In June 2022, fishermen catch a 4-meter-long, 2.2-meter-wide stingray weighing 300 kilograms in Cambodia's Mekong River. This is the largest of the surviving freshwater fish to date.
The Cambodian stingray broke the record for the largest freshwater fish, the last record set by a Thai catfish. The giant catfish caught in the Mekong River in Thailand in 2005, 2.74 meters long and weighs 293 kilograms, this stingray weighs 7 kilograms, setting a new record for catfish.
Fishermen and biological research teams wrapped tarp tabs around the stingray and hoisted it from the water onto a scale, accurately weighing the large fish. Giant stingrays are not uncommon, and just a month ago, in May 2022, fishermen caught another stingray weighing 180 kg nearby.
The Mekong River flows through many countries, and in the same river of different countries, there are a variety of huge freshwater fish, including giant stingrays, giant catfish, and giant Siamese carp.
Regarding these big fish in the Mekong, let's start at the beginning.
The Mekong River, which produces the largest freshwater fish
The Mekong River is 4,909 kilometers long and flows through China, Myanmar, Laos, Thailand, Cambodia and Vietnam, and flows into the South China Sea.
The upper basin of the Mekong River originates from the Mainland's Qinghai-Tibet Plateau and is called the Lancang River, which is called the Mekong River when it flows into the lower basin.
The Lancang River originates in the Tanggula Mountains of Qinghai Province, flows through Tibet and Yunnan, and enters Myanmar from Xishuangbanna. The area through which the Lancang River flows is steep and narrow, and the flow of tributary water is very small. Only after reaching Xishuangbanna did the river widen and slow down. The amount of water in the upper basin is about 15 to 20% of the entire river.
After the Lancang River enters Myanmar, it comes to the lower basin, called the Mekong River. The area where the Mekong River flows is gentle and converges more of the surrounding tributaries. By the time it enters Cambodia, the Mekong River has pooled 95% of its water.
Most amazingly, the Mekong River is not an inaccessible river hidden among the mountains, but a river that runs through densely populated areas. Faced with the crisis of hydropower damming, sand dredging, industrial sewage discharge, and overfishing, the Mekong River still produces a wide variety of aquatic organisms, including the world's largest freshwater fish.
The Mekong has the most concentrated biodiversity per hectare of rivers. The Mekong river has the highest yielding inland fisheries in the world, including wild-caught and aquaculture. For people living in downstream watersheds, fish is their staple food. It is estimated that 80% of cambodia's annual animal protein intake comes from fish caught in the Mekong.
Giant fish, giant stingrays, giant catfish and giant Siamese carp live in the gentle lower Mekong river basin.
Giant stingray
The giant stingray looks like a fan with a thin tail like a whip inserted into the fan, and the tail is about twice as long as the body of the disc.
Stingrays eat small fish and crustaceans, molluscs. In the skin of its abdomen, there is a network of pores filled with mucus, called the ampullary abdomen. The belly of the pot can detect the electric field in the water, helping the stingray to find small fish and shrimp, and prey on prey.
Stingrays are mild-mannered fish that do not actively attack humans. It has 2 defensive moves, one is buried in the soil, and the other is to resist with stingers. It buries it in the mud at the bottom of the river, and it is difficult for fishermen to drag it out of the sand when fishing. In addition, on its tail, there is a jagged thorn that is covered with poisonous mucus. This stinger is very hard and can penetrate the enemy's body and give him a fatal blow.
Mekong giant catfish
In 2005, on the Mekong River in northern Thailand, it took five boatmen an hour to catch a giant catfish. After the fishing boats dragged the catfish back to shore, it took 10 people to carry it ashore.
When the cut catfish is sold, fishermen weigh out its weight, 293 kg. This catfish was not only the heaviest catfish in the world, but also the heaviest freshwater fish of its time.
Giant catfish that live in the Mekong River are endemic species to the Mekong River. Unlike other catfish, the Mekong giant catfish have no teeth and no catfish whiskers. When it is a small fry, it not only eats zooplankton, but also cannibalizes. But after a year, giant catfish become herbivorous, feeding on plants and algae in rivers.
Giant catfish grow fast, and wild catfish can reach a weight of 150 kilograms by the 5th year. Giant catfish are very popular with fishermen, not only can eat a lot of meat, but also can be used to refine oil, weighing more than 100 kilograms of giant catfish can produce a lot of fish oil.
Overfishing, coupled with the construction of hydroelectric dams, has led to a sharp decline in the mekong giant catfish population, which has fallen by more than 80 percent over the past 14 years and become endangered. Now Thailand has banned the predation of wild giant catfish, and the giant catfish in the market is an artificially farmed species.
Giant Siamese carp
The giant Siamese carp, the largest species of carp in the extant carp family, lives in the Mekong River Basin.
Giant Siamese carp is a herbivorous migratory fish that swims slowly and feeds on algae, phytoplankton and fruit that falls into rivers. Compared to other carp, it has a particularly large head and no carp whiskers.
Giant Siamese carp are said to have grown up to 3 meters long and weighed 300 kilograms, but there is no definitive data for this record. Pictured is a giant Siamese carp caught by a British angler in Thailand in 2016, weighing 100 kilograms.
Like the situation of giant catfish, the number of giant carp is declining sharply. In 1964 Cambodia caught a total of 200 tons of giant carp, by 1980 only 50, and by 2000, only 10 had been caught. Since 1994, Cambodia has not been able to catch a giant carp weighing more than 150 kilograms.
Like the giant catfish, the giant Siamese carp is endangered. Now, the giant carp sold in the market are all artificially farmed products. This giant Siamese carp weighs 115 kg.
summary
Back to the beginning, cambodia's largest stingray. After weighing, fishermen and research teams put it back into the Mekong River.
The purpose of finding the largest freshwater fish is not to record a data, but to record the ecological environment. The presence of giant fish is an indicator of the health of aquatic ecosystems.
Most of our current research on large river ecosystems is in rivers located in temperate regions. In contrast, the Mekong river is tropical, with frequent seasonal floods, and a variety of water volumes and tributaries that bring more vitality to the Mekong. However, due to hydroelectric dam construction and overfishing of fisheries, large freshwater fish stocks in the Mekong have generally declined. The population of many species of large fish is declining, just as giant catfish and giant carp are in danger of endangerment.
Protecting the big fish is also protecting the ecosystem of the river and guarding our homeland.
Protecting the world's largest fish and allowing it to grow healthily is what it means to find the largest freshwater fish.
Well, the secret of the largest freshwater fish is here first.
Follow the French is Bacon and explain the secrets of nature to you, see you in the next issue.
Resources:
1、 World's largest freshwater fish found in Mekong, scientists say
2、Giant River Stingrays Found Near Thai City