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Numerous species of migrating fish once traveled the length of the Danube, the second-longest river in Europe. A century ago, beluga sturgeon, known as a source of high-grade caviar, could still be found as far upriver as Vienna. Today, the Russian sturgeon is among the last four sturgeon species still found in the river.
More than 85% of sturgeon species around the world are now classified as being at risk of extinction, making them the most threatened group of animals on the International Union for Conservation of Nature Red List of Threatened Species. Sturgeon populations have plummeted drastically in recent decades due to overfishing, dams, and river pollution.
Now, advocates are taking action. Many countries now prohibit sturgeon fishing. Hundreds of thousands of juvenile sturgeon have been released into the Danube over the past 15 years. And some countries are considering removing man-made obstacles, like dams, to help migratory species.
“It’s not too late – it’s about five minutes to midnight, but I’m optimistic because of these restockings and the prohibition on fishing,” says Apostolos Apostolou, a researcher in Bulgaria. “Things are changing. Slowly, but they are changing.”
Standing knee-deep in the murky waters of the Danube River, Marian Paraschiv slowly tips a basket of squirming fish into the slow-moving waters.
The fish, some of 1,000 juvenile Russian sturgeon brought to the river from a nearby fish farm, are part of a restocking event that environmentalists hope will, in a small way, contribute to the preservation of an iconic species little changed since the time of dinosaurs. It could also help in the fight to save other migratory river species that have been badly affected by industrial developments, damming, and overfishing.
“The situation for the sturgeon population is not good,” says Dr. Paraschiv, a researcher from the Danube Delta National Institute for Research and Development in Tulcea, Romania. “All the species are critically endangered. The Russian sturgeon is the most endangered; it’s close to extinction.”
Numerous species of migrating fish once traveled the length of the Danube, the second-longest river in Europe, which passes through 10 countries before emptying into the Black Sea. A century ago, beluga sturgeon, known as a source of high-grade caviar, could still be found as far upriver as Vienna. Today, the Russian sturgeon is among the last four sturgeon species still found in the river. Romania and neighboring Bulgaria have the only viable populations of wild sturgeons left in the 28-nation European Union.
For now, the southernmost portion of the river is the most viable habitat, a 700-kilometer (430-mile) stretch below the so-called Iron Gates, a trio of gorges lined with hydroelectric plants that mark the boundary between Serbia and Romania. This is the “most critical sector that we have to protect,” says Apostolos Apostolou, an assistant professor at the Institute of Biodiversity and Ecosystem Research at the Bulgarian Academy of Sciences.
“It’s not too late – it’s about five minutes to midnight, but I’m optimistic because of these restockings and the prohibition on fishing,” he adds. “Things are changing. Slowly, but they are changing.”
Dammed if you do
Rivers, like most natural habitats, have been strongly affected by human intervention, and sturgeon populations, like those of many other migratory species, have plummeted drastically in recent decades, with overfishing, dams, and river pollution badly affecting population sizes.
“Sturgeons pose the ultimate challenge to river basin managers, as, really, all human impacts on the ecosystem are featured in the decline of the sturgeon populations,” says Thomas Friedrich, a fisheries biologist at the University of Natural Resources and Life Sciences in Vienna who is involved in efforts to try to revive the Danube’s sturgeon population. “We’re talking overfishing, degradation of habitat, pollution, migration barriers, all of these are really affecting the sturgeon.”
More than 85% of sturgeon species around the world are now classified as being at risk of extinction, the International Union for Conservation of Nature reported in 2010, “making them the most threatened group of animals on the IUCN Red List of Threatened Species.”
In the past, a sturgeon could, with one catch, make a local fisherman’s year. Yet many countries now prohibit sturgeon fishing. Romania enacted a ban in 2006, though underground trade remains. Without economic alternatives it’s proving hard to persuade some fishing communities to give up the catch, according to those involved in the effort.
Even so, much of the damage to sturgeon populations has been, and continues to be, caused by dams, hydropower plants, and other man-made barriers.
“It’s important to keep this last 700 kilometers [below the Iron Gates] free-flowing, because if we shorten again the length of the free-flowing Danube, then anything we do is for nothing,” says Cristina Munteanu, a national coordinator for the Save the Danube Sturgeon Project at World Wide Fund for Nature in Romania.
Beyond efforts to reduce overfishing and restock populations, some countries are also looking at removing man-made obstacles, in part to help migratory species. In June, France began dismantling a 120-foot-high dam on the Sélune River, marking the start of the biggest dam removal project in Europe to date. The demolition, along with the removal of a second dam within the next two years, is expected to open up about 55 miles of the river and help bring back salmon, eels, and other species.
“The removal of the Vezins Dam signals a revolution in Europe’s attitude towards its rivers,” Roberto Epple, president of European Rivers Network, told the WWF. “Instead of building new dams, countries are rebuilding healthy rivers and bringing back biodiversity.”
Dams blocking rivers in other countries have also been removed in recent years. However, a recent study found that just one-third of the world’s longest rivers – those over 1,000 kilometers (620 miles) in length – remain free-flowing today.
Given the cost involved in dam removal, environmentalists and policymakers are trying other means. Hence the restocking efforts.
Standing beside the flowing Danube, Dr. Paraschiv says they’ve released more than half a million juvenile sturgeon over the past 15 years, with tens if not hundreds of thousands also released in Bulgaria. One-year-old sturgeon are far less likely to be killed by predators, he adds, so they have a greater chance of reaching maturity and returning to spawn. “Further restocking efforts will take place next year and in 2021,” he adds.
“In the case of Russian sturgeon, any specimen that survives is important because the level of population is very low,” says the WWF’s Ms. Munteanu.
In June 2018, all 10 countries along the Danube signed onto a three-year coordinated effort to conserve endangered migratory fish species. Last fall they published an action plan for all European sturgeon species. Restocking events like the one in Romania are a key part of that effort.
The hope for this project is to give the ball “just a little kick so that it will start moving,” says Mr. Friedrich, the fisheries biologist.
“For sturgeon, this is the first truly transnational project, and it’s only a small step,” he adds. “Fish don’t stop at national borders. These fish like to migrate over several thousand kilometers, and without a multilateral approach there’s no possible way to save the species.”
Efforts are now underway to localize and map the fish’s habitats in order to conserve and protect the species. Another project, supported by the European Commission, involves the potential construction of a fish pass – which would allow migrating fish passage beyond the dam – at the Iron Gates.
“From a technical point of view it’s already really challenging. So it has to be probably some sort of combination of fish lift and guiding structures in the river. It will be quite tricky and it will be quite expensive,” says Mr. Friedrich.
Still, he’s clear that we can’t ignore the challenge: “We have these animals that are 200 million years old, and it took humanity 200 years to drag them toward extinction, in some cases already to extinction.”