In 2020, our first move on wildlife, gave the Yangtze River white dragonfly. At the end of last year, the chief scientist of the Yangtze River Fisheries Research Institute of the China Academy of Aquatic Sciences published an English-language paper, “The Extinction of One of the World’s Largest Freshwater Fish: Lessons and Revelations of the Yangtze River’s Biological Protection”, published online in the international academic journal General Environmental Science. The paper points out that the white slugs were extinct between 2005 and 2010.
The white-haired specimen of the Museum of Aquatic Biology of the Chinese Academy of Sciences, Zhang Xinghai
For a time, there has been no sense of existence of the white dragonfly has received a lot of attention, “white slug extinction” topic in the hot search hung for a day. However, many media in the drawing, or mistakenly assigned to the Yangtze River white dragonfly’s next-of-kin kiss. After all, we don’t know too much about the white dragonfly, and the white dragonfly leaves too few images.
When a species is found to be extinct, in addition to mourning and remembrance, it is even more necessary to reflect.
The extinction of the white slug was determined by the model calculation
The white herring is a unique freshwater fish in the Yangtze River basin and is also the largest freshwater fish in the world, with a maximum body length of 7 meters. It had a long, sharp kiss, and was called “like a nose fish” by the ancients.
It’s very old. The spine of the white slug is primitive and most of the bones are cartilage. Fossil studies have shown that the earliest fossils of the white fern species were found in the late Jurassic period.
The spawning grounds of the white slugs are distributed in the lower reaches of the Jinsha River and the Yangtze River main stream above Chongqing, and mature individuals have the habit of swimming up before the breeding season.
“In fact, the number of white slugs has decreased significantly since the 1990s. Wang Chengyou, an associate researcher at the Yangtze River Fisheries Research Institute of the China Academy of Aquatic Sciences, previously told Science and Technology Daily. As early as 1996, the International Union for Conservation of Nature (IUCN) issued a red list of endangered species, the protection level of the white slug is listed as “extremely dangerous.”
In order to find traces of the white slug, the dangerous research team conducted a whole basin fishing survey in the Yangtze River basin. In 2017, they conducted web-format samples of the river basin, which were conducted quarterly for one to two months at a time. In 2018, the team conducted investigations mainly at and near 65 monitoring sites in and around the Yangtze River.
In addition, the team collected all the eyewitness reports on the white slugs, including papers, books, reports, news reports, and other unpublished data on white slugs retained by scientific institutions in recent decades. Combining this information, the team calculated that the white slugs should have been extinct between 2005 and 2010.
A population, without natural reproduction, has passed its normal life span, during which no individual sits, i.e. species can be identified as extinct, he said.
The last time I saw a white seedling, it was back in the early 1990s. For 30 years, no natural reproduction has been found in the white stork. The exact life span of the white slug is not known, but it is estimated that its natural survival time should be about 30 years. In 2003, the signal of the last wild white slug disappeared into the tracker, and there were no farmed individuals.
The conclusion of the extinction of the white stork is scientific and will not change, he said.
White slug protection level has not been adjusted
However, the news of the white slug’s extinction has not been announced.
On January 3rd, the IUCN said on its official microblog that the final results of the ongoing comprehensive assessment of the Asia-Europe fish had not yet been released and that it was expected to update the Red List of Threatened Species during the World Conservation Congress in June this year, formally release the results of the assessment and make appropriate level adjustments.
At present, the level of white slugs in the IUCN Red List is still “extremely dangerous”.
Beginning in the 1960s, IUCN compiled a worldwide red-skinned list of endangered species based on the information gathered and based on the report of the IUCN Survival Committee. In the IUCN standard, the global endangered species are classified from low to high in the endangered category as non-hazardous, low-risk, dangerous, endangered, critically endangered, wild extinction and extinction. In addition, there are “unassessed” and “data deficiency” ratings.
By definition, if there is reason to suspect that the last individual of a classification unit has died, it is considered extinct. If it is known that a classification unit lives only under cultivated or captive conditions, or only as a naturalized population living in habitats far from its past, it is considered to be a wild extinction. Extremely dangerous, the risk of extinction of a classification unit’s wild population is very high.
The endangered rating of species is important for species conservation. Jiang Zhigang, a researcher at the Institute of Zoology of the Chinese Academy of Sciences, pointed out in his paper that due to limited resources, when implementing endangered species protection projects, there must be specific protection measures for the endangered species, to determine the amount of resources invested in conservation, and to establish nature reserves and endangered species breeding centers according to the degree of endangered species. Local and relocation protection situ protection of such species.
It is understood that the evaluation of the endangered status of species is generally set up by the competent authorities (or organizations) to conduct a scientific review of the application reports of the endangered status of each species. The evaluation results are finally adopted and published by the supervisor (department) before the endangered status of the species can be finalized.
China also has a regularly issued “China Biodiversity Red List”, which is assessed from the living state of the organism itself. Assessment reports were issued for higher plants, vertebrates and large fungi in 2013, 2015 and 2018, respectively.
The assessment results at that time showed that the number of porpoises in the Yangtze River decreased sharply, from endangered to critical, and mackerel from endangered to critical danger due to overfishing.
There are a lot of fish on the brink of extinction.
The main reason for the extinction of the white herring was the inability to reproduce, and the water conservancy project cut off its migratory passages.
Overfishing, high-density shipping, habitat loss and fragmentation… Together, these factors push the white dragonfly to the brink.
All the substantive conservation work on the white slug satouts was initiated after 2006, but according to research by the team, it may have been as early as 2005, when the Yangtze River white slugs became extinct.
Missing the key time node is always missing.
In fact, the artificial breeding technology of the white slug has been in reserve. Previously, the Yangtze River white slug has not been a successful case of artificial breeding, and in recent years, after the technical conditions, the research team has never captured the living Yangtze River white slug.
Wang Chengyou introduced that there are two mainstream methods of artificial breeding, one for female nuclear development, one for “baby by belly”, that is, fish reproductive cell transplantation. Female nuclear development refers to the fish breeding method that stimulates the fish’s egg with the sperm of the nuclear inactivated fish and induces the nucleus to develop into an individual. The next of kin of the white dragonfly is the spoon kiss, and the spoon kiss has been artificially bred. If there is an adult female white slug, it can stimulate her eggs with an inactivated spoon-kissed sperm and perform artificial oxytocin. The second method is to transplant the reproductive cells of one fish into another, allowing the male and female of the other to produce the sperm and eggs of the former, allowing it to produce “offspring” with all the genetic information of the white herring.
However, there is no living white dragonfly, all the technical reserves empty.
The lesson is profound.
The paper points out that a comprehensive investigation of the Yangtze River basin should be conducted on a regular periodic basis. In the 2017-2018 survey, 140 species of fish were not collected. But due to a lack of data, the team was unable to determine the fate of the fish. It can also be seen from the tragedy of the white herring that changes in fish stocks are lagging behind in their response to the human threat and conservation action must be taken as soon as possible. In fact, many fish in the Yangtze River are already on the brink of extinction, and assessing their risk of extinction is critical and should be carried out as soon as possible. For some species, the time window to protect it may have closed. After all, extinction is only a matter of time when the breeding of wild populations of species does not sustain the minimum population of their existence. Priority must be given to the protection of fish stocks, such as slugs and Chinese slugs, that have not been discovered for many years, that have not been naturally bred for many years, or that their populations have declined significantly.
Depending on the biological and ecological characteristics of different populations, and the corresponding conservation measures are taken, this is a race against the rate of extinction of species.
From 2020, key waters of the Yangtze River will be classified into a 10-year fishing ban in stages.
The song of the white dragonfly has sounded, but the fate of other equally rare wild aquatic life in the Yangtze River is still in the hands of man.