More than 7 million tails were released for more than 30 years without monitoring of natural spawning for 4 consecutive years
Can artificial release save Chinese sturgeon?
Produced by Deep Eye Studio
For the fourth consecutive year, scientific research institutions have still not monitored the natural spawning of Chinese sturgeon.
Without eggs, it is impossible to breed new life.
Wei Qiwei, a researcher at the Yangtze River Fisheries Research Institute of the Chinese Academy of Fishery Sciences and a member of the Sturgeon Expert Group of the World Conservation Union Species Survival Committee, confirmed the bad news in an interview with a reporter from Science and Technology Daily.
The interruption of natural reproduction has become the biggest dilemma facing the ancient species of Chinese sturgeon.
"The situation is not optimistic." He sighed, "It is possible that the Chinese sturgeon just left."
"The natural population has declined severely, and the living conditions are very endangered." "The ancient sturgeon seems to be involved in the extinction vortex." "The wild population of Chinese sturgeon has reached the brink of extinction"... Looking at the papers published in recent years, you will find that Authors from different scientific research institutes, when describing the status quo of Chinese sturgeon, all bring some sighs and sorrows.
Fortunately, the window of protection has not yet closed.
In mid-April this year, the second-generation Chinese sturgeon with 10,000 tails was released to the Yangtze River from the Rouge Garden in Binjiang Park, Yichang, Hubei.
This is the 64th artificial release of Chinese sturgeon by China Three Gorges Corporation (hereinafter referred to as the Three Gorges Group) in more than 30 years.
The artificially bred descendants of Chinese sturgeon bear unspoken expectations from mankind-expecting that they can supplement the wild population of Chinese sturgeon and bring new hope to Chinese sturgeon.
Natural reproduction interrupted, danger signal
The fall monitoring of 2020 has returned without success.
In fact, from 2017 to 2020, for many years in a row, that mung bean-sized egg never appeared again.
The Chinese sturgeon was listed as a national first-class protected animal in 1989 and is currently critically endangered.
This is a kind of Haihe migratory fish with a huge body.
After living in the Yangtze River for hundreds of millions of years, they formed a set of spawning and reproduction mechanisms adapted to the Yangtze River environment.
The Chinese sturgeon was born in the upper reaches of the Yangtze River and spends most of its life in the ocean.
But when the signal of reproduction starts, they will find the Yangtze River estuary exactly as if they were being guided by something, and then travel upstream for 3,000 kilometers, return to their birthplace, and arrive at the Jinsha River (Yibin-Pingshan) on the upper reaches of the Yangtze River. The river section spawns and reproduces.
Later, the Gezhouba Water Control Project blocked the migration and reproduction channels of Chinese sturgeon.
To protect Chinese sturgeon, the Chinese Sturgeon Research Institute was established with the approval of the Ministry of Water Resources in 1982.
It is my country's first rare fish scientific research institution established by the construction of a large-scale water conservancy project.
Dr. Jiang Wei from the Chinese Sturgeon Research Institute told reporters that the Chinese sturgeon is a flagship species, and it has a strong indicating significance.
The resource level of its population and the state of the wild population are a systematic manifestation of the health status of the Yangtze River and the ocean basins.
"If you want to choose a species that can represent the Yangtze River ecosystem, it is the Chinese sturgeon."
It is difficult to protect a big fish; it is even more difficult to protect a big fish with such a complicated life history.
Jiang Wei said that when he did the protection of Chinese sturgeon, he was ready to fight a protracted battle. This is definitely not an overnight effort.
Nowadays, every autumn, many scientific research institutes will carry out monitoring surveys on Chinese sturgeon spawning grounds under Gezhouba.
Chinese sturgeon is a rare fish that breeds in autumn.
Chinese sturgeon eggs, black, the size of mung beans, very sticky.
They will "hide" on the surface of gravel or in crevices, which may be a strategy chosen by Chinese sturgeon parents to avoid predators for their children.
Wei Qiwei told reporters that there are four main monitoring methods: hydroacoustic detection, which is used to detect the number of Chinese sturgeon parents in the survey area; egg collection on the river bottom, and direct observation of samples collected by the river bottom network; underwater video observation, by ship Equipped with a high-definition camera to patrol the bottom of the river; there is also a traditional way-anatomy of egg-eating fish.
The fall monitoring of 2020 has returned without success.
In fact, from 2017 to 2020, for many years in a row, that mung bean-sized egg never appeared again.
This is indeed a dangerous signal.
It is difficult to know the exact number of Chinese sturgeons.
Researchers generally infer the status of the population by monitoring the river section of the spawning ground.
Wei Qiwei told reporters this set of statistics: In the 1970s, the number of breeding populations of Chinese sturgeon migrating to the Yangtze River each year reached more than 2,000.
Soon after the closure of Gezhouba in the 1980s, the number of broodstock broodstock of Chinese sturgeon that reached the spawning ground under Gezhouba continued to decline every year: from 2009 to 2012, it dropped to more than 100, and after 2013 it further dropped to less than 100, 2017-2019 The number of migratory groups is only about 20.
If you draw a graph, you will see a curve that drops sharply over time.
Wei Qiwei analyzed the reasons for the decline of the Chinese sturgeon population to this point: the construction of the Gezhouba blocked the migration channel of the Chinese sturgeon, and they lost the spawning ground that was once distributed in the upper reaches of the Gezhouba.
The temperature stagnation effect formed by the water storage operation of many hydropower projects on the Yangtze River has increased the water temperature during the breeding season of Chinese sturgeons, further reducing their natural reproduction time window.
Coupled with multiple factors such as fishing, shipping and pollution, the living environment of Chinese sturgeon has deteriorated drastically.
Full artificial propagation technology has been broken, artificial propagation and release are controversial
The ultimate goal of artificial breeding of Chinese sturgeons is to return them to the Yangtze River so that they can replenish the wild population.
Over the past 30 years, more than 7 million Chinese sturgeon have been released, but the proliferation of Chinese sturgeon resources has "little effect."
Wei Qiwei's team published a paper on the extinction of the white sturgeon in early 2020.
It is a sturgeon living in the Yangtze River with a larger body but a lower public awareness.
According to their calculations, the white sturgeon was extinct from 2005 to 2010, but humans did not realize it at that time.
The fate of the white sturgeon reminds people that once the key time point for protection is missed, it is really too late.
Fortunately, unlike the white sturgeon, the Chinese sturgeon still retains an artificially bred population.
The Chinese Sturgeon Research Institute, located in Yichang, Hubei, is now part of the Three Gorges Group and is the only institution that continues to reproduce and release Chinese sturgeons.
Founded nearly 40 years ago, the Chinese Sturgeon Research Institute has made a series of progress in artificial breeding of Chinese sturgeon.
The breakthrough of full artificial reproduction in 2009 is a milestone progress.
It means that to breed Chinese sturgeon, it is no longer necessary to fish wild broodstock from the wild.
The offspring of the wild broodstock are the offspring of the Chinese sturgeon; the offspring of the Chinese sturgeon that grew up in a fully artificial environment are the offspring of the second generation of the Chinese sturgeon, and they are now the main targets of the Three Gorges Group.
The Chinese Sturgeon Research Institute also reserves parthenosexual reproduction techniques for extreme situations.
Today, the sex ratio of wild Chinese sturgeon populations has been out of balance.
If one day in the future, only female individuals are left, even if it can no longer find a male partner, people can still artificially induce and activate Chinese sturgeon eggs to produce offspring.
Researchers have made a series of technical preparations.
If everything is irreversible, at least future generations will still be able to see Chinese sturgeon.
But the ultimate goal of artificial breeding of Chinese sturgeons is to return them to the Yangtze River and allow them to replenish wild populations.
According to statistics, many institutions, including the Chinese Sturgeon Research Institute, have released more than 7 million Chinese sturgeons in the past 30 years.
Some experts concerned about the ecology of the Yangtze River sighed to the reporter: "More than 7 million tails, so many have been released, but what's the effect?"
Huang Zhenzhen, a professor at the China Institute of Water Resources and Hydropower Research, also bluntly stated in the paper that the proliferation of Chinese sturgeon resources "has little effect."
Questions have always been there: Is it really useful to release it?
Where did the released Chinese sturgeon go?
Since 2014, the Chinese Sturgeon Research Institute has carried out the tracking of Chinese sturgeon release marks.
Monitoring data in 2019 show that 73% of the released Chinese sturgeon can reach the sea after release.
Jiang Wei observed that many freshwater fish will swim to the upper reaches of the Yangtze River after being released.
But the destination of Chinese sturgeon is very clear-to the downstream, to the ocean.
This also means that artificial breeding did not obliterate the instinct of Chinese sturgeon.
It takes 10 or even 15 years for Chinese sturgeon to become sexually mature.
So, did they follow their instincts and return to the Yangtze River to lay eggs?
This is really hard to tell.
Jiang Wei said that after 2009, scientific research and fishing of wild Chinese sturgeon has been banned.
If it takes too long, some short-term marks on the Chinese sturgeon will be lost; marks that can be maintained for a long time can only be confirmed after salvage.
"To the extent permitted by our capabilities and facilities, we have done a lot of basic protection work. Maybe everyone has a different perspective on analyzing problems. But the two general directions of fish protection are'in-situ conservation' and'ex-situ conservation'. Protection', we have been advancing this work in accordance with the thinking and framework of the protection of wild aquatic life." Jiang Wei said.
In situ conservation, as the name suggests, refers to the protection of habitats and spawning grounds.
One of the important measures in ex situ conservation is artificial seed conservation and artificial breeding.
"The effect of possible advancement is not so obvious to others, and there are indeed problems that need to be solved urgently." Jiang Wei said frankly, "but we have to go on and take action. While doing it, we will see what we can improve. ." Not afraid of controversy.
Scientific issues, while arguing, verifying, and searching.
The protection of Chinese sturgeon itself is a systematic project.
"The most important thing is that we must continue to form a joint force for research and protection, and work together for this matter."
Fortunately, under the overall strategy of "Protection of the Yangtze River", starting from 2020, the Yangtze River has entered a ten-year ban on fishing.
"After the fishing ban, we are still very confident about the survival rate of Chinese sturgeons after release." Jiang Wei emphasized.
The release must be more scientific, and the protection process must race against the speed of extinction.
The past releases were not useless, but not enough and not standardized enough.
A sound Chinese sturgeon reproduction and release and resource restoration plan should be formulated.
The ten-year ban on fishing is a rare window period.
Wei Qiwei knows that he must seize this opportunity.
The reporter asked him: "Nowadays Chinese sturgeon is facing many difficulties. Among so many measures to save fish, what do you want to talk about most?"
Wei Qiwei didn't hesitate much, and said bluntly: "It's better to release it." In his opinion, the past release was not useless, but not enough and not standardized enough.
Huang Zhenzhen also pointed out that in the past, insufficient attention was paid to the effects of release, insufficient research on improving the survival rate of juvenile release, and the serious lack of relevant basic research results, and release was blind.
Wei Qiwei conducted a detailed analysis of the release.
Over the past 30 years, more than 7 million Chinese sturgeons have been released.
However, from the 1980s to the early 1990s, small fishes that had not yet eaten were released.
These fish are too easy to die, in fact they are not suitable for manual release.
For more than 30 years, the truly "effective" release group is actually 1.3721 million juveniles and juveniles that have passed the peak of death.
Calculated in this way, the actual average annual discharge of Chinese sturgeon is less than 40,000, which is ten or even a hundred times worse than the number of similar discharge specifications in foreign countries.
An example that can be used for reference is that from 1961 to 1991 before the disintegration of the Soviet Union, the Soviet Union released the three main sturgeons (the offspring of Russian sturgeon, flash sturgeon, and European sturgeon) that were artificially reproduced in rivers such as the Volga River. They are all on the order of one million tails to ten million tails.
Later, they succeeded in restoring the natural reproduction of these fishes.
Wei Qiwei calculated that based on the current amount of Chinese sturgeon that needs to be replenished, the amount of Chinese sturgeon to be released a year should reach 3 million.
"That is a capital investment of more than ten million yuan."
How to get the funds and how to release it more scientifically are all difficult questions.
Wei Qiwei believes that a sound Chinese sturgeon breeding and release and resource restoration plan should be formulated, such as the resource sharing and breeding utilization plan for the existing conservation resources, the genetic management and scientific breeding matching plan based on the conservation population, and the artificial reproduction and release Chinese sturgeon's wild training program, scientific planning of breeding and release specifications, scale and location, and release effect monitoring and evaluation plan...Moreover, a breeding and release guarantee mechanism must be established to solve the funding requirements and operation management problems of Chinese sturgeon reproduction and release.
In fact, the former Ministry of Agriculture has issued the "Chinese Sturgeon Rescue Action Plan (2015-2030)".
However, Wei Qiwei said that many ideas have not yet been implemented.
"The Chinese sturgeon is already in a predicament. It needs people to really care and invest." Wei Qiwei tapped his fingers on the table and said almost eagerly, "The baiji is extinct, and the white sturgeon is also extinct. Can't wait, the Chinese Sturgeon Association They are old and will die, and in another ten years, they will be boiled to death."
If the wild population is really lost, the artificial population of Chinese sturgeon will also degenerate.
The process of protection must race against the speed of extinction and must act.
Action can give the Chinese sturgeon a turning point in its destiny.
The Chinese sturgeon can't speak, and uses the decreasing number as a signal for help.
Those who guard it must speak for it.
"I have studied the sturgeon for a lifetime. If there is no sturgeon, can I live a safe life? This fish must be preserved with me; if I preserve it, I will have a chance in the future!" Wei Qiwei emphasized that the Chinese sturgeon rescue plan is about to land. In particular, it is necessary to rescue and cultivate the existing generation of more than 3000 Chinese sturgeon, give full play to its reproductive efficiency, and implement large-scale reproduction and release.
"Only in this way can the natural population of Chinese sturgeon recover in 10-15 years!"
In addition, the implementation of comprehensive protection measures for Chinese sturgeon also includes offshore fishing control and habitat restoration, creating conditions for the protection and restoration of life in the Yangtze River and offshore waters.
Saving fish is a heavy responsibility and also a heavy emotion.
Speaking of emotions, this expert, who has always been dignified, finally had a smile on his face.
"It's not only that I have feelings for it, many people have feelings for it." Wei Wei's voice softened, "This fish, you can see it so you can forget to eat. You think other foreign sturgeons just don't have it. It's beautiful. It's beautiful and mighty."
The process of protection must race against the speed of extinction.
Action can give the Chinese sturgeon a turning point in its destiny.
The Chinese sturgeon can't speak, and uses the decreasing number as a signal for help.
Those who guard it must speak for it.
Written by: Our reporter Zhang Galun Planning: Liu Li