HR Excellence in Science
Date: 06.01.2020

Chinese Paddlefish confirmed as extinct

A new study by researchers from the China, Czech Republic and UK, concluded that the Chinese Paddlefish can now be confirmed as extinct. With its recorded length of up 7 m, the Chinese paddlefish (Psephurus gladius) was one of the largest freshwater fishes in the world. It was one of only two extant species of paddlefishes (the other being the American paddlefish), a relict lineage that have existed since the Lower Jurassic, 200 million years ago, and occupy a special place in fish evolution. The study was based on a large-scale survey throughout the Yangtze River basin during 2017 and 2018, and a statistical inference of extinction based on confirmed sightings of the species.

Chinese paddlefish historically lived in many large rivers that flow into the West Pacific, but since 1950s it was commonly seen only in the Yangtze River. Since the late 1970s it was rapidly declining due to overfishing and habitat fragmentation, especially after the construction of the first and lowermost dam (Gezhouba Dam) in the Yangtze in 1981. The dam separated the fish into two isolated populations and blocked the migration route, preventing adult fish from moving to the upper reaches of the river to spawn. It was listed as one of the top-level protected animals in China, and as Critically Endangered within the IUCN Red List. However, despite all the conservation attention and efforts, the population continued to decline, with occasional sightings until the last known record in 2003.

A new study, conducted through collaboration of researchers from the Yangtze River Fisheries Research Institute of the Chinese Academy of Fishery Sciences, Biology Centre of the Czech Academy of Sciences, and the Durrell Institute of Conservation and Ecology of the University of Kent, Here, concluded that the Chinese paddlefish can now be confirmed as extinct. The study was based on a large-scale survey throughout the Yangtze River basin during 2017 and 2018, and a statistical inference of extinction based on confirmed sightings of the species.

A basin-wide capture survey during 2017-2018 found 332 fish species, but did not find a single live specimen of Chinese paddlefish. Chinese paddlefish is also one of a very few fish species which has never been observed during all historic fish surveys in Yangtze, for more than 15 years.

Based on the last 210 sightings of Chinese paddlefish during the period 1981-2003, the statistical analysis of sighting records indicated that the species became extinct by 2005, and no later than by 2010. Analysis also showed that the paddlefish probably first became functionally extinct by 1993, by being rendered unable to reproduce. It is likely that the lack of reproduction, due to habitat fragmentation, was among the major causes of extinction. As no live specimens exist in captivity, and no living tissues are conserved for potential resurrection, the fish should be considered extinct according to the IUCN Red List criteria. Loss of such unique and charismatic megafauna representative of freshwater ecosystems is a reprehensible and an irreparable loss.

There are multiple lessons to be learned from the extinction of Chinese paddlefish, especially that it is critical to prioritize conservation efforts on those species with the greatest extinction risk in the Yangtze River. For example, the long spiky-head carp and Sichuan shoveljaw fish have not been observed for many years. In addition, some species that are confirmed to be present are known to be rapidly declining with no natural reproduction observed for years, such as Chinese sturgeon, Yangtze sturgeon, Chinese sucker, Sichuan taimen and largemouth bronze gudgeon. While for some species the window of conservation opportunity may have already closed, for those that still persist it is important to seize what opportunity remains. Ongoing conservation measures, such as establishment of aquatic protected areas, stock enhancements, implementing action plans for key species, habitat restoration, and law improvement and enforcement, will have to be greatly intensified in the future and specifically designed for target species. Sustainable development and biodiversity conservation will have to be widely recognized as priorities for the whole Yangtze River basen, to prevent and mitigate ongoing irreversible changes in the region.

The sad news and the extinction report received considerable level of public attention and coverage in major new outlets and in social media. For example, according to an article published in The Global Times, the topic 'extinction of the Chinese paddlefish' had been viewed more than 490 million times on Sina Weibo, Chinese microblogging platform, within less than 2 weeks following the paper publication. The same article also concludes that the news about the extinction seems to have been a wake up call for the public to join the campaign to protect endangered species in the Yangtze basin. 

 

For more detailed information check the article, published in Science of the Total Environment:

Zhang H, Jaric I., Roberts DL, He Y, Du H, Wu J, Wang C & 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, 13642. doi:10.1016/j.scitotenv.2019.136242

https://www.sciencedirect.com/science/article/pii/S0048969719362382

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