Fish assemblages and first sale prices from local markets in the Lower Mekong River Basin

The Mekong River is the most productive inland fishery in the world and identified as a valuable source of hydropower generation. Consequently, benefits of energy production must be traded off against impacts on other ecological and environmental services, especially on fisheries that have been largely downplayed. We surveyed fish markets in 12 provinces in the Lower Mekong River Basin (LMB) to quantify the diversity, abundance and prices of fish species and to account for potential impacts of water infrastructure and development projects. Of 116 species in nine major ecological guilds in markets, potamodromous main channel spawners were the most diverse guild that contributed 30% of species and were present in markets in all countries and sites, whereas anadromous species were the least diverse guild with two species in Vietnam only. More than 45% of fish recorded in local markets in Cambodia and more than 80% in Vietnam were small‐sized fish (<25 cm), whereas about 50% of fish marketed in Lao PDR and Thailand were large‐sized fish (>50 cm). Fish were sold by both size and species, with most species sold in only one size category. The first‐sale price was highest in Lao PDR, followed by Thailand, Vietnam and Cambodia. Our findings provide primary ecological and economic information that can be used to estimate potential economic losses of fisheries when considering trade‐offs between energy and the environment.