Environmental performance of the mangrove-aquaculture farming system in the buffer zone of Ca Mau National Park, Ca Mau Province, Vietnam

In response to the rapid destruction of mangrove forestry for shrimp culture during 1980-1995 in Ca Mau Province of Vietnam, several policies and regulations have been issued and implemented by the Vietnamese government to reforest and protect the mangroves. The integrated mangrove-shrimp farming system which is carried out in the buffer zone of CA National Park (Decision No. 64/QD-UB), was promoted by the government to ensure both mangrove conservation and income generation. The system was designed based on area but this resulted to several technical and socio-economic problems such as mangrove destruction and human migration. This study was designed to assess the status of mangrove-shrimp farming system with different scales of mangrove area and shrimp pond area (Type 1 less than 3 ha:60 percent mangrove, 40 percent shrimp pond; and Type 2 greater than 3 ha:70 percent mangrove 30 percent shrimp pond). Household data were obtained through a random survey and water quality data were measured at the shrimp ponds. There were no significant differences in socio-demographic characteristics such as educational attainment, household size, age, and farming experience between the two types of farming system. Household size, highest education attainment, farming experience, age of respondents had no relationship with farm production and profitability, pH, salinity, temperature, EC, TSS, DO, COD, NH4+ of water did not significantly vary among the two farming systems. However, these factors had no relationship to shrimp yields. The mangrove forest area had no correlation with shrimp production. There were significant differences between the average density stocking and the stocking frequency of the two farming systems (P less than 0.05). The average productivity of Type 1 and Type 2 was 314.12 plus or minus 42.161 kg/ha/yr and 263.56 plus or minus 38.255 kg/ha/yr. Shrimp stocking frequency cost of production were positively correlated with shrimp production. The density of shrimp per month was negatively correlated with shrimp production (R2=0.563). The cost of production of Type 1 was higher than those of Type 2 farming while the average net profit per hectare of Type 1 was lower than those of Type 2 farming. There was significant difference about average net profit between the two types of farming systems (P less than 0.05). The implications of the integrated mangrove-shrimp farming system on its sustainability are discussed and appropriate recommendations are suggested.