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Extinction of a megafish: Can this spark action to save other migratory freshwater species? (commentary)

  • The Chinese paddlefish, recently declared extinct by researchers, was likely the world’s longest freshwater fish – as well as one of the oldest, swimming the earth’s rivers since the time of the dinosaurs.
  • It’s too late for this species, but there’s still time to save many of the world’s remaining migratory fish.
  • Parties to the Convention on Migratory Species – who will meet in Gandhinagar, India, from February 15 to 22 – must address the growing threats to migratory freshwater fish, argues William Darwall, Head of the Freshwater Biodiversity Unit, IUCN Global Species Programme.
  • This post is a commentary. The views expressed are those of the author, not necessarily Mongabay.

The extinction of the Chinese paddlefish, announced by researchers in January 2020, is entirely the result of human impacts on the Yangtze River over the last 50 to 60 years. This tragic event serves to highlight the challenges facing many of the world’s migratory freshwater fish species.

Many of these species could still be saved if we act now to reconnect the world’s fragmented rivers.

Reported to have reached up to 7 meters (about 23 feet) in length, the Chinese paddlefish was likely the world’s longest freshwater fish. It is certainly one of the oldest, swimming the earth’s rivers since the time of the dinosaurs.

Although it is too late for this unique ‘river monster,’ the remaining 1,200 or so migratory fish species need our attention. Some of these fish travel thousands of miles along the world’s great rivers to spawn, and dams represent a serious threat to their survival, as was recently documented in a report co-authored by the IUCN. Today, only a third of the world’s great rivers remain free flowing from their source to the sea.

Considerable research suggests that the Gezhouba Dam on the Yangtze River is likely to have been the final nail in the coffin for the Chinese paddlefish, tragically preventing the species from reaching its spawning grounds. There was no way for the fish to pass this dam.

As the only global convention specializing in the conservation of migratory animals, the Convention on Migratory Species (CMS) offers hope for migratory fish, helping countries collaborate to strengthen global conservation efforts to protect these international travelers.

The loss of the Chinese paddlefish is all the more poignant in view of CMS’s next meeting, from February 15 to 22 in Gandhinagar, India. The paddlefish was one of the first species listed in the Convention, and is now the first to go extinct.

In Gandhinagar, the IUCN and partners will share solutions from the Global Swimways project, supported by the Cambridge Conservation Initiative, to help countries address the growing threats to migratory freshwater fish. The project aims to connect fish, rivers, and people globally using the new concept of “Swimways” — paths that fish migrate along, similar to the flyways concept that has helped protect migratory birds for more than 80 years.

Parties to the Convention must act now to ensure the survival of the many lesser-known — yet equally impressive — migratory fish, such as sturgeons, mahseer, and the South American catfishes, as well as more familiar species such as salmon and eels. Transboundary mechanisms are also urgently needed for countries not yet signed up to the Convention, such as those sharing the Mekong River, where migratory fish species are under great pressure.

We also need to learn more about the world’s freshwater fish species if we are to avoid further losses. As highlighted by the researchers who tried in vain to find the Chinese paddlefish, we still know very little about the majority of freshwater fish species in the Yangtze. The IUCN Red List of Threatened Species lacks coverage on this topic, and 140 species are currently “missing in action,” having been previously reported in this great river but not found in this latest survey.

A project supported by the Toyota Motor Corporation and the SEE Foundation is currently underway to address this information gap by collating all available knowledge on these species, determine their risk of extinction, and help guide priority conservation action.

This June, the IUCN World Conservation Congress in Marseille, France, will bring together governments, civil society, indigenous peoples, and academia on an equal footing to agree on actions for change. Freshwater will be a key theme at the IUCN Congress, with IUCN Members voting on a number of motions aimed at protecting rivers and wetlands.

We will never see the extraordinary Yangtze Paddlefish again — it is gone forever. Now it is up to the global community to ensure this tragedy is never repeated.

A specimen of a mature Chinese Paddlefish (Psephurus gladius) exhibited in the Museum of Hydrobiological Sciences, Wuhan Institute of Hydrobiology, Chinese Academy of Sciences. Photo licensed under CC BY-SA 4.0.

CITATIONS

• Zarfl, C., Berlekamp, J., He, F., Jähnig, S. C., Darwall, W., & Tockner, K. (2019). Future large hydropower dams impact global freshwater megafauna. Scientific Reports, 9(1), 1-10. doi:10.1038/s41598-019-54980-8

• Zhang, H., Jaric, I., Roberts, D. L., He, Y., Du, H., Wu, J., … & Wei, Q. (2020). Extinction of one of the world’s largest freshwater fishes: Lessons for conserving the endangered Yangtze fauna. Science of the Total Environment, 710(136242). doi:10.1016/j.scitotenv.2019.136242

William Darwall is head of the Freshwater Biodiversity Unit, IUCN Global Species Programme.