Jimu news reporter Chen Lingmo Zhao Bei
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On November 9, the early winter sun faded from time to time, and the color of the moji mountains was suitable for the color of the moji, reflecting the water birds and boats on the river.
Research station under Moji Mountain
"The water temperature is 21 degrees Celsius, which is suitable for detection today." At about 9:00 a.m., with the departure of the "Zhongyuke 505" scientific research vessel, the scientific expedition survey of the spawning grounds of the Chinese sturgeon on the Yangtze River in 2021 was officially launched at the Yichang Fishery Administration Wharf. In the next three months, four scientific research institutions, including the Yangtze River Fisheries Research Institute of the Chinese Academy of Fishery Sciences, the Institute of Hydrobiology of the Chinese Academy of Sciences, the Institute of Water Engineering Ecology of the Chinese Academy of Sciences of the Ministry of Water Resources, and the China Three Gorges Corporation of China, will continue to look for the "black pearl" they have in mind - Chinese sturgeon eggs at the bottom of the river.
In January this year, the key waters of the Yangtze River Basin fully implemented the "ten-year fishing ban". Yangtze River finless porpoises appear frequently in urban areas, rare fish such as knife fish that have not been seen for many years have returned, and wintering migratory birds in lakes and wetlands have increased year by year... The conservation of biodiversity in the Yangtze River has achieved remarkable results, and the protection of the Yangtze River has curbed the trend of accelerated environmental deterioration to a certain extent.
However, there are still many rare flagship species of the Yangtze River in a worrying situation, and the Chinese sturgeon is one of the representatives. Since 2017, researchers have not monitored the natural reproduction of Chinese sturgeon in the Yangtze River for four consecutive years.
Four major monitoring methods to fight, just to find the "black pearl"
The lower reaches of Gezhouba in Yichang are the core nature reserves of Chinese sturgeon and the only natural breeding and spawning ground for Chinese sturgeon that has been confirmed so far.
"The suitable spawning water temperature for Chinese sturgeon is 21 degrees Celsius to 16 degrees Celsius." Yang Junlin, a member of the research group on the protection of endangered fish at the Yangtze River Fisheries Research Institute of the Chinese Academy of Fishery Sciences, said. At about 8:30 a.m. on November 9, Yang Junlin and her colleagues put a fish detector (sonar) into the water and fixed the upper end to the bow of the boat. If the equipment is operating properly, the fish finder will spend the entire winter with the Zhongyuke 505.
Professor Wei Qiwei directed the scientific expedition in Yichang
After leaving the port, the research vessel zigzag sailed along the "zigzag" line on the river, and in the morning it traveled to the Gezhou Dam and then down the river for exploration, with a full-day voyage of about 25 kilometers.
Yang Junlin introduced that the main section of the river in this inspection is from Gezhou Dam to Lujia river shoal, about 80 kilometers.
During the voyage, large ships pass by from time to time next to the research vessels.
The expedition officers put the fish probe into the river
Yang Junlin said that the fish detector is mainly to explore the distribution area and density of Chinese sturgeon, "to find out where there are Chinese sturgeon, how many Chinese sturgeon, and then provide guidance for the next step of spawning field investigation." For example, under the Gezhou Dam, on the morning of the 9th, two suspected Chinese sturgeon broodstock signals were detected, which is the suitable water for Chinese sturgeon to spawn, there are many pebbles under the water, and Chinese sturgeon usually lay eggs on pebbles. ”
There are four main methods of investigation and monitoring of Chinese sturgeon spawning grounds: egg-eating fish dissection, river bottom egg collection, underwater video, and sonar monitoring.
Expeditions dissect the egg-eating fish
According to the scientific expedition plan, in the next step, the research group will collect some Chinese sturgeon eggs and egg-eating fish that specialize in eating Chinese sturgeon eggs in relevant waters according to the data obtained by the fish detector. Egg-eating fish are mainly fish that inhabit the bottom of the Yangtze River, and will follow the Chinese sturgeon and swallow the eggs during the spawning period of the Chinese sturgeon. Through the data obtained from the dissection of the egg-eating fish, it is possible to determine whether the Chinese sturgeon has "natural reproduction", and then the number of Chinese sturgeon in the breeding group can be deduced.
The natural breeding of Chinese sturgeon has not been monitored in the Yangtze River for four consecutive years
"The situation is already grim." As the head of the scientific expedition team, Wei Qiwei, a researcher at the Yangtze River Fisheries Research Institute of the Chinese Academy of Fishery Sciences and the director of the Key Laboratory of Freshwater Biodiversity Conservation of the Ministry of Agriculture and Rural Affairs, insisted on staying at the Yichang scientific expedition site. He said that as a core protected area for Chinese sturgeon, Yichang has not found natural breeding of Chinese sturgeon for 4 consecutive years.
The Chinese Sturgeon Spawning Farm Survey began in 1981 and has been around for 40 years. Wei Qiwei is also here, and has been "dealing" with rare fish such as Chinese sturgeon for 37 years. In the 1990s, he also rescued an injured white sturgeon here and took a precious photograph of the white sturgeon, which became the only few remaining white sturgeon photos.
"A thousand pounds of wax." This is a saying that the fishermen of the Yangtze River have been passing down since ancient times. Wax is the Chinese sturgeon, and the elephant is the white sturgeon.
Unfortunately, Wei Qiwei and his comrades-in-arms did everything in their power to keep the footsteps of the "Yangtze River Fish King" white sturgeon far away. "At that time, the scientific research technology was not yet mature, and before we knew about the white sturgeon, it had left us." In 2003, the last white sturgeon disappeared from view. In January 2020, the white sturgeon was declared extinct. When Wei Qiwei, a member of the IUCN Committee on the Survival of Species Sturgeon Expert Group, made public the fact of the extinction of the white sturgeon through a paper, the world was shocked to realize that "the first smell is a farewell".
"I used to study white sturgeon, but there was no white sturgeon." Retaining the Chinese sturgeon has become the greatest mission of Wei Qiwei.
Registration of laboratory tests after dissection
In the 1980s, with the construction of Gezhouba, the Chinese sturgeon, which originally had to go up the river to spawn on the Jinsha River, could only stay in the waters under Gezhouba to breed offspring. Historically, the breeding grounds of the Chinese sturgeon were distributed in many places along the Yangtze River, and its river section was 600 kilometers long; now it is only within a range of 30 kilometers, and the known fixed spawning grounds are only within 4 kilometers above the mouth of the temple.
"Thirty or forty years ago, thousands of adult Chinese sturgeon migrated to the Yichang section of the Yangtze River every year to breed." Wei Qiwei stood at the bow of the scientific expedition ship, and his words revealed worry: "After 2003, the upstream dam stored water, destroying the natural water temperature change, and the broodstock gonad development and spawning of Chinese sturgeon are particularly sensitive to water temperature." In the past, the water temperature reached 21 degrees Celsius after October 1, and by November 9, the breeding period was basically over. Now, breeding has not yet begun on November 9, and the breeding period has been postponed to after early November. ”
These reasons have led to a sharp decline in the population of Chinese sturgeon. After 1981, the number of adult Chinese sturgeon monitored migrating here decreased by about half or even an order of magnitude every decade. In particular, in 2020, only 13 adult Chinese sturgeon were monitored and there was no natural breeding.
Wei Qiwei said that before 2013, although the natural breeding and spawning of Chinese sturgeon decreased, it was monitored every year. In 2013, for the first time, the natural spawning of Chinese sturgeon was not monitored. In 2014, the breeding of Chinese sturgeon was not monitored in Yichang, but in the spring of 2015, the juvenile Chinese sturgeon was monitored at the mouth of the Yangtze River in Shanghai, which shows that the Chinese sturgeon had natural breeding activities in the Yangtze River in 2014, but people did not know where the breeding site was (later through microchemistry and molecular biology, it was found that the natural breeding activity in that year should still be above the Mouth of the Yangtze River, and may not be the spawning ground under Gezhouba). In 2015, no natural breeding was found, and in the winter expedition of 2016, the natural reproduction of Chinese sturgeon was finally monitored in Yichang. But the good news didn't last long. Beginning in 2017, natural reproduction has not been monitored for four consecutive years.
Expert suggestion: establish a scientific "seed preservation" plan for Chinese sturgeon
"In just a few decades, species such as white sturgeon, white sturgeon, anchovies, and anchovies that have survived in the Yangtze River for thousands of years have disappeared." Wei Qiwei said: "The most important thing at present is to find out the reasons for the extinction of species and find ways to keep the remaining endangered species." ”
At present, the effect of the "ten-year ban on fishing" on the Yangtze River has emerged, and many long-lost fish have returned. For example, the knife fish, one of the "Three Fresh Foods of the Yangtze River", the population is slowly rising. In June this year, researchers surveyed and monitored a knife fish in the Jiayu section of the Yangtze River, which was the second time in 30 years that the knife fish was traced back to the northern section of the Yangtze River.
"A ten-year ban on fishing is enough for most Yangtze River fish because they are sexually mature in three or four years. However, the sexual maturity of Chinese sturgeon generally takes 18 years, and in rare cases, it takes 14 years. Wei Qiwei said that in 2020, only a dozen adult Chinese sturgeon were found in the Yichang River section, which did not reach the density of natural breeding. He believes that the number of wild Chinese sturgeon that can return to the sexual maturity under GezhouBa reaches 100, which may be the threshold of the number of naturally bred populations that can be continued, "There are more than 100 tails, males and females have the opportunity to meet for mating and insemination, and more than a dozen tails cannot find a suitable 'object', cannot reproduce naturally, and the natural population of Chinese sturgeon will eventually disappear." ”
In situ conservation, ex situ protection, and breeding and stocking are the main means of protecting rare flagship species in the Yangtze River, including Chinese sturgeon. For decades, relevant departments, scientific research units and enterprises have continued to exert efforts, and in 2015, the Ministry of Agriculture and Rural Affairs issued the "Chinese Sturgeon Rescue Action Plan (2015-2030)". The artificial breeding of Chinese sturgeon has achieved remarkable results, but the investment in artificial seed preservation sites, artificial and capital is large, and it is difficult to protect seeds. According to experts, there are about 3,000 Chinese sturgeon generations aged 13 and above in the country, with a serious small physique and a low proportion of maturity, and the deformity rate increases after the second generation of children, which requires continuous replenishment of wild resources.
In addition, the scale of breeding and stocking is not effective enough to meet the needs. Since the realization of the natural breeding of Chinese sturgeon under Gezhouba in 1983, about 7 million have been released into the Yangtze River, of which more than 50% are newly hatched Chinese sturgeon seedlings, and the proliferation effect is limited. Wei Qiwei said that the number of Chinese sturgeon that meets the requirements should be released in a year should reach 3 million, which requires more than 10 million yuan of capital investment. He suggested that scientific norms and implementation plans for the breeding and stocking of Chinese sturgeon and resource restoration should be formulated. In view of the resource sharing and breeding plan of existing seed preservation resources, it is also necessary to establish a guarantee mechanism to solve the problems of funding needs and operation management in the release.
Chang Jianbo, director of the Institute of Water Ecology of the School of Water Resources and Hydropower of Wuhan University, suggested that the Yangtze River Laboratory be set up to further integrate scientific research resources and provide strong scientific support for species protection. He suggested establishing a scientific "seed preservation" plan to rebuild their wild populations in due course. Scientific research has shown that species such as Chinese sturgeon are sensitive to sound and light, and the only Chinese sturgeon spawning ground is too close to the urban area, on the one hand, it is necessary to try to control sound and light pollution, on the other hand, measures can be taken to open up new spawning grounds for Chinese sturgeon.
On October 28 this year, the "Jingzhou Chinese Sturgeon Protection Base of the Ministry of Agriculture and Rural Affairs" was listed in the Jingzhou Zhonghua Sturgeon Protection Center. The Jiang Office of the Ministry of Agriculture and Rural Affairs strives to build six bases in Jingzhou in Three years, including high-standard Chinese sturgeon domestication and breeding, wild domestication, breeding and stocking, scientific research, science education, and foreign exchanges.
For this winter's spawning field expedition, although Wei Qiwei has worries, he will never give up looking for it. "Downstream of Gezhouba, the spawning grounds of the Chinese sturgeon, there is currently a group of finless porpoises living, which has become a business card of Yichang. We hope that the Chinese sturgeon can also become the city's business card, and the endangered situation of the Chinese sturgeon is more severe, and we hope to strengthen the attention and publicity of the protection of the Chinese sturgeon. ”
To this day, Wei Qiwei still misses the last white sturgeon that disappeared from view in 2003. He hopes that in the hands of himself and his colleagues, the Chinese sturgeon will be retained.
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