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IUCN Red List reassessment reveals further decline of sturgeons and paddlefishes

Published online by Cambridge University Press:  13 January 2023

Leonardo Congiu
Affiliation:
University of Padova, Padova, Italy. [email protected]
Joern Gessner
Affiliation:
Leibniz-Institute for Freshwater Ecology and Inland Fisheries, Berlin, Germany.
Arne Ludwig
Affiliation:
Leibniz-Institute for Zoo and Wildlife Research, Berlin, Germany

Abstract

Type
Conservation News
Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence CC BY 4.0.
Copyright
Copyright © The Author(s), 2023. Published by Cambridge University Press on behalf of Fauna & Flora International

Sturgeons have survived epochal ecological changes but are succumbing to the greed of Homo sapiens. A Red List update by the IUCN Sturgeon Specialist Group on 21 July 2022 revealed that the already precarious state of sturgeon populations has further declined.

The Chinese paddlefish Psephurus gladius, endemic to the Yangtze River, is extinct. Another species endemic to the Yangtze River, the Dabry sturgeon Acipenser dabryanus, is categorized as Extinct in the Wild as all animals observed in nature are from restocking programmes. European species are faring poorly: the eight species, although under protection since 1992, are either Endangered or Critically Endangered. One of these, the ship sturgeon Acipenser nudiventris, is extinct in the Danube. The situation of the North American species is slightly better than that of the Eurasian species, as a result of more timely conservation efforts, but their condition has also worsened.

The causes of the disappearance of sturgeons are well known. The first is illegal fishing: although fishing is banned in most of the species’ ranges and although > 500 t of caviar are produced annually in aquaculture, poaching is still a serious problem. The second is the loss of migration corridors and habitats because of the development of hydropower. Many species of sturgeons are anadromous and all species migrate long distances: they need to swim upstream during the spawning period, lay their eggs in suitable habitat and freely return to the sea. Finally, pollution of waterways, and changes of discharge and temperature as a result of climate change, and the spreading of invasive species are also threats.

But there remains hope. In the Caucasus, in the Rioni River, the ship sturgeon has reappeared after years of absence (Beridze et al., 2021, Oryx, 55, 9). The Adriatic sturgeon Acipenser naccarii has shown sporadic reproduction in the Po basin (Congiu et al., 2021, Oryx, 55, 816) and has therefore been recategorized from Extinct in the Wild to Critically Endangered. Pseudoscaphirhynchus hermanni of the Amu Darya has been rediscovered after almost 20 years (Sheraliev et al., 2021, Oryx, 55, 332). These are signs that if adequate protection measures are put in place, sturgeons will benefit from them. The Pan European Action Plan approved by the Bern Convention in 2018 provides a guideline for the conservation of sturgeon species. If we are able to organize and support international recovery projects based on the scientific knowledge acquired in the last few decades, we can still hope to save sturgeon species from extinction.

We thank all experts of the Sturgeon Specialist Group and the IUCN assessment team for their contributions and support.

Footnotes

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Also at: IUCN SSC Sturgeon Specialist Group