Water Budgets for a Rice–Crawfish Aquaculture System

Abstract Red swamp crawfish Procambarus clarkii and white river crawfish P. zonangulus are raised mostly in southern Louisiana, usually in association with commercial rice cultivation. Shallow ponds (fields) are flooded in the fall after the rice harvest (usually in October) and drained at the end of the crawfish production cycle the following spring–summer (usually in May–July). The water use and effluent volume associated with crawfish aquaculture have not been quantified. This study was conducted to determine water use and effluent release in crawfish aquaculture under simulated commercial conditions. Water inflow and outflow were measured in experimental crawfish ponds from 1999 to 2002 (three consecutive crawfish production seasons) that simulated rice–crawfish rotational production practices. The mean water inflow from groundwater pumping and precipitation was 228 cm per production season (range, 223–233 cm). Total water use (groundwater plus precipitation) and groundwater consumption averaged 21.5 and 15.2 m3 per kilogram of crawfish harvested, respectively. The amount of groundwater used for filling ponds, replacing losses from evaporation–evapotranspiration and seepage, and flushing ponds to maintain satisfactory dissolved oxygen levels averaged 139 cm (range, 97–165 cm). The contribution from precipitation averaged 90 cm. Effluent discharge averaged 59.5 cm. Of this, 36.9% was accounted for by pond drainage at the end of the production season, 29.4% by precipitation overflow and temporary levee failures, 22.1% by lateral seepage and minor leaks of the perimeter levees, and 11.6% by intentional flushing to maintain an acceptable concentration of dissolved oxygen. On average, 74% (172.5 cm) of the water input was lost as a result of evaporation, evapotranspiration, and percolation through the pond-bottom sediments.