Picture: Chinese sturgeon released on the Yangtze River Source/Oriental IC (same below)
At the beginning of this year, the "extinction of the Yangtze River white sturgeon" attracted attention. Wei Qiwei, chief scientist of the Yangtze River Fisheries Research Institute of the Chinese Academy of Fishery Sciences, published a paper, according to the model calculation, the Yangtze River sturgeon, a rare species endemic to the Yangtze River in China, is expected to be extinct from 2005 to 2010. Everyone sighed: "We have never met, and we have heard that it is a farewell." ”
Heartache, but much more than that. Over the years, the white mackerel and The Yangtze River anchovy have been declared functionally extinct by researchers, which is also heart-wrenching. Under the run of the guardians of the Yangtze River, the "Ten Years of Fishing Ban on the Yangtze River" policy has finally landed - from 00:00 on January 1 this year, the key waters of the Yangtze River Basin will be classified and phased to implement a fishing ban. As the fishing ban continues, good news continues to come: in August, the porpoise group known as the "giant panda in the water" reappeared in Wuhan. Recently, during the investigation of fishery resources and environment in the Yangtze River and the monitoring of the natural reproduction of Chinese sturgeon, relevant researchers found a guǎn in the Yichang section of the Yangtze River – this is the second time that researchers have discovered a helio in the Honghu River section in June 2017.
Picture: Helio infographic
Helios can't escape the fate of sharp reduction
Professor Tang Wenqiao, director of the Fish Research Office of Shanghai Ocean University, drew the appearance of hemorrhoids on white paper while recalling the experience of sampling in Poyang Lake more than 30 years ago. At that time, scientists could occasionally take pictures with the hemorring, "similar to grass carp, with a swollen belly."
Tang Wenqiao introduced that helio is a medium-sized economic fish that likes to inhabit the open waters of rivers and lakes. "The reproductive season is in May and June, when it enters the river and breeds up the river, laying drifting eggs." The first year of growth of the helio is fast, and then slow, it looks small, but it is also a "meat lover" who is "solid" - mainly feeds on invertebrates, such as aquatic insect larvae, but also eats small fish. "In the food chain, helios are in the upper middle. Fish that prey on small fish and shrimp must be smart and flexible themselves. ”
In the third season of "China on the Tip of the Tongue", there was a "steamed heli fish with shixian peach", although the raw material may be a grass carp by netizens, but it also reflects from the side that the heli fish, which was once one of the important economic fish in the Yangtze River Basin, has delicious meat. Once it is related to food, how can "foodies" be merciful? The growth cycle of helioli is relatively long, and the minimum age of sexual maturity is 3 years, generally 4 years. However, in order to satisfy the market, it is not uncommon for fry to be "brutally killed" - this sentence sounds familiar, but why is the experience of knifefish not?
From the "fall" of economic fish to the key protected wild animals in Hunan Province, helichryspers have now disappeared from many historical distribution points. In addition to overfishing, the reason for the sharp decline in its number can also be seen from its living habits. There must be flowing water for the breeding of heli fish, and with the construction of cement, the river and lake have become a 'broken road'. Coupled with high-intensity fishing, the "rations" of hemorrhoids are less, not to mention small fish and shrimp, and even snails are becoming less and less.
In Tang Wenqiao's view, if the helix disappears one day, it is difficult to say what impact it will have on the food chain, but the role of the heel in indicating the ecology of the Yangtze River Basin is still obvious.
The helios also have a "relative" named Anchovies. The snout of the anchovy is more pointed, is a large carnivorous and fierce economic fish, the longest can grow more than 50 kilograms, like to move in open waters such as rivers, lakes, reservoirs and so on. "Amaranth also has the habit of migrating in rivers and lakes, and in the past there were certain resources in the production area, but in recent years it is also difficult to find."
Picture: A map of the acacia
Yangtze River restoration "fish decides"
He Shunping, a researcher at the Institute of Hydrobiology of the Chinese Academy of Sciences, once said bitterly that in the Yangtze River Basin, many fish may be lining up to extinction. The collapse of the Yangtze River ecosystem is not appalling, but a fact that is happening, and the consequences are very serious.
In fact, we are not unaware of this problem: from the establishment of aquatic germplasm resources conservation areas, to the implementation of the spring fishing moratorium, to the complete ban on fishing, but more than two decades. However, conservation not only did not "outperform" the fishing and development of the Yangtze River, but even was far away.
At present, the Yangtze River biocomposity index has reached the worst "no fish" level. The biological integrity index is currently the most widely used aquatic ecosystem health evaluation index, in which the fish biological integrity index grade is divided into excellent, good, average, poor, extremely poor and fish-free from high to low. "Fish don't disappear for no reason, and once they disappear, it means not only that biodiversity is challenged, but also that ecosystems are destroyed." Tang Wenqiao told reporters.
On this year's "World Rivers Day", the "Yangtze River Vitality Report 2020" jointly released by the World Fund for Nature and the Institute of Hydrobiology of the Chinese Academy of Sciences and other 8 scientific research units, the yangtze river vitality index is generally set as "B-", indicating that the Yangtze River is indeed "sick", and the water ecological index of the middle reaches and the "four freshwater lakes" of Dongting, Poyang, Taihu and Chaohu is lower than the overall level of the main stream.
"Whether the Yangtze River is protected or not is no longer a matter of people deciding, but 'the fish have the final say'." In the past, the monitoring of fish stock data in the Yangtze River was mostly carried out by researchers in tandem with fishermen's fishing. With fishermen 'retiring to shore' and dismantling fishing vessels, monitoring models are bound to change, and sampling and data management need to be unified. Tang Wenqiao said. The ten-year ban on fishing in the Yangtze River can allow fish resources to recuperate. Many economic fish in the Yangtze River have a sexual maturity cycle of three to four years, allowing them to reproduce for two to three generations in ten years. ”
In Tang Wenqiao's view, although the discovery of a helio cannot explain too many problems, it undoubtedly released a good signal, and also made people look forward to the protection and recovery of fish in the Yangtze River.
Cure "disease" can not rely on "one party" alone
The ten-year fishing ban provides an opportunity for many Yangtze River "indigenous people" to restore their stocks, but stopping fishing is not enough to get them out of the existential crisis. "It is not realistic to try to cure the Yangtze River by banning the capture of a 'Fangzi.'" Tang Wenqiao told reporters that migratory fish also have to face the reality of habitat fragmentation.
This statement coincides with the judgment of experts at this year's seminar on the conservation of rare and endangered aquatic organisms in the Yangtze River. "Today's disease in the Yangtze River is a cause and a consequence, and it is not objective to think that the fishermen have withdrawn and the disease of the Yangtze River is better."
"Many migratory fish are 'victims' of the jianghu dam project. The arrival of reinforced concrete makes it impossible for fish to return to the spawning ground, and the changes in the flow rate, water temperature and water volume caused by the sluice dam to the river have also changed the living environment of migratory fish eggs and juveniles, further reducing the survival rate of fish. Tang Wenqiao said.
Some people think that more than a decade ago, in order to ensure the normal life, free migration and reproduction of rare wild animals such as Tibetan antelopes, 33 wildlife passages were set up along the Qinghai-Tibet Railway to allow animals to migrate freely. For the protection of fish in the Yangtze River, can this "homework" be "copied"? According to reports, China does have water conservancy projects to build fish migration channels: the first large fish road built by China is the Fish Road of Guangxi Changzhou Water Conservancy Hub Project, with a water level drop of 15 meters between the upper and lower reaches, which can be used by Chinese sturgeon and other fish to reach the upstream by themselves, but at present, the passage of protected rare fish has not been observed. The obstruction of migratory passages does not exist only in China, and the use of fish channels to solve the barriers faced by migratory fish due to water conservancy projects requires a lot of basic research to keep up.
"Ecological dispatch" is a new word thrown out by scientists, which is a measure to use dispatch means to control the decline of water level in reservoirs and create suitable water level and water conservancy conditions for the natural reproduction of fish in the reservoir area. Since 2011, the Three Gorges Reservoir has carried out ecological dispatch experiments to promote the reproduction of drifting eggfish in the lower reaches of Gezhouba for nine consecutive years, and the spawning volume of the "four major fish" (blue carp, grass carp, silver carp and bighead carp) in the Yangtze River has shown an overall upward trend. Ecological dispatch is not only used to help fish breed, but also to meet human needs: in 2014, the Three Gorges Reservoir launched ecological dispatch to suppress the salt tide at the mouth of the Yangtze River and protect the source of Shanghai's grass and sand water.
Actively practice the protection of the Yangtze River
Pan Yingjie, former president of Shanghai Ocean University, told reporters that the effective protection of the Yangtze River estuary is an important link in the protection of the Yangtze River. The hallmark of the health of the Yangtze River ecosystem is the diversity of aquatic organisms, and the key species of this diversity are fish, especially migratory fish and estuarine settler fish, which depend on the ecological environment of the Yangtze River estuary.
Shanghai has always been at the forefront of the protection of the Yangtze River. Since August 2018, the Shanghai section of the Yangtze River has been banned from fishing all year round, and all the fishing vessels of the Yangtze River certified by Shanghai have withdrawn from fishing, completing the 2020 target of the central government's withdrawal from fishing on the Yangtze River ahead of schedule.
On June 6 this year, the Shanghai Municipal Regulations on the Protection and Management of Chinese Sturgeon came into effect. For the first time in the history of local legislation, a law was enacted for "one fish". The promulgation of the "Regulations" means that the protection and management of Chinese sturgeon is no longer a "single soldier", but a systematic protection of all social resources and departments. In the Yangtze River Estuary, an important ecologically sensitive area in the world, as early as four years ago, Shanghai built and put into use the first phase of the Yangtze River Estuary Chinese Sturgeon Protection Base. Today, as an important part of the construction of Chongming's world-class ecological island, the second phase of the base project has officially started construction and is expected to be basically completed in 2021. In the future, it will not only become a base for the artificial domestication and breeding of rare and endangered species in the Yangtze River, but also undertake key science education tasks.
Stocking is also one of the effective ways to promote the restoration of fishery resources. According to incomplete statistics, since the beginning of this year, Shanghai has successively released 2 tons of clams and clams, more than 1.6 tons of ridge-tailed white shrimp, 166,400 juvenile fish of dark-striped oriental pufferfish (that is, puffer fish), 30 Chinese sturgeon, 52,000 cochineals, etc. "The ten-year ban on fishing will help alleviate the crisis of the decline of aquatic biological resources and biodiversity decline in the Yangtze River." The 'combined fist' of 'total ban on fishing + increase and stocking of fishery resources' may play a joint role in the restoration of the ecological environment of the water area and the restoration of biological populations. Pan Yingjie said. It is reported that the Ministry of Communications Jiangkou Waterway Management Bureau and the East China Sea Fisheries Research Institute will continue to carry out the proliferation and stocking of rare wild protected animals, economic species and bait organisms next year.
As the initiator of the ten-year ban on fishing in the Yangtze River, Cao Wenxuan, an academician of the Chinese Academy of Sciences, once said that he hopes to see more than 400 species of fish in the Yangtze River in ten years, and rare aquatic organisms such as Chinese sturgeon and finless porpoises can be well protected. This is also the dream of everyone. In order not to let the Yangtze River white sturgeon become the tomorrow of the helix and the eel, countless people have been working hard...
Xinmin Evening News reporter Gao Yang