information:classification, information:highlighting, stylistic:tone
Fisheries

Aquatic biodiversity in the Mekong River system is the second highest in the world after the Amazon. The Mekong boasts the most concentrated biodiversity per hectare of any river. The largest recorded freshwater fish, a 300 kg giant freshwater stingray in 2022 and previously a 293 kg Mekong giant catfish in 2005, were both caught in the Mekong River.

The commercially valuable fish species in the Mekong are generally divided between "black fish", which inhabit low oxygen, slow moving, shallow waters, and "white fish", which inhabit well oxygenated, fast moving, deeper waters. People living within the Mekong River system generate many other sources of food and income from what are often termed "other aquatic animals" (OAAs) such as freshwater crabs, shrimp, snakes, turtles, and frogs.

OAAs account for about 20% of the total Mekong catch. When fisheries are discussed, catches are typically divided between the wild capture fishery (i.e., fish and other aquatic animals caught in their natural habitat), and aquaculture (fish reared under controlled conditions). Wild capture fisheries play the most important role in supporting livelihoods. Wild capture fisheries are largely open access fisheries, which poor rural people can access for food and income.

Broadly, there are three types of fish habitats in the Mekong: i) the river, including all the main tributaries, rivers in the major flood zone, and the Tonle Sap, which altogether yield about 30% of wild catch landings; ii) rain-fed wetlands outside the river-floodplain zone, including mainly rice paddies in formerly forested areas and usually inundated to about 50 cm, yielding about 66% of wild catch landings; and iii) large water bodies outside the flood zone, including canals and reservoirs yielding about 4% of wild catch landings.

The Mekong Basin has one of the world's largest and most productive inland fisheries. An estimated two million tonnes of fish are landed a year, in addition to almost 500,000 tonnes of other aquatic animals. Aquaculture yields about two million tonnes of fish a year. Hence, the lower Mekong basin yields about 4.5 million tonnes of fish and aquatic products annually. The total economic value of the fishery is between US$3.9 and US$7 billion a year. Wild capture fisheries alone have been valued at US$2 billion a year. This value increases considerably when the multiplier effect is included, but estimates vary widely.

An estimated 2.56 million tonnes of inland fish and other aquatic animals are consumed in the lower Mekong every year. Aquatic resources make up between 47 and 80% of animal protein in rural diets for people who live in the Lower Mekong Basin. Fish are the cheapest source of animal protein in the region and any decline in the fishery is likely to significantly impact nutrition, especially among the poor. Fish are the staple of the diet in Laos and Cambodia, with around 80% of the Cambodian population's annual protein intake coming from fish caught in the Mekong River system, with no alternative source to replace it. An MRC report claims that dam projects on the Mekong River will reduce aquatic life by 40% by 2020, and predicted that 80% of fish will be depleted by 2040. Thailand will be impacted, as its fish stocks in the Mekong will decline by 55%, Laos will be reduced by 50%, Cambodia by 35%, and Vietnam by 30%.

It is estimated that 40 million rural people, more than two-thirds of the rural population in the lower Mekong basin, are engaged in the wild capture fishery. Fisheries contribute significantly to a diversified livelihood strategy for many people, particularly the poor, who are highly dependent on the river and its resources for their livelihoods. They provide a principal form of income for numerous people and act as a safety net and coping strategy in times of poor agricultural harvests or other difficulties. In Laos alone, 71% of rural households (2.9 million people) rely on fisheries for either subsistence or additional cash income. Around the Tonle Sap Lake in Cambodia, more than 1.2 million people live in fishing communes and depend almost entirely on fishing for their livelihoods.