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CoastGIS03 - Genova – Oct. 16-18, 2003 GIS in support to data analysis for enhanced sustainability of shrimp farming in the Mekong Delta, Vietnam The Gambas.

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Presentation on theme: "CoastGIS03 - Genova – Oct. 16-18, 2003 GIS in support to data analysis for enhanced sustainability of shrimp farming in the Mekong Delta, Vietnam The Gambas."— Presentation transcript:

1 CoastGIS03 - Genova – Oct , 2003 GIS in support to data analysis for enhanced sustainability of shrimp farming in the Mekong Delta, Vietnam The Gambas project Jacques Populus*, Raweewan Nutpramoon**, Jean-Louis Martin***, Pascal Raux****, Yves Auda*****, Hoang Son****** * Ifremer, DEL/AO, Centre de Brest, Plouzané, France ** GISTDA, Bangkok, Thailand, *** Crema, France ****CEDEM-UBO, Brest, **** CESBIO, Toulouse, France* **** Institute of Oceanography, Nha Trang, Vietnam

2 CoastGIS03 - Genova – Oct , 2003 Gambas Extensive Mekong delta aquaculture Mekong delta ha ponds households tons ha mangrove left

3 CoastGIS03 - Genova – Oct , 2003 Gambas How about sustainability? Technical sustainability Economical sustainability Social equity Efficiency : Average yield in Ca Mau province YearAverage yield (kg. ha -1 )

4 CoastGIS03 - Genova – Oct , 2003 Gambas Factors contributing to sustainability

5 CoastGIS03 - Genova – Oct , 2003 Gambas Location of study sites

6 CoastGIS03 - Genova – Oct , 2003 Gambas Stations in Tra Vinh site

7 CoastGIS03 - Genova – Oct , 2003 Gambas Data collected Land use : soils, vegetation, biodiversity (31 stations) Hydrobiology: water and sediment (22 variables) Hydraulic: tide, water levels (Camau only) Practise and socio-economics (Survey of 160 farms)

8 CoastGIS03 - Genova – Oct , 2003 Gambas Processing Spot imagery for land use mapping Five ecological zones are identified I : paddy, orchards, households II : mixture of shrimp ponds and mangrove III : dominant mangrove IV : natural shoreline mangrove V : shoreline sandy ridges Spot 4 image January 22nd, 2001

9 CoastGIS03 - Genova – Oct , 2003 Gambas Processing Spot imagery for land use mapping Spot 4 image January 22nd, 2001

10 CoastGIS03 - Genova – Oct , 2003 Gambas Analysis 1: yield versus mangrove Percentage of mangrove within 2 km around stations Total yield per ha per year

11 CoastGIS03 - Genova – Oct , 2003 Gambas Analysis 1: yield versus mangrove the general value of « natural » mangrove is universally recognised however the value of mangrove replanted in ponds is questioned (shadows, sudden salinity drops, tannins) Therefore, the « separate » sytem should gradually replace the mixed system Clough, 2002

12 CoastGIS03 - Genova – Oct , 2003 Gambas Analysis 2: PCA on water quality Two clusters: particulate (TSS) and primary production Salinity : inversely correlated to TSS group (dominance of rainy season) Stations clustered in seven groups according to PCA Definition of key variables (indicators)

13 CoastGIS03 - Genova – Oct , 2003 Gambas Analysis 2: hydrobiological zonation Each zone qualified by its most striking features TSS Bacteria Organic matter (OM) Detritic organic matter rules the system

14 CoastGIS03 - Genova – Oct , 2003 Gambas Analysis 2: organic matter in sediment Higher TSS in Camau, even in dry season, leading to accumulation of detritic OM

15 CoastGIS03 - Genova – Oct , 2003 Aver.Yield per crop Profit rate Gambas Analysis 3: farm classification (global)

16 CoastGIS03 - Genova – Oct , 2003 Gambas Analysis 3: farm classification per ecological zone Postulate - The hydrobiological zones are homogeneous - Discrepancies in yields are explained by management Either farm structure parametersEither farm structure parameters Or Crop practice parametersOr Crop practice parameters

17 CoastGIS03 - Genova – Oct , 2003 Gambas Analysis 3: farm classification per ecological zone Zone 6, Tra Vinh Low TSS Level environment is the key factor for successful cropsenvironment is the key factor for successful crops yet, most thorough pond preparation and monitoring arefound hereyet, most thorough pond preparation and monitoring arefound here farmers ought to remain at reasonable intensification levelfarmers ought to remain at reasonable intensification level (4 to 6 PL/ (i.e. 10 PL/m²) water "top up" seems to be the most efficient techniquewater "top up" seems to be the most efficient technique

18 CoastGIS03 - Genova – Oct , 2003 Gambas Analysis 3: farm classification per ecological zone Zone 4, Ca Mau High DON Recommendations in Ca Mau High DON: Reduce crop numberReduce crop number Stoking Density < 2 PL/m²Stoking Density < 2 PL/m² Avoid chemical and artificial feedAvoid chemical and artificial feed Target null energy cost (feeding) by relying on environmental capacityTarget null energy cost (feeding) by relying on environmental capacity

19 CoastGIS03 - Genova – Oct , 2003 Gambas Analysis 3: farm classification per ecological zone Zone 3, Ca Mau core

20 CoastGIS03 - Genova – Oct , 2003 Gambas Analysis 3: farm classification per ecological zone distribution of practises similar among worst and best farmsdistribution of practises similar among worst and best farms from a technical point view, all semi-extensive farms belong to the worst farmsfrom a technical point view, all semi-extensive farms belong to the worst farms Remain at low intensification level (2PL/m²)Remain at low intensification level (2PL/m²) No feed supplyNo feed supply Further look at post-larvae qualityFurther look at post-larvae quality Zone 3, Ca Mau core Precautionary approach:

21 CoastGIS03 - Genova – Oct , 2003 Gambas Conclusions 1 The environment is adverse, due to high organic load, reduced primary production and reduced trophic chain development Intensification is NOT sustainable: collapses appear rapidely, unless stocking densities are kept low the key question is how, NOT how much to produce (low risk to households) Re-design of farm layout necessary,with regard to mangrove, tending to organic farming Some sub-areas may allow semi-intensive conditions (SD<6), but costs are to be kept low The study allowed the creation of a corpus of data on Mekong aquaculture Key eclogical indicators for monitoring/selecting sites can be proposed

22 CoastGIS03 - Genova – Oct , 2003 Gambas Conclusions 2 The study allowed the creation of a corpus of data on Mekong aquaculture and environment Key eclogical indicators for monitoring/selecting sites can be proposed Salinity/pH TSS Total OM DBO Vibrio


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