Source: Global Times
The International Union for Conservation of Nature (IUCN) recently released an updated report on the Red List of Global Endangered Species, announcing the extinction of the white sturgeon that lives in China's Yangtze River and has survived for about 150 million years. Nearly 20 years ago, Wei Qiwei, the only member of the IUCN Sturgeon Expert Group in China and chief scientist of the Yangtze River Fisheries Research Institute of the Chinese Academy of Fishery Sciences, discovered a wounded white sturgeon, which was the last time humans saw this wild animal that was once "in the same frame" as the dinosaur. In an interview with the Global Times reporter on the 25th, Wei Qiwei said that the extinction of the white sturgeon warns people that more efforts must be made to protect the Yangtze River sturgeon, Chinese sturgeon and other fish.
According to the definition given by the IUCN website, when the last individual of a species dies, the species is considered extinct. Specifically, a species is considered extinct when an exhaustive survey of a species' historically known or predicted habitat is carried out at an appropriate time and fails to record any individual. In December 2019, Wei Qiwei published an article in an international academic journal saying that between 2005 and 2010, the white sturgeon has become extinct, not only that, but in 1993, the species has been functionally extinct.
"Due to the limited data on the study of white sturgeon, there is no record of lifespan. According to our estimates, the lifespan of white sturgeon is about thirty or forty years," Wei Qiwei told the Global Times reporter, in a paper published in 2019, he and his colleagues believe that the last breeding of white sturgeon may be around 1990, and the white sturgeon that was born is likely to have reached the end of its life.
In January 2003, Wei Qiwei found an injured white sturgeon in the Nanxi section of the Yangtze River in Yibin, which was also the last time people saw the figure of the white sturgeon. According to Wei Qiwei, the last white sturgeon found had a life expectancy of about 20 years at that time, and it is likely to die now. "So far we have not found any other living white sturgeon, so we have decided that this species is extinct."
The white sturgeon is an endemic species of the Yangtze River and one of the very few ancient fish species that survived from the Cretaceous Period 150 million years ago, and is a national first-class protected wild animal. Adult white sturgeon are 7 meters long and weigh up to 500 kg. Wei Qiwei told the Global Times reporter that the white sturgeon is larger, eats fish for a living, and is a top meat eater in the Yangtze River ecosystem. From an evolutionary point of view, the white sturgeon belongs to the sturgeon order Spoon sturgeon family, and its ancestors are earlier than other fish. Therefore, the study of white sturgeon has more important significance.
But unfortunately, the white sturgeon that survived the drastic changes in the earth's environment now only exists in the museum's specimen exhibition, and researchers have not found a single surviving white sturgeon. In the past few decades, people have not tried to farm white sturgeon, wei Qiwei rescued a white sturgeon in 2002, but it is still dead after 29 days of survival. Wei Qiwei told the Global Times reporter that it was a pity that the artificial breeding of white sturgeon could not be realized, and the conditions were limited at that time, and no one could raise white sturgeon alive.
Scholars, including Wei Qiwei, believe that the main reason for the extinction of the white sturgeon is that human activities have caused changes in their living environment, such as overfishing that has led to a reduction in food for the white sturgeon. In addition, the construction of some water conservancy facilities has also affected the migration of white sturgeon to the upper reaches of the Yangtze River to spawn.
The news of the extinction of the white sturgeon has increased public concern about the ecological protection and species diversity of the Yangtze River, and many people on social media are concerned about the situation of the Chinese sturgeon and the Yangtze River sturgeon. In the latest report released by the IUCN, the Yangtze River sturgeon has been identified as extinct in the wild.
In addition to the Yangtze River white sturgeon, according to the latest report from IUCN, 26 species of sturgeon are threatened with extinction. The IUCN's reassessment of global sturgeon shows that 100% of the world's remaining 26 sturgeon species are at risk of extinction, up from 85% in 2009; About two-thirds of sturgeon stocks are critically endangered. Globally, major threats to sturgeon include illegal fishing from the illegal trade in wild caviar and fish meat, dams blocking their migration routes, sand and gravel mining destroying their spawning grounds, and habitat loss. Aina Luvi, chair of the IUCN Sturgeon Expert Group, said, "The results are shocking and sad, but expected." The assessment shows that sturgeon are still unable to shed the title of 'the world's most threatened taxa'. ”
Wei Qiwei told the Global Times reporter that great efforts must be made to protect the Yangtze River sturgeon and the Chinese sturgeon. At present, the Chinese sturgeon has been artificially bred and cultivated, and it has two generations of children. Public reports show that the Yangtze River has been carrying out the release of Chinese sturgeon and Yangtze River sturgeon in recent years. Statistics show that as of now, the mainland has cumulatively released about 7 million Chinese sturgeon, and the Yangtze River sturgeon has also been released in large quantities. However, the effect of artificial stocking on natural population recovery is still not obvious, and the relevant institutions have not monitored the spawning of Chinese sturgeon in the Yangtze River for five consecutive years, and the Yangtze River sturgeon has also been assessed as wild extinction by the IUCN due to the failure to find juvenile fish that have increased and stocked stocks.
There are more than 4,300 kinds of aquatic organisms distributed in the Yangtze River Basin, including more than 400 kinds of fish and more than 170 kinds of fish endemic to the Yangtze River; It has 12 species of aquatic organisms under national key protection, such as white sturgeon, white sturgeon, Chinese sturgeon, Yangtze River sturgeon and Yangtze River finless porpoise. In recent years, China has increased the protection of aquatic organisms in the Yangtze River Basin, and the Yangtze River has begun to implement a "ten-year ban on fishing". In addition, the Ministry of Agriculture and Rural Affairs has also successively issued the "Chinese Sturgeon Rescue Action Plan (2015-2030)", "Yangtze River Finless Porpoise Rescue Action Plan (2016-2025)" and "Yangtze River Sturgeon (Dashi Sturgeon) Rescue Action Plan (2018-2035)".
Wang Yamin, a professor at the School of Oceanography at Shandong University's Weihai Campus, told the Global Times that the extinction of the white sturgeon reflects various problems in the ecological environment of the Yangtze River. The protection of the Yangtze River has been strengthened through various measures in China, but some species have been difficult to recover.
The "Blue Book on the Protection of Aquatic Wild Animals in China" released by the Aquatic Wildlife Conservation Branch of the China Wildlife Conservation Association this year also mentioned that the mainland has successively carried out the protection of Chinese sturgeon through legislative protection of species and their key habitats, long-term large-scale artificial breeding and stocking, artificial group conservation and a large number of scientific research, etc., and achieved certain results. However, it still faces serious problems, such as damming, waterway construction and the impact of human activities such as shipping, water pollution and urbanization.
Researchers including Wei Qiwei are also working hard to preserve the "tinder" of these rare fish through scientific and technological means, he told the Global Times reporter that the team he led developed a fish germ cell transplantation technology, which can extract germ cells from male or female sturgeon, transplant them into another fish, and form sturgeon sperm and eggs in the latter's body, and then complete reproduction through in vitro fertilization.
"However, white sturgeon currently have only specimens, no living cells, and cannot take advantage of this technology, and we hope that such technology can help other populations recover." Wei Qiwei said.