Mekong Fishes: Biogeography, Migration, Resources, Threats, and Conservation

The Mekong, the largest river in Southeast Asia, is of fundamental cultural, ecological, and economic importance to the entire Mekong region. It supports the highest fish diversity after the Amazon and the largest inland fishery in the world and is at serious threats of intensifying environmental disaster and human activities. Mismatched the high attention worldwide, few related studies were concerning fishes in the whole basin. In this paper, 899 freshwater fish species were recorded, which could be grouped into 9 biogeographical regions based on their distribution information; each region owed its unique fauna with different dominance/or endemism at the genus level. The species richness was positively related to temperature, precipitation, and longitude, but negatively to latitude and slope. Seven migratory systems were deduced from spatial distribution information of 321 migratory species, and these systems were separate but not independent. Mekong fisheries were highly diversified with an estimation of a maximum worth of around $17 billion. Fisheries played an irreplaceable role in Cambodia, and aquaculture was of growing importance in the Delta and the Upper Mekong. Cascade dams, as well as climate change, overfishing, aquaculture, and pollution, posed threats to fish diversity and resources by habitat homogenization, migratory channel blockage, parents population decline, and diseases. Integrated management, a combination of capture and aquaculture fisheries, and collaboration among scientists, fishermen, and the public were advocated to address the issues facing Mekong fishes.