Release of 250 European sturgeon into the Rhine

Thanks to the breeding of descendants from the last wild sturgeon in France and Germany, it is now possible to release these fish back into the Rhine and study what is needed for the species to make a permanent return.

The sturgeon is an enormous fish, capable of growing over 3 m long and weighing up to 150 kg. Covered in bony plates instead of scales, with a pointed head and barbels around its mouth, it appears almost prehistoric and indeed, sturgeon have existed in our waters for tens of millions of years. Today, it is estimated that fewer than 1,000 adult specimens of this prehistoric species remain in the wild.

Driven to extinction by humans

The extinction of the European sturgeon, once the largest migratory fish in the Netherlands, is largely due to human activities such as overfishing, intensive shipping, the laying of canals and pollution. Additionally, the construction of dams and locks has blocked the free passage of sturgeon between the sea and rivers. Sturgeon spend most of their lives at sea, but breed in large rivers where the young grow until they are ready to return to the sea.

The restoration and preservation of free-flowing rivers is essential not only for the survival of the sturgeon but also for other migratory fish and to preserve riverine ecosystems. If the river-sea connection is restored for the large sturgeon, smaller migratory fish, such as salmon, eel, twait shad, whitefish and stickleback, will also be able to make the crucial journey between fresh and saltwater.

Restoration programme and conditions for success

Since 2004, ARK Rewilding Netherlands, the World Wildlife Fund (WWF-NL) and Sportvisserij Nederland have been working together on the reintroduction of the sturgeon. Since 2023, the sturgeon programme has been part of the Interreg programme 'The Rhine Connects’ (Der Rhein verbindet). Farmed sturgeon were previously released into the Rhine in 2012 and 2015, and into the Biesbosch in 2023.

Monitoring via transmitters has shown that some sturgeon have made it to the North Sea via the port of Rotterdam. Occasionally, North Sea fishermen catch sturgeon, which they then release. Reports of sturgeon catches provide important information on how these animals are faring. In 2024, young sturgeon will once again be released into the Millingerwaard (Gelderland). This location was chosen to provide comparative data with previous releases.

The young sturgeon (1.5 years old, about 30 cm long and weighing 100 gr) are equipped with special identification chips, location transmitters and predator tags. These will soon provide valuable data on their survival chances, migration routes and return to the Rhine for reproduction. This information is crucial in determining whether a large-scale reintroduction of the European sturgeon is feasible, and if so, the best approach to achieve this.

Challenges and future prospects

Despite these efforts, the future of the sturgeon remains uncertain. The number of farmed sturgeon available is limited. Therefore, it is necessary to expand breeding capacity, preferably along the Rhine. Moreover, several ecological conditions must be met for the successful return of the sturgeon, including:

• Free passage between sea and river, with unimpeded upstream migration for fish.
• Natural river flow and clean gravel beds for spawning.
• Sufficient food and suitable living conditions for young sturgeon.
• Safe river conditions for fish, including protection from ship propellers and safe passageways around weirs, locks and hydroelectric plants.
• A healthy brackish water zone as a transition between fresh and saltwater.

Release of 250 sturgeon

On 16 August 2024, some of the 250 sturgeon were released in the presence of dignitaries from the German state of North Rhine-Westphalia and from the Netherlands. A group of children, along with WWF rangers, assisted in the release of the sturgeon. The release took place at the tea garden in Millingen aan de Rijn.