Summary

Fish form the major source of animal protein for most rural communities in the Mekong River basin. Recent work by the Mekong River Commission and the fisheries agencies of Cambodia, Lao Peoples Democratic Republic, Thailand and Vietnam have demonstrated that valuable commercial and subsistence fishery stocks undertake migrations significant for survival, growth and reproduction. Barriers to the movements of migratory species are therefore recognised as a key threatening process against the future subsistence and commercial use of these fisheries resources.

Increasing development of the Lower Mekong Basin has resulted in the construction of hundreds of new dams and weirs to provide water for town supply and irrigation. In some areas, these dams have contributed to substantial declines in fish assemblages. It is therefore important that these new structures contain adequate fish passage facilities, such as fishways, to conserve these important subsistence fisheries and maintain species diversity.

Few fishways have been built in the Mekong Basin because they are largely viewed as ineffective or not required by fisheries managers. This view has largely arisen because the few completed fishways were based on designs unsuitable for local fish species. The development of effective fishways is possible, but requires urgent research to determine swimming criteria of Mekong species. These criteria can then be used to develop a management framework aiming to systematically restore fish passage at sites of conservation significance. The development of such a plan would help ensure the long-term sustainability of this socially- and ecologically-important fish community.