Environmental Quality Impact on Shrimp Farming in the Mekong Delta (Vietnam), Using Statistical Analysis and GIS

Jacques Populus (1), Phuoc Hoang Son Tong (2), Pascal Raux (3), Raweewan Nutpramoon (4), Jean-Louis Martin (1), Yves Auda (5)

(1) Ifremer, DEL/AO, Centre de Brest, Plouzané (FR)
(2) Institute of Oceanography, Nha Trang (VN)
(3) CEDEM, Brest, (FR)
(4) GISTDA, Bangkok (TH)
(5) Cesbio-Ladybio, Toulouse (FR)

Over the last twenty years, extensive shrimp aquaculture has dramatically expanded in the coastal fringe of the Mekong Delta. This occurred primarily at the expense of the mangrove, already severely affected by the American war. More recently, paddy land has been reclaimed for shrimp aquaculture, a higher currency earner. However, production collapses regularly occur and the overall yield has remained far below the expectations with such traditional farming. A number of parameters come into play in the success of this activity, summarized in two questions: i) is the Mekong deltaïc environment, under high continental pressure, suitable to shrimp farming, ii) if not, is it still possible to adapt the simple rearing techniques of rural poor farmers to reach economic sustainability?

The Gambas project, under the aegis of the European Commission, is meant to answer these questions. This paper is based on the analysis of two full sets of data. Ecological data are composed of hydrobiological, hydrodynamic and land cover data. The former were collected at a number of stations encompassing the local variability, the latter were derived from processing Spot imagery. Besides, surveys of zootechniques and farm management were conducted with farmers' interviews over a network of shrimp farms, with the objective of determining the part played by these data in farming efficiency, with respect to the environmental conditions. Statistical methods, i.e. PCA for continuous variables and MCA (Multiple Correspondence Analysis) for qualitative ones respectively provided a zonation of the stations and a classification of the farms. GIS illustrated the distribution of the latter within the former. Summarizing yields per ecological zone revealed a production pattern that might lead to review and improve present land use planning policy and in particular the widespread integrated mangrove-shrimp system, a design fostered over the last decade. The results also showed that if management practises might be adapted to make up for adverse environmental conditions and reach a steady and homogeneous yield, this would be at a cost seldom bearable by local farmers.