Effects of various shrimp (Penaeus monodon) densities on their growth, water and sediment quality, and water budget

Abstract

The total water use (TWU) and consumptive water use index (CWUI) in monoculture of Penaeus monodon under varying intensity levels [T1: 150,000 post larvae (PL) ha−1, T2: 200,000 PL ha−1, T3: 250,000 PL ha−1] were quantified. Treatment-wise-estimated TWU was 2.98 × 104, 3.24 × 104, and 3.59 × 104 m3 ha−1 125d−1, while the CWUI was 5.12, 4.72, and 4.96 m3 kg−1 shrimp production in T1, T2, and T3, respectively. The estimated evaporation and seepage loss ranged between 1.2–1.7 and 1.1–1.5 m3 water kg−1 shrimp production, respectively, and contributed significantly to consumptive water use (CWU). Higher the stocking density, lower was the water quality suitability index (WQSI) as in T3 followed by T2 and T1. WQSI up to 75 days of culture rated very good, ranged between 7.5–9.0 in T1 and T2, while rest of the period it was good (5.5–7.5) with moderate management requirements. Treatment-wise sediment load ranged between 39.0 and 45.3 m3 t−1 shrimp biomass. Among the treatments, minimization of total water use (3.24 × 104, m3), CWU (2.16 × 104, m3) and water exchange (0.90 × 104, m3) at stocking density 20 post-larvae m−2 (T2), resulted in higher (p < 0.05) growth rate (30.45 g), yield (4.58 t ha−1), output value - cost of cultivation ratio (2.46) and net consumptive water productivity (USD 0.65 m−3). Findings of this study would help in preventing wasteful use of water and would address the management and operational issues in coastal shrimp aquaculture.