System structure, natural history, dynamic modeling and adaptive management of the Mekong watershed's Tonle Sap-Great Lake, Cambodia

Cambodian food security has been analyzed from a systems perspective in terms of hydrological, ecological, economic, demographic and nutritional processes. Fish in Tonle Sap Lake and its seasonally inundated floodplain—possibly the world's most productive inland fishery (up to 270 kg/ha/yr harvested)—provides up to 70–90% of all animal protein and fat consumed by over 6 million Cambodians all of whom depend on a rice/fish-balanced diet. Two key factors in this biological production are a flood-pulse-and-expansion process originating from the monsoon-swollen Mekong River and the extent of inundated habitat, including the quantity and quality of vegetation. Water development plans and intensive harvest of the lake's fish and floodplain vegetation endanger protein and fat food security in the Lower Mekong River basin. The Tonle Sap Lake's significance for food security is increasing due to a substantial population momentum phase. Food shortages are likely without an overall framework to understand and manage the interdependencies of this complex ecological and socioeconomic system.; A field assessment of fish and rice food security in the floodplain was made. A system thinking and group model building course prepared Cambodian faculty for their future role in adaptive management of the fishery stocks. The Tonle Area Management Simulation model (TAMS) was developed to simulate primary ecological economic system dynamics. TAMS represents the interdependent behavior of six sectors: hydraulics; vegetative inundation; gross fish production; macro-economic activity; population dynamics and protein nutrition requirements. As an educational tool, TAMS' user-interface allows creation of scenarios based on conceptual trade-offs among the above sectors. As an initial phase of mediated modeling, TAMS provides a format to promote dialogue and group consensus on system behavior among people with interdependent but competing interests that affect fish production, nutritional and economic welfare. Simulations provide insight relating protein deficit to population growth and a smaller flood pulse to fishery economics. Institutional population projections do not account for protein as a limiting factor; the model clearly demonstrates the mortality effect and the fisheries sensitivity to specific natural and human changes.{09}Awareness of and consensus about such issues fosters wiser, better informed decision-making.