IMPACT OF STOCKING DENSITY ON SEDIMENT ACCUMULATION IN WHITELEG SHRIMP PONDS

Abstract

This study assessed the impact of stocking density on the process of sediment accumulation in whiteleg shrimp (Litopenaeus vannamei) ponds in Ninh Binh. Three farming models were compared: super-intensive A (219 shrimp/m²), B (167 shrimp/m²) and intensive C (92 shrimp/m²) over a 103 - day cycle. Sediment was collected periodically using specialized traps across four culture stages, from month 1 to month 4 (TN1 - TN4). The results showed that the amount of sediment gradually increased over time, peaking at TN3 with values of 74.56 ± 3.47 g/trap (model A), 70.18 ± 4.21 g/trap (B), and 57.37 ± 3.51 g/trap (C). The sediment amount then stabilized at TN4. The total accumulated sediment was highest in model A (175 ± 5.5 tons/ha/cycle), followed by B (161 ± 7.4 tons/ha/cycle) and lowest in C (131 ± 6.5 tons/ha/cycle). The average sedimentation rate was also highest in model A (255.93 ± 11.56 g/m²/day at TN4), compared to B (231.59 ± 18.73 g/m²/day) and C (194.11 ± 16.69 g/m²/day). Statistical analysis using the Friedman test (p < 0.001) confirmed a significant difference between the farming models, with model A consistently showing the highest sediment accumulation. The Spearman correlation coefficient (ρ > 0.86) indicated a strong positive relationship between farming duration and accumulated sediment. The study concludes that high stocking density significantly increases the amount of sediment, threatening environmental quality. Therefore, strict feed management, enhanced pond bottom siphoning and controlled stocking density are necessary to mitigate sediment pollution, especially in super-intensive models.