海角大神

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.聽

The fish, some of 1,000 juvenile Russian聽sturgeon聽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.

鈥淭he situation for the聽sturgeon聽population is not good,鈥� says Dr. Paraschiv, a researcher from the聽Danube Delta National Institute聽for Research and Development in聽Tulcea, Romania. 鈥淎ll the species are critically endangered. The Russian聽sturgeon聽is the most endangered; it鈥檚 close to extinction.鈥�

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.聽A century ago, beluga聽sturgeon, known as a source of high-grade caviar, could still be found as far upriver as Vienna. Today,聽the Russian聽sturgeon聽is among the last four聽sturgeon聽species still found in the river. Romania and neighboring Bulgaria have the only viable populations of wild聽sturgeons聽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 鈥渕ost critical sector that we have to protect,鈥澛爏ays Apostolos Apostolou, an assistant professor at the Institute of Biodiversity and Ecosystem Research at the Bulgarian Academy of Sciences.聽

鈥淚t鈥檚 not too late 鈥� it鈥檚 about five minutes to midnight, but I鈥檓 optimistic because of these restockings and the prohibition on fishing,鈥� he adds. 鈥淭hings are changing. Slowly, but they are changing.鈥�

Dammed if you do

Rivers, like most natural habitats, have been strongly affected by human intervention, and聽sturgeon聽populations, like those of many other migratory species, have plummeted drastically in recent decades, with overfishing, dams, and river pollution badly affecting population sizes.

鈥淪turgeons聽pose the ultimate challenge to river basin managers, as, really, all human impacts on the ecosystem are featured in the decline of the聽sturgeon聽populations,鈥� says Thomas聽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鈥檚 sturgeon population. 鈥淲e鈥檙e talking overfishing, degradation of habitat, pollution, migration barriers, all of these are really affecting the聽sturgeon.鈥�

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,聽鈥渕aking them the most threatened group of animals on the IUCN Red List of Threatened Species.鈥�

In the past, a聽sturgeon聽could, with one catch, make a local fisherman鈥檚 year. Yet many countries now prohibit sturgeon fishing. Romania enacted a ban in 2006, though underground trade remains. Without economic alternatives it鈥檚 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聽sturgeon聽populations has been, and continues to be, caused by dams, hydropower plants, and other man-made barriers.

鈥淚t鈥檚 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,鈥� 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聽S茅lune 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.聽

鈥淭he removal of the Vezins Dam signals聽a revolution in Europe鈥檚 attitude towards its rivers,鈥� Roberto Epple, president of European Rivers Network, told the WWF. 鈥淚nstead of building new dams, countries are rebuilding healthy rivers and bringing back biodiversity.鈥�

Dams blocking rivers in other countries have also been removed in recent years. However, a recent聽study聽found that聽just one-third of the world鈥檚 longest rivers 鈥� those over 1,000 kilometers (620 miles) in length 鈥� remain free-flowing today.

Repopulating efforts

Given the cost involved in dam removal, environmentalists and policymakers are trying other means.聽Hence the restocking efforts.聽

Standing beside the flowing Danube, Dr. Paraschiv says they鈥檝e released more than half a million juvenile聽sturgeon聽over the past 15 years, with tens if not hundreds of thousands also released in Bulgaria. One-year-old聽sturgeon聽are far less likely to be killed by predators, he adds, so they have a greater chance of reaching maturity and returning to spawn. 鈥淔urther restocking efforts will take place next year and in 2021,鈥� he adds. 聽

鈥淚n the case of Russian聽sturgeon, any specimen that survives is important because the level of population is very low,鈥� says the WWF鈥檚 Ms. Munteanu.

In June 2018, all 10 countries along the Danube signed onto a three-year coordinated effort to conserve endangered migratory fish species.聽Last fall they published an action plan for all European聽sturgeon聽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 鈥渏ust a little kick so that it will start moving,鈥� says Mr. Friedrich, the fisheries biologist.

鈥淔or聽sturgeon, this is the first truly transnational project, and it鈥檚 only a small step,鈥� he adds. 鈥淔ish don鈥檛 stop at national borders. These fish like to migrate over several thousand kilometers, and without a multilateral approach there鈥檚 no possible way to save the species.鈥�

Efforts are now underway to localize and map the fish鈥檚 habitats in order to conserve and protect the species. Another project, supported by the European Commission, involves the potential construction of a fish pass 鈥� which would allow migrating聽fish passage聽beyond the dam 鈥� at the Iron Gates.

鈥淔rom a technical point of view it鈥檚 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,鈥� says Mr. Friedrich.

Still, he鈥檚 clear that we can鈥檛 ignore the challenge: 鈥淲e 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.鈥�