Meteors, dams, poaching, pollution and even climate change haven’t defeated sturgeon yet. Of course, these are all – well, minus the meteors – real dangers which sturgeon still have to face daily, and having survived it all for so long, it is safe to say that these fish can teach us a bit about resilience.

Some 200 milion years ago, dinosaurs roamed the Earth and sturgeon swam its waters. Fast forward two eras and the dinosaurs are gone, while sturgeon, although  more critically endangered than any other group of species can still be found in America, Asia and Europe.

And thanks to conservation efforts around the world involving local fishermen and consumers, and transboundary collaboration between enforcement authorities, their future does not seem so glum.

In 2020, a sterlet was caught in Slovenia, in the Drava River, just before Christmas. Workers at the Formin Hydropower Plant were doing their maintenance work when they discovered a rare visitor, a species of sturgeon which hadn’t been seen in the Drava River since 2001[1].

No face, no name, no number

Was this a loner or just the first of a bigger group? No one knows. The workers who caught the fish quickly released it back into the Drava, after taking photos.  Since there is no monitoring program in place, there was no one to call or check if the sterlet had an internal tag, let alone collect DNA samples. So where the fish was coming from and where it was going still remains a mystery. One, however, that the REVIVO specialists would like to uncover.

The area on the Drava where the hydropower plants are located is known for big pools which were – and might still be – used as habitat by migratory fish. Uncovering this sterlet’s  secrets could be done using  telemetry - tracking animals from a distance, using sounds - like the the European Tracking Network recommends. Specialists at the REVIVO Institute are planning to release over 100.000 sterlets in the Mura River  in the next years.  These will be tagged and monitored, as part of the new project LifeBoat4Sturgeons, 30 of which will be equipped with radio transmitters and tracked for 18 months. In the MEASURES project, almost 9000 sturgeon were released in different parts of the Danube River, in Romania and Hungary but, although tagged, none have this kind of device.

A new trend?

Sturgeon are making a comeback in Georgia, too, in the Rioni River. In 2020, anglers were surprised to catch two ship sturgeon in the river: one in mid-March and one in April. Surprised not because these were sturgeon, since the river is home to several species, among which,  the world’s only population of Colchic sturgeon (Acipenser [persicus] colchicus), but because the ship sturgeon had not been spotted for years.

Here too, scientists lack the necessary information about habitats and spawning, and time might be running out. According to Fauna & Flora International experts, a proposed  development of several hydropower plants on the Rioni could dramatically change the habitats ship sturgeon are trying to return to.

Despite the dangers, sturgeon do not seem to be throwing in the towel yet. And util they do, experts around the world need to coordinate and intensify conservation efforts. The MEASURES Regional Strategy for the Danube Corridor which will be published by the end of the project is one such example.

[1] Govedič M. in Friedrich T., 2018

Foto: Patrik Petrovič