A Comparison Study on Production and Plankton between Two Water Exchange Rates of Recirculating Shrimp Culture (Penaeus monodon) System Using Low Salinity Water

Abstract

     A  recirculating shrimp culture system was studied at a commercial shrimp farm in Thailand. Low salinity water was used for supply in the farm. Four experimental ponds were employed. Postlarvae 15 (PL 15) were stocked at a density of 44 PL/m². After 60 days of culture, two water exchange rates (i.e. 10% of pond water volume, once and twice a week) were tested. The system production from low percentage water exchange rate was 824±96.2 kg/rai, average weight of 20.9±1.84 g, The production from high percentage water exchange rate was 876±46.0 kg/rai, average weight of 23.4±2.33 g, growth rate of 0.17±0.05 g, survival rate of 56.4±1.2 % and FCR of 1.55±0.06. growth rate of 0.15±0.064 g/day, survival rate of 56.3±1.6 % and FCR of 1.55±0.06. However, there was not a statistically significant difference. Most water quality parameters were in an acceptable range. A large number of blue-green algae were often found during the culture period. Results show that the water exchange rate 10% once a week could obtain acceptable production results, which was not a statistically significant difference from the other rate. Therefore shrimp culture in recirculating systems using low salinity water with water exchange starting 60 days after culture, using 10% of pond water volume every week, was found acceptable.