Can Sediment Removal During Shrimp Production in the Wet Season Improve Pond Conditions of the Improved Extensive Shrimp System in the Mekong Delta, Vietnam?

Removing accumulated shrimp pond sediment is one of the most common management practices in shrimp aquaculture. In the Mekong Delta of Vietnam, the improved extensive shrimp farmers remove pond sediment when they observe abnormalities in their ponds (e.g. shrimp mortality, excessive algal development, foul smell, or too much turbidity). This on-farm study examines whether removing pond sediment in the wet season during shrimp production improves pond conditions. Sampling took place twice during shrimp production in six experimental ponds (bottom sediment was manually removed after the first sampling) and three control ponds (bottom sediment remained undisturbed). Results showed that sediment removal did not improve pond water conditions. The organic loadings of the pond bottom remained unchanged while macrozoobenthos density, species richness, diversity and evenness of the aquatic community were not affected. Only a small increase in redox potential of the pond sediment (p 0.01) was recorded. It is strongly recommended that farmers do not remove pond sediment in the improved extensive shrimp system under the defined conditions.