Dams on the Mekong River: Lost fish protein and the implications for land and water resources

► We model land and water requirements to replace lost fish protein from proposed dam construction on the Mekong River. ► Estimation for additional water needs for domestic protein production from livestock range from 4% to 17%. ► Estimation for additional pasture land for domestic livestock ranges from 4863 to 24,188km2 (13–63% increase). ► We show considerably higher land and water averages particularly for Cambodia and Laos. ► Consideration is given to significant economic, social and environmental impacts of this protein loss. Proposed dam construction in the Lower Mekong Basin will considerably reduce fish catch and place heightened demands on the resources necessary to replace lost protein and calories. Additional land and water required to replace lost fish protein with livestock products are modelled using land and water footprint methods. Two main scenarios cover projections of these increased demands and enable the specific impact from the main stem dam proposals to be considered in the context of basin-wide hydropower development. Scenario 1 models 11 main stem dams and estimates a 4–7% increase overall in water use for food production, with much higher estimations for countries entirely within the Basin: Cambodia (29–64%) and Laos (12–24%). Land increases run to a 13–27% increase. In scenario 2, covering another 77 dams planned in the Basin by 2030 and reservoir fisheries, projections are much higher: 6–17% for water, and 19–63% for land. These are first estimates of impacts of dam development on fisheries and will be strongly mediated by cultural and economic factors. The results suggest that basic food security is potentially at a high risk of disruption and therefore basin stakeholders should be fully engaged in strategies to offset these impacts.