Posted on April, 18 2018

With so many of their ancient migration routes blocked by dams and other obstacles, sturgeon species are battling for survival. And a wave of new dams planned for the Balkans and Danube basin could spell doom for what is already the world’s most endangered fish.

But not if WWF and the World Sturgeon Conservation Society (WSCS) can help it.

On World Fish Migration Day, the two conservation organizations launched the Vienna Declaration on Global Sturgeon Conservation – 22 recommendations to decisions makers from sturgeon scientists and conservationists to ensure the survival of these remarkable fish.

Sturgeons only live in the northern hemisphere and have been subjected to overfishing and other human-made pressures for decades, bringing them to the brink of extinction.

Dams have been one of the main factors in the collapse of the sturgeon’s global population as they have cut off access to many sturgeon spawning grounds, while also making these highly prized fish more vulnerable to poaching.

Old fishermen tell stories about the impact on sturgeons of the construction of the Iron Gates dam on the Danube: about how they were confusedly swimming along the dam walls trying to find a way upstream to their historic spawning grounds near Vienna and even further upstream in Germany. The Iron Gates stopped their migrations, while fishermen with cranes hauled them out of the river in large quantities.

But those days of plenty are long gone. The few sturgeons left in the Danube can still find no way through, under or over this insurmountable barrier.

The Vienna declaration calls for countries to greatly reduce the negative impact of dams on sturgeon rivers, including by ensuring old facilities are passable both upstream and downstream with fish passages for large migratory species. Modern modeling tools allow management authorities to tailor the water and sediment discharge for each river and ecosystem, so that it benefits people and nature. Continuous monitoring must also be put in place, to make sure the measures are working and if needed, the approach is adapted accordingly.

The declaration also calls for the removal of outdated dams, which no longer are effective and do not justify a refit with a fish pass.

Along with its recommendations around dams, the Vienna Declaration also highlights a variety of other actions that decision and policy makers should immediately take to limit threats to the world’s remaining wild sturgeon populations and support their natural reproduction.