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Making the most of the Mekong

Mighty, murky and magnificent, the Mekong is one of the top ten rivers of the world. It rises in the mountains of southern China and flows through Laos, Thailand and Cambodia to Vietnam where it reaches the South China Sea. Sixty million people depend directly upon this river for their livelihoods and perhaps as many as 300 million depend upon what is produced within the Mekong River basin. Decisions affecting the flow and the flood can have a profound impact upon the productivity of its waters but, without a clear understanding of the relationship between the life of the river and the livelihoods of the people, how can the best use be made of the Mekong?

Sun-dried fish from the Mekong
Credit: Eric Baran, ICLARM

Every year, between June and December, the river floods to about thirty times its low season size. More than 84,000 km2 are flooded, an area equivalent in size to Uganda. The great lake in Cambodia, Tonle Sap, acts like a sponge for the river basin, expanding from 5,000 km2 to 15,000 km2. The floodwaters, far from bringing destruction and despair, are welcomed because they fertilize the soil, replenish the water table and trigger the migration of fish to breeding and feeding grounds within the inundated forests and riverine wetlands. These provide a rich soup of nutrients upon which the fish feed and grow. As the floodwaters recede, the fishermen of the region work together constructing what are, in effect, long bamboo fences around the lake to trap the migrating fish. The fences stretch for some 1,500 km, using 3 million stakes or more. Huge quantities of fish are caught - around 30 tonnes an hour in one single fishery. Although this is not industrial fishing in the accepted sense, it is artisanal fishing on a massive scale and a truly impressive sight.

More of less

It is now estimated that the total fish catch from the Lower Mekong Basin is two million tonnes per year. But local people say that now dominant species are small fishes that mature early and at a very small size. Generally speaking the catch per fisherman is smaller than in the past, although the overall catch is larger than before because more people are fishing. The river and its wetlands are also harvested for frogs, snails, crabs and other aquatic delicacies. But, as with any other major river system, there are competing demands for its use. Farming families, even in large numbers, who grow a little rice, raise a few chickens and catch fish for a living, tend to get overlooked when more powerful interests are represented. The Mekong is no exception. And it is not only the uses to which the river itself is put. If the forested wetlands, for example, are cleared for rice production, this could have a big impact on the size of the fish catch.

After decades of conflict and isolation in the region, the last few years have seen attention turning to the opportunities that peace makes possible. There are new regional and international markets developing and, to serve them, rising demands for irrigation water for agriculture, for industry, for power generation, for transport and for domestic use. The countries along the upper reaches, particularly Laos, need the energy that the river could provide, and the foreign exchange that selling that energy could earn. Over the last thirty years, thirteen major dams (>10MW) and several thousand small reservoirs (Cambodia 800, Lao PDR 600, Viet Nam 600, Thailand 4 000) have been built across the Mekong and its tributaries, and more are planned. Governments need to weigh up the options and reach decisions that maximize the opportunities and minimize the risks. Everyone wants development, but not at the expense of the livelihoods of people who depend upon the common property resources of the river.

In some respects the Mekong is unusual, and fortunate, in that Laos, Thailand, Cambodia and Vietnam cooperate on issues relating to the river through the Mekong River Commission. But the recent history of the region means that much of the data, upon which models for predicting future trends must be based, is of poor quality or entirely missing. A number of national and international institutions, including ICLARM - The World Fish Center, and IWMI, the International Water Management Institute, have been working with the Mekong River Commission to develop models that the governments in the region can nevertheless use to simulate the effects of hydrological modifications and other activities on fish productivity and the riverine ecosystem. The very complex relationship between the hydrology of the basin and the abundance of fish must be understood. For instance the fish abundance depends on the flood level, but also on the flood duration. When the flood starts and whether it is regular or not are also influential factors. However all these factors remain to be quantified. How many people dependent upon fisheries would hydrological modifications affect?

IWMI has produced the first comprehensive hydrological model of the Mekong including the Tonle Sap system. ICLARM's priority has been to demonstrate potential risks to the sustainability of fisheries and the impact that they would have on livelihoods. Hydrology and ecology must also be linked to social and economic factors and, in turn, to policy. It may be complicated and difficult but a free flow of useful information will help everyone concerned to make the most of the Mekong.

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