Effects of water exchange protocols on water quality, sedimentation rate and production performance of P enaeus monodon in earthen ponds

This study was carried out in farmers' fields to quantify the total water and consumptive water use in grow‐out culture of P enaeus monodon under recommended package of practice with two different water management protocols: T 1 , with no water exchange and T 2 , with regulated water exchange. Treatment‐wise estimated total water use, was 2.09 and 2.43 ha‐m 122 day −1 , while the computed consumptive water use index (m 3  kg −1 biomass) was 5.35 and 6.02 in T 1 and T 2 respectively. Lower rates of water exchange (T 2 ) showed significantly improved ( P  < 0.05) crop performance in terms of performance index (19.75 ± 0.75), production‐size index (74.1 ± 3.4), survival rate (80.13 ± 1.7%) and productivity (2.44 ± 0.08 t) over the zero water exchange. The shrimp pond water quality suitability index ( WQSI ) infers that regulated water exchange (T 2 ) improved the overall suitability of water quality for shrimp culture. WQSI up to 90 days of culture ranged between 7.5–9.0 in T 2 , needs little management while in the last month of rearing, it was good with moderate management requirements. Treatment‐wise sediment load ranged between 50.4–56.3 m 3  t −1 shrimp biomass. High intensity of water exchange and low apparent feed conversion ratio influenced in lowering the sedimentation rate. Regulated water exchange protocol (T 2 ) performed well (higher net total water productivity and net consumptive water productivity) against no water exchange (T 1 ). A higher OV : CC ratio (ratio of the output value to the cost of cultivation) indicated that T 2 had a distinct edge over the T 1 protocol.