"If you don't enter the pond, you can't eat fish and turtles."
This famous quote from Mencius vividly describes the abundant fish resources in the waters of the Yangtze River 2,500 years ago.
In those days, fishermen almost walked on the backs of fish, but time has passed, and now this sentence is more like a satire on the ecology of the Yangtze River.
At the beginning of 2020, the news that the Yangtze River has been "fishless" on the Internet once attracted widespread attention;
The Yangtze River basin is rich in aquatic resources, there are many kinds of fish, as early as the Han Dynasty, there is a record of "fish fat in the river" in the "Wu Di Ji".
According to incomplete statistics, 426 species of fish have been found in the Yangtze River system, accounting for about 56% of China's freshwater fish.
Among them, there are nearly 150 endemic species.
In the 50s of the 20th century, the fishery output of six provinces and cities in the Yangtze River basin reached 450,000 tons at its peak, and it was called a "natural fishing ground".
At that price, its fishery output value was about several billion yuan, accounting for more than 1/10 of the country.
This is mainly due to the vast area of lake water bodies such as Dongting Lake and Poyang Lake of the Yangtze River and its main tributaries, which provide good conditions for the survival and reproduction of fish.
In the 1950s, the catch of the four major carp in Dongting Lake alone was as high as 130,000 tons.
In terms of important economic fish, sturgeon, shad, yellow eel, finless porpoise and so on are all widely distributed.
At that time, fishermen often joked that "if you throw a stone, you can fill a whole basket of fish", which is not an exaggeration, but a true portrayal of the abundance of fish resources in that era.
However, the good times were short-lived, and from the 60s of the 20th century, catches began to decline due to overfishing and habitat destruction.
By the 80s, it had dropped to about 200,000 tons, and in the 90s, it was only 100,000 tons, and most of them were small, low-value fish.
Among the small fish, crucian carp, bream and other pollutant-tolerant species occupy a major position.
Many large economic fish are on the verge of extinction, such as the anchovy, one of the "Three Fresh Fish of the Yangtze River", which had a catch of more than 10,000 in the 70s, and now only a very small number of scattered individuals remain, and the basic disease has lost its economic value, and the white sturgeon was confirmed to be extinct in the wild in 2003.
In the face of such a grim situation, in 2020, the Ministry of Agriculture and Rural Affairs announced a 10-year ban on fishing in key waters of the Yangtze River basin from January 1, 2021, hailed as the "strictest in history" fishing ban, hoping to reverse the depletion of fish stocks through strict protection measures, but it is uncertain whether it will be effective in 10 years, and the future fate of Yangtze fish is worrying.
There are many reasons for the decline of fish in the Yangtze River, which can be summarized in three main categories: overfishing, environmental pollution and habitat destruction.
The first is overfishing.
After the reform and opening up, the Yangtze River basin has developed rapidly, and a large number of aquaculture and fishing industries have emerged.
There are as many as 140,000 registered fishermen and more than 30,000 fishing vessels, not counting the many unregistered artisanal fishermen.
A large number of fishing gear has been put into use, which seriously exceeds the carrying capacity of fish stocks.
Taking Poyang Lake as an example, the area of fish farms established in the 80s of the 20th century exceeded 1/10 of the lake's area, and a large number of swamps in the lake were confiscated as breeding ponds, destroying the spawning grounds of fish.
At the same time, the excessive use of chemicals also causes poisoning to aquatic life.
As a result, since the mid-80s, the catch of Poyang Lake has continued to decline, and the main economic fish has decreased by more than 70%.
In the Yangtze River basin alone, in recent years, there have been an average of tens of thousands of illegal activities such as electric fish every year, and these extremely unenvironmentally friendly fishing methods have damaged the reproductive system of fish, and a large number of juveniles and hatched larvae have been caught by mistake.
This is followed by environmental pollution and habitat destruction.
A large amount of domestic sewage from industry and urban areas has been discharged, and the water quality has deteriorated, and sediment has accumulated and the area of rivers, lakes and lakes has shrunk.
All of these have seriously affected the water environment on which fish depend.
The accumulation of heavy metals and organic pollutants, which are also enriched into fish through the food chain, endangers the aquaculture industry, which is an important ecological cause of fish decline.
In addition, the construction of man-made water conservancy projects, such as hydropower stations, sluice dams, and embankments, has blocked the migration of fish to a certain extent.
This puts a strain on the survival of many long-range migratory fish.
After the completion of the Three Gorges Project, the water level and water quality of Poyang Lake and Dongting Lake, important lakes in the Yangtze River basin, have changed, affecting the growth cycle of fish.
Climate change is also an important factor affecting fish in the Yangtze River.
According to monitoring, the average annual temperature in the Yangtze River basin has increased by 0.29°C in the past 30 years, which is greater than the national average.
In addition, climate warming also leads to changes in river flow and dry seasons.
In addition, the construction of the project to impound the river channel has led to serious sediment accumulation, and the shrinkage and shallowness of rivers, lakes and lakes.
This has reduced the area of wetlands where fish live, and some migratory fish that depend on water have also been reduced due to deteriorating habitat conditions.
The negative impact of climate change on the ecological environment of the Yangtze River is complex and deserves our great attention.
In terms of ecological impacts, more than 90 species of fish in the Red List of Species in the Yangtze River and its tributaries have been classified as endangered or vulnerable, indicating that the entire river ecosystem is suffering serious damage.
One of the most striking is that several "flagship species" are on the verge of extinction, and the white sturgeon has not been found in the wild since 2006 and can be considered extinct.
The number of finless porpoises has plummeted by nearly 90%, leaving only about 1,000 individuals, and there is a danger of functional extinction.
The disappearance of these large apex predator species has disrupted the original food chain structure and energy flow of the Yangtze River ecosystem, and its impact is comprehensive and imperceptible.
In addition, some invertebrates such as Chinese mitten clams and hairy crabs are also endangered, and some have become extinct in the market.
This is a positive reflection of the degradation of the entire river's ecological environment.
We have reason to worry that if effective measures are not taken as soon as possible, the Yangtze River biome may irreversibly mutate or even collapse in this century, which will be an ecological disaster for the entire Chinese nation.
The decline in fish in the Yangtze River basin has seriously affected the industries and livelihoods of the people involved.
Millions of fishermen in the region depend directly or indirectly on the fishery for their livelihoods, and the sharp decline in fish populations has taken a heavy toll on their livelihoods.
Xuyi County, Jiangsu Province, was once a county because of the fishing industry, known as "China's fishing town", but in recent years, the fish catch has plummeted, fishermen's income has plummeted, many fishermen have left their hometowns to work, and the original land of fish and rice has become increasingly decaying.
This is just a microcosm of the countless fishing villages and fishermen along the Yangtze River, and some counties and cities around the lake are also facing serious structural unemployment in the fishing industry, such as the Dongting Lake area, where more than 100,000 fishermen are facing a job loss crisis.
Some local governments have tried to help employment through subsidies and tourism tours, but they have not been able to solve the problem fundamentally.
What is more worthy of reflection is that in the past, our understanding and attention to the resources and environment in the Yangtze River were seriously insufficient, which led to the grim situation of today's fish resources on the verge of collapse.
As early as the 90s of the last century, scholars and experts in the Yangtze River basin began to call for attention to the protection of aquatic biological resources.
They pointed to a downward trend in fish catches, warning that it was a sign of degradation of the entire ecosystem, but the response from government departments and all sectors of society was slow.
It wasn't until the problem had already seriously affected the livelihoods of fishermen that my generation really realized that urgent measures had to be taken.
The 10-year fishing ban imposed in 2020 can be said to be a last resort.
This reactive response may be a step too late, but it is still the last chance to save the ecology of the Yangtze River.
This requires the support and cooperation of the whole society, and the strict implementation of the fishing ban policy, so that the Yangtze River has time to breathe and recover itself.
At the same time, scientific research continues to be invested.
Good conditions for fish reproduction are created through measures such as artificial breeding and release, construction of standardized fishing grounds, and regulation of the water environment.
In the future, gene editing technology is also expected to be applied to breed excellent strains, and we are confident that this seemingly dead mother river will be revived and surging endlessly.
Of course, protecting the environment is not achieved overnight, and requires national action.
As ordinary citizens, we should also start from our daily lives to spread the concept of environmental protection, save resources and eliminate pollution.
Only the unity of nature and man can successfully complete this life test of environmental protection.
Resources:
MA Aiping. The Yangtze River basin will be banned from fishing for ten years[N]. Science & Technology Daily,2019-12-18(003).
Xie Ping.The biodiversity crisis of the Yangtze River: water conservancy project is the culprit, and the cool fishing is the accomplice[J].Lake Science,2017,29(06):1279-1299.)
LIU Fei,LIN Pengcheng,LI Mingzheng,GAO Xin,WANG Chunling,LIU Huanzhang.Current status and conservation measures of fish resources in the Yangtze River Basin[J/OL].Chinese Journal of Hydrobiology:1-13[2020-08-18]