The Lancang-Mekong River is one of the most aquatic and biodiverse rivers in the world and is also a famous international river. The upper reaches of the river in China are known as the Lancang River, and after leaving Xishuangbanna, they are called the Mekong River.
Schematic map of the main stream of the Lancang-Mekong River and the whole basin
Foreign researchers estimate that there are 1200 to 1300 species of fish living in the entire Basin of the Mekong River, of which there are more than 850 kinds of freshwater fish, and the richness of species is second only to the Amazon River. There are many high-economic value fish in the Mekong River, such as basa fish, stingray fish, barbed fish, melon fish, etc., and there are also some highly endangered species, such as Irrawaddy finless porpoise, mackerel, koji carp, etc., which have high scientific research and economic value.
For the five river-bearing countries in Southeast Asia, the Mekong is a "treasure river" that creates wealth. In Cambodia, more than 80 percent of the population depends on fish from the Mekong For basic protein needs, while in Laos, 13 percent of the country's GDP comes from the Mekong's fisheries. How important the Mekong River really is, of course, is self-evident.
Mekong estuarine fisheries
<h1>Mekong: The "river of life" of Southeast Asian countries</h1>
The Lancang-Mekong Originates on the Tibetan Plateau in China, passing through China, Myanmar, Laos, Thailand, Cambodia and Vietnam before flowing into the South China Sea. The main stream of the river has a total length of 4,909 kilometers, a basin area of 811,000 square kilometers, and is extremely rich in fishery resources.
According to statistics, the Mekong Basin produces about 2 million tons of wild fish every year, which is quite amazing - you know, the annual catch of the Yangtze River Basin is less than 100,000 tons, and the Yellow River Basin is only about 65,000 tons. In addition, the main economic fish species in the Mekong River are as many as 50 to 120 species, and neighboring countries make full use of these resources to develop aquaculture, which can produce an additional 2.5 million tons of aquatic products every year.
Mekong fishermen fishing in the net
The Mekong River is both a river of life full of wild nature and a river of wealth. In the lower Mekong, the local fishing population exceeds 40 million, and almost 2 out of every 3 people fish for a living. Through the "business" of fishing wild fish alone, residents near the Mekong River Basin can increase their income by 1.6 to 2 billion US dollars.
Among the many fish stocks, the most valuable is migratory fish, which contribute up to 48% of the economy directly. In Cambodia's Tonle Sap Lake and its Klong Waterfall on its border with Laos, almost all of the catch is migratory fish. These fish need to migrate long distances to reproduce their offspring, so the smooth flow of rivers is particularly important.
Hydropower projects are often seen as a reasonable investment for developing countries. It is understood that there are 17 large-scale dam projects that have been built and are being planned in the Mekong Basin, which block the migration channels of fish stocks and inevitably have a fatal impact on migratory fish stocks.
The Mekong catfish is a typical migratory fish, yet over the past 10 years, its population has decreased by 90% due to dam barriers.
Survey data released by the Mekong River Commission (MCR) shows that these dam projects have reduced aquatic life in the Mekong Basin by 40% by 2020; by 2040, 80% of the Mekong's fish resources are expected to be on the verge of depletion. At that time, the fishery resources of countries along the river will face different degrees of decay, ranging from 30% to 55%.
<h1>Hydroelectric dams are extremely harmful to the ecology, so why build them? </h1>
For the development of cascade power plants, there has always been a great dispute in the world. Some developed countries believe that the negative impact of hydropower dams on the ecological environment is long-term, the hydrological environment will change significantly, and many economic fish species will be greatly reduced or even extinct. Most developing countries believe that the establishment of hydropower stations is a practical need to solve the energy crisis and develop the economy, and it is a "rigid indicator" that must be obtained.
Hydroelectric dams on the upper Mekong River
For the neighboring countries of the Mekong River Basin, the primary industry is still a pillar industry, and the energy problem in rural areas is also prominent. In Cambodia, for example, at the beginning of this century, more than 90% of the country's energy came from fuelwood, which will undoubtedly cause great damage to local forest resources and aggravate soil erosion.
From this point of view, the construction of hydropower stations is also partly to protect local forest and land resources. In this way, the construction of hydropower stations has become a dilemma, with fishery resources on one side and land and forest resources on the other, and it is difficult to choose between the two sides.
Residents near Tonle Sap Lake used to fish from the lake for free, but due to the decline in migratory fish, most people now need to pay to buy them
Despite strong international public condemnation, the Mekong River Commission finally decided to build a hydropower station, which has a lot to do with the lancang-mekong power generation potential.
The main stream of the Lancang-Mekong River has reached 5500 meters, of which 5000 meters are concentrated in the Lancang River in China, and the hydraulic resources are quite abundant. Although the water body gap in the Mekong River Basin is not large, due to the large number of tributaries, the hydropower resources contained in it are also considerable, and the total hydropower power exceeds that of the Lancang River, reaching 37 million KW.
Map of the distribution of cascade hydropower that has been built and is planned for the Lancang-Mekong River
In the early days of development, the four major members of the Mekong River Commission (Thailand, Cambodia, Laos, and Vietnam) did not realize the serious ecological consequences of hydroelectric dams, and it was not until 1994 that the impact evaluation of migratory fish was added – but by this time many migratory fish were already in an existential crisis, even to the point of irreparability.
In the 1950s, siamese catfish (scientific name Platytropius siamensis, known in China as knife catfish) was widespread in Thailand's Mekong section, but the species was declared extinct in 2013. The 2018 State of the Mekong Basin Ecological Environment Report notes that 68 of the 692 existing freshwater fish species in the lower Mekong Are in serious existing crisis, meaning that almost 1 in 10 fish species are at risk of extinction.
The Siamese carp, the largest surviving species of carp, is now largely extinct in the Mekong River, which is extremely rare
<h1>In the crisis of the Mekong River, hydropower stations are not "fully responsible"</h1>
In the Lancang River in China, indigenous fish species are also facing an existential crisis.
In the 1970s, experts from the Kunming Institute of Zoology of the Chinese Academy of Sciences traveled to the lower reaches of the Lancang River to collect specimens, and 92 species of fish were found. Later, in 1996 and 2011, experts went to the Lancang River twice to collect samples, but in the end only 64 species were collected, of which the number of large fish such as the Chinese knot fish was significantly reduced, and some plateau fish have basically disappeared.
In contrast, the "ecological disease" of the Mekong River is more serious, and species such as the proto-based, curved carp and toothless fish in the basin are almost depleted, all of which are included in the Red List of Threatened Species by the International Union for Conservation of Nature (IUCN). Coupled with the slow growth and long breeding cycle of these fish, it is difficult for the population to recover, and it is difficult to achieve results through artificial breeding and release.
Endangered species of the Mekong: Aaptosyax grypus
These phenomena are not only due to the construction of cascade hydroelectric plants, but also to the overfishing of fishermen and the use of illegal fishing gear. As mentioned earlier, most people in the Mekong Basin live directly or indirectly from fish stocks, and fisheries are the main source of revenue for millions of local households.
In the past 20-30 years, illegal operations such as electric fish, fried fish and poisonous fish in the Mekong River Basin have been common, and fishing gear with poor selectivity such as purse seines, trawls and drift gillnets is also common. In Cambodia alone, local fishermen use more than 80 different types of fishing gear, and fish of all sizes are caught in one net. These irrational fishing practices eventually led to a sharp decline in natural fishery resources and a continuous decline in the number of species.
Traditional fishing industry in the Mekong
In addition, environmental pollution and the introduction of alien species have also had a serious impact on the local indigenous fish species.
With the continuous development of the economy along the river, the rapid rise of modern industrial and mining enterprises, the significant increase in the use of fertilizers and pesticides, and the large inflow of domestic sewage from residents, these factors will lead to an increase in harmful substances such as oxygen-depleting organic matter and heavy metals in the Mekong River, and eutrophication pollution is becoming more and more serious.
The picture above is a floating market on the Thai river section, and many houses are built directly on the Mekong River, and the resulting domestic garbage pollution is quite serious
As for exotic species, the same cannot be underestimated. For example, in the Lancang River in China, people have introduced small miscellaneous fish such as wheat ear fish and goby fish from other regions, these two kinds of fish are small in size and fast in fertility, and soon became the dominant species in the Lancang River. In the absence of food, these two small trash fish will frantically devour the eggs of other fish, and the small medaka downstream and the Chinese medaka are also endangered.
<h1>summary</h1>
As an important international river, the management of the Mekong River is very difficult, especially for migratory fish resources, and more attention should be paid to cross-regional cooperation and protection. In order to protect the "golden rice bowl" of fisheries, environmental protection and ecological restoration in the Mekong Basin are imperative – which is obviously a big challenge for the four member countries whose economic development is relatively lagging behind.
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