The Yangtze River is sick and needs a ten-year ban on fishing to restore survival. Treatment of diseases first needs to understand the condition, what is the situation in Sichuan, located in the upper reaches of the Yangtze River? In addition to banning fishing, what "prescriptions" will Sichuan prescribe according to its own situation?
"I couldn't see it before, but now I really don't." Du Jun, director of the Fisheries Research Institute of the Sichuan Academy of Agricultural Sciences, said that a big fish caught in the past was heavier than the fish caught in a net now, and now a few pounds is a big fish. The most recent comprehensive fish census in the Yangtze River Basin dates back to the 1970s, when "historically, there were more than 240 species of fish distributed in Sichuan. Nearly half of them have been rare in the last decade."
During this period, the fishery authorities at all levels in Sichuan have also been constantly trying to restore the abundance of fish, implementing a system of fishing bans from March to June every year, as well as measures such as the proliferation and stocking of economic fish to rare fish. "It can only be said that the recession has been slowed down." Du Jun said.
Somewhat surprisingly, many fish that disappeared from the water have been "revived" on the shore. From the Jiangtuan in the 1980s, to the "water tiger" Sichuan-Shaanxi Zheluo salmon in recent years, the "giant panda in the water" Yangtze River sturgeon, etc., through the efforts of the Fisheries Research Institute of the Sichuan Academy of Agricultural Sciences and other relevant units, about 30 or 40 species of fish that disappeared in the river have "landed", and these fish have survived through artificial preservation and breeding.
The ten-year ban on fishing in the Yangtze River is two words for these fish: go home.
Nearly half of the more than 240 species of fish have disappeared
"In the past, fishing boats were still big and small, and the big boats caught 40 to 50 to 70 or 80 pounds of big fish, and sometimes they could encounter more than 100 pounds." Du Jun recalled that in recent years, there have been few big boats, because there have been no big fish in the river for many years. Now a few pounds of individuals are already considered big fish, at least a net is empty, most of the time a net of fish caught is not as heavy as a fish in the past when it was good.
Yangtze
The most recent comprehensive fish census in the Yangtze River basin dates back to the 1970s. The ban on fishing and retiring from the Yangtze River involves 45 aquatic biological reserves in Sichuan Province and the main stream of the Yangtze River, the Min River, the Tuo River, the Chishui River, the Jialing River, and the Dadu River (commonly known as "one river and five rivers"). "As far as fish species are concerned, there are basically only yunnans in the country than sichuan." Du Jun said that the fish distributed in Sichuan are mainly warm and cold water fish, and there are tropical fish in Yunnan.
"At its peak, there are about 240 species of fish in the Yangtze River basin in Sichuan. Nearly half of them have been rare in the last decade. Du Jun said that 110 of the more than 240 species of fish are economic fish; more than 40 rare fish include protecting wild fish protected at the national and provincial levels; and there are about 100 species of endemic fish in the upper reaches of the Yangtze River. Nearly half of the disappeared fish are rare and endemic. In addition to the Chinese sturgeon, white sturgeon, Yangtze River sturgeon, which have a high degree of attention, there are also fish such as river groups that often appear on everyone's table, and it is very difficult to find their traces in the wild.
Long-snout is commonly known as Jiang Tuan
Rouge
Taking the familiar Jiangtuan as an example, in the late 1970s and early 1980s, "the professional fishing teams in Leshan, Luzhou and Yibin did not catch a single river regiment for two whole days." Du Jun recalled that the Fisheries Research Institute of the Sichuan Academy of Agricultural Sciences currently has two bases, one in Chengdu and one in Yibin. The predecessors of these two bases are the Sichuan Jiangtuan Test Site and the Sturgeon Stocking Station.
The Invisible "Man In and Out"
"Compared with people on land, people who enter and retreat, invisible people who enter and retreat are more likely to be ignored." Lai Jiansheng, deputy director of the Aquaculture Technology Research Office of the Fisheries Research Institute of the Sichuan Academy of Agricultural Sciences, said that human activities such as the development of coastal industries, the expansion of cities and the construction of hydropower stations have destroyed the living environment of fish. For example, fish such as the Chinese sturgeon, which need to migrate to a fixed area to spawn, are affected by the dam of the hydropower station that blocks the migration route, resulting in the impact of their reproductive activities.
If terrestrial animals can still retreat, then the fish in the water really have no way to retreat. Because the entire aquatic environment is integrated with each other, just like the ripples produced by stones thrown into the water, they will be affected everywhere. The environment is damaged and the food chain is missing, which is a disaster for fish at the top of the food chain such as the Yangtze River sturgeon. Once the fish at the top of the food chain are absent, the entire aquatic ecology will be in a dangerous state of loss of control. Just like the grasslands without wolves, rat infestation is rampant.
Released into the Yangtze River sturgeon
"Various measures to restore the water ecological environment have not stopped, but objectively speaking, it can only be said that the trend of decline has been slowed down." Du Jun said that the demarcation of protected areas is one of the most important measures. In addition, there are measures such as setting a fishing ban period and increasing and stocking. Sichuan first placed economic fish, and by around 2004, it began to release rare fish. "It's much better now, before the upstream was released, the downstream 'harvest'", the fish that grow in the pond, just into the river, will habitually gather on the shore. Stocking activities are generally carried out in June, while the previous closure period was not so long, and was later extended to the end of June, providing a buffer time for fish to adapt.
Lai Jiansheng said with a smile that now everyone's sense of protection is getting stronger and stronger. Many scientific research units have been reported by local residents when conducting fishery resource surveys, and "local residents think they are fishing.". Such a change Du Jun is also deeply impressed, "in the earliest days, to check the fishing boats must shout the public security 'support', otherwise the fishermen will not listen at all", now in addition to the water environment itself, there is also people's consciousness. This is very important for the ban on fishing in the Yangtze River. "The ban on fishing in the Yangtze River is a long-term thing, in a few years there may be more fish, some people may use their brains, and mass supervision is also the key to the ban on fishing in the Yangtze River."
"Ashore" the Yangtze River sturgeon on the way home
From people entering and retreating to fish with no way out, can the more than 100 species of fish that disappeared in Sichuan only appear in books or tv networks in the future? Surprisingly, while the number of fish in the water is decreasing, the number of fish "ashore" is increasing. From the jiangtuan that broke through the artificial breeding technology in the 1980s, to the artificial breeding of the "water giant panda" Yangtze River sturgeon for the first time in 2012, and then to the breeding of the "water tiger" Sichuan-Shaanxi Zheluo salmon. Whether it is quantity, or quality, wild fish artificial breeding, Sichuan has always been at the forefront of the country, "is not the first uncertain, the top three are definitely no problem."
On March 11, 2020, in Jiajiang County, Leshan City, Sichuan Province, researchers collected data on the activity trajectory of Yangtze River sturgeon in 20 lakes within the Yangtze River sturgeon stocking plan
Du Jun said that the yellow jaw fish commonly known as the yellow spicy ding, more than 60% of the country's yellow jaw fish fry, and nearly half of the commercial fish are produced in Sichuan. There are more river groups, and the production of fry and commercial fish exceeds 60%. "In addition to the four big fish, the amount of food in the river group can basically rank in the top few." At present, through technological breakthroughs, there are about 40 kinds of aquatic animals such as fish that have been artificially bred in Kawauchi, including ya fish, giant salamander (also known as baby fish), cochineal fish, largemouth catfish and so on. Among them, more than ten species have been formed on a large scale. Since its establishment in 1977, the Fisheries Research Institute of Sichuan Academy of Agricultural Sciences has successfully migrated and domesticated more than 10 kinds of rare and endemic fish such as Chinese sturgeon (national level one), Dashi sturgeon (national level one), and rouge fish (national level two); it has taken the lead in successfully completing the research on the migration and domestication and artificial breeding technology of rare and endemic fish such as largemouth catfish, long-snouted catfish, long loach, Iwahara carp and central warsaw loach, and promoted and applied it nationwide.
Can the problem of reducing fish species be solved by returning to the water after successful artificial breeding? "Theoretically, this is true, but the fish that need to 'go home' need to survive and breed the next generation, not rushing passers-by, otherwise it is just a lively bubble." Lai Jiansheng said that the artificially bred Yangtze River sturgeon has been successfully bred for three generations, which is equivalent to the four generations of people in the same house. However, after 2000, no naturally reproducing juvenile Yangtze River sturgeon was found in the entire section of the Yangtze River. From the first release of 30 to 40 cm of juvenile fish, to about 1 meter long sexual mature adult fish, and then to the early March this year, 20 yangtze river sturgeon that were bred under artificial conditions and "have been parents", a 12-kilometer test area in the main stream of the Tsing Yi River.
How is the Yangtze River sturgeon back home and how long will it take to settle down? "This year's floods are more severe, and they may have been washed away." Lai shook his head and said that the sonar devices had not received their signals recently and needed to be confirmed. What can be done at present is to expand the artificial breeding population as much as possible under the conditions of artificial reproduction. It takes 6 to 8 years for the Yangtze River sturgeon to mature sexually, which means that everything is in the most ideal situation, and the first generation of the Yangtze River sturgeon released, that is, the first indigenous Yangtze River sturgeon in the river section, will take about 8 years to grow up until they can reproduce their offspring.
Yangtze River sturgeon
Regardless of whether the wild release test of these 20 Yangtze River sturgeon is successful, the pace of the Yangtze River sturgeon returning to nature will not stop. "The Yangtze River has been closed to fishing for ten years, and their descendants may have the ability to breed in the wild." At the same time, their home, the Yangtze River, is also expected to return to the memory of the fish.
Red Star News reporter Lin Cong
Edited by Liu Yupeng
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