube to the Iron Gates, on the Middle Danube and upstream to Bavaria. Sturgeons were also found in abundance in the Danube tributaries - Drava, Sava, Tisa, Mures, Siret or Prut. In the 12th - 15th centuries, sturgeons were exported from the Danube area to Poland.
"In 1409, voivode Mircea the Elder ordered all the locals of the villages along the Danube to catch sturgeons three days a year for the princely Court. Italian monk Niccolo Barsi, who visited Moldova between 1633 and 1639, (...), mentioned that the fishermen used to bring to Chilia 1,000 - 2,000 sturgeons every day, and that from here they were being exported to Constantinople, Poland and Hungary, reports researcher Bacalbasa-Dobrovici. In 1690, Austrian general Marsigli wrote that around 50 - 100 beluga sturgeons were caught every day near the island of Ada-Kaleh (meanwhile submerged underwater after the construction of the Iron Gates hydroelectric power station. In 1762, French consul Peysonnel reported that around 25,000 beluga sturgeons were caught annually in Chilia," said researcher Marian Paraschiv.
Starting with the 16th century, the town of Galati entered a blooming period, being known as an important sturgeon fishing and market center. An Italian monk, Barsi, mentions Galati as having a great abundance of sturgeon and caviar. In 1652, English traveler Robert Bargrave also noted: "Sometimes they catch fish so big that it takes 6-8 oxen to lift them together with the trap".
During the communist regime, between 1948 and 1989, the centralized economy did not consider the exploitation of a fishery based on ecological criteria. Sturgeon fishing was usually done in Sfantu Gheorghe - Tulcea County, and the fish were intended for party leading officials or were exported. The situation did not visibly improve after the fall of communism either. The rising number of fishing permits issued resulted in a lack of information on legal catches and an even more intense fishing activity, according to the researchers.
Overfishing, the pollution of the Danube, the destruction of habitats and the damming of the river were the main causes for the severe decline in sturgeon populations. Thus, alone the construction of the Iron Gates II dams (milestones 864 km and 943 km), which had no passages for migratory fish, cut to half the migration route of these species that once reached beyond Bratislava (milestone 1,850 km) and up to Regensburg (milestone 2,400 km).
"The special value of sturgeon and their sensitivity to changes in natural habitats, as well as the rapid decline in sturgeon populations, prompted the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) to include in 1998 sturgeon species in Appendices I (2 species) and II (24 species). Also, the IUCN has declared all sturgeon species as critically endangered.
"With the establishment of the Danube Delta Biosphere Reserve Administration in 1990, and under the supervision of CITES, illegal sturgeon fishing and trade has gone down, but even so, over-exploitation called for a set of measures for the conservation and sustainable management of wild sturgeon stocks that reproduce in the Danube," states researcher Marian Paraschiv.
Consequently, in 2006, the Ministries of Environment and Agriculture issued Joint Order 330/262 prohibiting commercial sturgeon fishing and setting in place repopulation programs with sturgeon fingerlings from species whose reproduction in the natural environment is deficient.
The conservation measures were extended for an indefinite period in 2021, by order of the Minister of the Environment.
Considering that sturgeons are anadromous fish, that is, they spawn in freshwater and live in the sea, all the other Lower Danube countries - Serbia, Bulgaria and Ukraine - have banned commercial fishing of these species, considered iconic for the river. AGERPRES (RO - author: Luisiana Bigea, editor: Georgiana Tanasescu; EN - editor: Simona Klodnischi)
The content of the www.agerpres.ro website has the exclusive purpose of public informing.
All the information published on this website by AGERPRES is protected by relevant legal dispositions.
It is forbidden to copy, reproduce, recompile, decompile, distribute, publish, display, modify, create derived components or products or full services, as well as any exploitation of the site's content.
The use of the Comments section entails your obligation to respect the AGERPRES terms and conditions in regards to the publishing of comments on the www.agerpres.ro.