They release 1.6 million sturgeons into the Danube, which will be raised in floating nurseries in the upper reaches of the river. The European Commission has called on member states to step up efforts to tackle poaching and illegal trafficking to protect the continent's few remaining sturgeon stocks. Although they outlived the dinosaurs, today they are the most endangered group of animals in the world. Stoyan Mihov from the environmental protection organization WWF spoke to FAKTI on the topic.
- Mr. Mihov, why is the sturgeon important for the Danube River?
- Sturgeons are emblematic of the Danube River, not only because they are unique in the world of fish with their size – the moruna reaches over 6-7 meters in length and weighs over a ton, but also because they have been a very important natural resource for the human communities along the river during the last 10 thousand years. But sturgeons are important for another reason - because of their high demands on water quality, temperature, continuity of flow and natural seasonal fluctuations in the water level of the river. They are a living indicator of the state of the river. When their population decreases, it means that the condition of the river is deteriorating.
- How does hydropower development affect biodiversity in the river?
- The hundreds of hydroelectric power plants (HPPs) built along the main course of the Danube in the last century have drastically worsened the river's ecological condition and severely affected migratory fish populations. Many Danube fish species carry out breeding migrations – i.e. they live in the lower reaches of the river or in the Black Sea and once a year - usually in the spring or autumn - they go far upriver where they spawn in the fast, oxygen-rich waters. After hatching, the small fish follow the current and reach the lower reaches of the river and the Black Sea, thus closing their life cycle. Once multiple hydroelectric dams are built, this cycle is broken, the fish cannot overcome the dam walls and cannot reach the traditional spawning grounds.
Thus they are forced to spawn in inappropriate places where it dies or is not spawned at all.
Thus, fish populations disappear from the upper reaches of the river and drastically decrease in the lower reaches. Hydroelectric power plants have another negative impact – they change the natural “pulse“ of the river, under natural conditions the river level slowly rises or falls over days or weeks following rainfall or snowmelt. Sturgeons and other fish species are very well adapted to these conditions and can anticipate them, their reproductive cycle is linked to these changes. However, after the construction of the HPP, the “pulse” on the river is extremely accelerated and uneven, because the river level is already dependent on the consumption of electricity, and within 24 hours the river level can artificially rise or fall more than one meter, which is catastrophic for fish such as sturgeons and interrupts their reproduction and migration.
- Nowadays, the last wild sturgeon populations in Europe live in the lower reaches of the Danube River - on the border between Bulgaria and Romania. Why did it happen?
- The lower course of the Danube between Serbia, Bulgaria, Romania and Ukraine is the last, long enough, free-flowing section of the river - more than 850 km, in which no barrier has yet been built - a large hydroelectric power station or a dam wall. Although a large part of the sturgeon breeding grounds have remained behind the walls of the "Iron Gate" HPP. 1 and 2, still some sturgeon fish manage to reproduce, although in very low numbers.
Unfortunately, in the public space we hear more and more often about the revival of projects for the construction of hydro nodes on the Danube, which were rejected even in the “socialist times”, due to environmental considerations and economic disadvantages – “Nikopol Hydroelectric Plant - Turnu Magurele“ – near the town of Belene, and the Silistra Hydroelectric Plant – Kalrash“, which will completely destroy the last remaining sturgeons in the river. Not to mention the other environmental and economic damage and the need to evacuate cities and villages.
- The loss and fragmentation of their habitats… Is this the scariest thing about their existence?
- The reasons for the disappearance of sturgeons are really complex, but they are all the result directly or indirectly of human activity. The leading cause is the destruction of their habitats, but overfishing of sturgeons in the past and intensive poaching today have also contributed greatly to the sharp decline in populations. We are talking about more than 95%. Poaching is an extremely serious problem because it destroys the few remaining individuals that enter the river to breed. Every year, the Bulgarian Border Police and the Executive Agency for Fisheries and Aquaculture confiscate hundreds of suckers in the Danube with thousands of hooks, a cruel fishing method specially adapted to poaching large sturgeons during their migration.
The hot spots, with the most confiscated infants, are mostly around the town of Kozloduy and around the town of Svishtov.
Rapid climate change makes recovery of sturgeon populations very difficult. The biological features of sturgeons that have helped them survive for millions of years, such as a long life cycle (over 100 years) and slow sexual maturation (usually after 7-16 years of age), today prevent them from adapting to conditions of rapid climate change and they are losing the battle for their survival.
- What does the LIFE-Boat project…
involve - LIFE Boat for Sturgeons is a large international project in which WWF also participates – Bulgaria, which aims to support the conservation and restoration of sturgeon populations along the entire course of the Danube River. It involves the construction of several sturgeon breeding stations, the largest of which will be built on a ship in Austria. In these stations, 4 species of sturgeon will breed and over a million young will be released in the next few years into the Danube River to support the damaged populations.
- What will we do in Bulgaria?
- In the Bulgarian-Romanian section of the Danube River, all artificially hatched sturgeon fish migrating from the Black Sea to the Danube River will be released – these are the grayling, the trout and the Russian sturgeon. Our role in Bulgaria is to find the suitable places for resettlement and to organize the release of the small fish. We are working with the Bulgarian fishing communities along the Danube River and the Black Sea, to help us trace the path of the young to the sea on the one hand, and on the other hand to remind them how important it is to release all the sturgeon caught so that a day, when the sturgeons have already grown, to return to the river and restore the vanishing fishing livelihood.