Research status of the Lancang-Mekong River Basin: fish and environmental stressors

The Lancang-Mekong River, the largest river in Southeast Asia, supports high biodiversity of fish but has also suffered from intensive human- and nature-induced stressors for decades, and it is feared that this trend will continue in coming decades. Although the river has received wide attention from researchers, spatiotemporal trends in fish diversity and production and of environmental stressors within the catchment remain unclear. Also, an overview of current knowledge for catchment-scale sustainable management is lacking. This study analysed research publications related to Mekong fishes and threats, and identified knowledge gaps and limitations in current research. We found an increasing trend in studies on fish and/or environmental stressors, but that some research themes, including dam construction, pollution, infectious disease, and salinization, vary across regions. In general, research foci were determined by geographical location, fish diversity, and environmental stressors in each region. For fish-related studies, research in the Upper and Middle Lancang-Mekong regions was mostly related to the conservation of wild fish populations and communities, while in the Mekong Delta, a large proportion of studies were related to fish farming. For studies related to environmental stressors, current research foci were mainly on persistent threats, including flow modification, pollution, habitat degradation, and overexploitation. However, coverage of some newly emerging threats, such as microplastic pollution and harmful algal blooms were lacking. This study helps provide a better understanding of factors impacting the Lancang-Mekong River and its fish communities, and provides a basis for future research, management, and conservation actions.