Abstract
Penaeus monodon was one of the three main cultured prawns in the world, which had the characteristics of fast growth, large individual, strong disease resistance, a wide range of temperature and salt, delicious meat, and high market price. Guangdong, Fujian, Hainan, and other places were the main areas for rearing and breeding of Penaeus monodon in China, and the traditional extensive production method was its main production method. As the model’s shortcomings continue to emerge, this water and soil resource-dependent and ecologically destructive production method had become one of the major problems that restricted the sustainable development of Penaeus monodon. Circulating the aquaculture system was the current development direction of advanced aquaculture productivity, but so far there were still few reports on pond aquaculture and related research. In order to explore the feasibility and application development value of Penaeus monodon recirculating aquaculture, two sets of recirculating aquaculture systems composed of a pond, a protein separation unit, an inner circulating fluidized bed, and a circulating pump were designed and constructed in Rudong Base of Institute of Fishery Machinery and Instrument, Chinese Academy of Fishery Sciences in 2019, and the aquaculture experiments were carried out. The whole process of aeration aerator in the pond was started, and the whole process of water truck aerator in the later stage was running. The water circulation treatment system operated in the middle and late stages of aquaculture, and the circulation capacity was 26.50 m3/h (middle stage) and 33.00 m3/h (late stage). The amount of sewage discharged was 4%-10% (middle stage) and 10%-12% (later stage) of the aquaculture water body. In this paper, the key equipment was designed in detail and the circulating capacity was calculated, and the water quality condition, the growth of Penaeus monodon culture, the water purification function of protein separation combined device, internal circulating fluidized bed, and other equipment under the corresponding control mode in different culture stages were studied. Finally, the economy of culture operation was comprehensively analyzed. The results showed that the system operated smoothly for 120 days. During the culturing period, dissolved oxygen concentration was 5.30-7.14 mg/L, the pH value was 7.23-8.44, ammonia nitrogen concentration was 0.43-1.38 mg/L (after stable operation), nitrite nitrogen concentration was 0.15-0.56 mg/L(after stable operation). The results indicated that the removal load of suspended solids was (43.19±7.25) g/m3•h, the removal rate of ammonia nitrogen was (9.95±1.90)%, the dissolved oxygen was (9.45±0.87)%, the removal load of ammonia nitrogen was (122.34±22.56)g/m3•d, and the nitrification ability was better in the later stage than in the middle stage. The Penaeus monodon grew normally in the aquatic ecological environment of recirculating aquaculture mode and went through a rapid growth period, a stable growth period, and a slow growth period successively. The final culture density was 3.02 kg/m2, and the high-efficiency culture result was achieved. The final feed coefficient was 1.67, and the income per square meter of a single crop was 211.40 yuan according to the sales price of 70 yuan/kg. After deducting the cost, the profit per square meter per stubble was 34.78 yuan, the annual profit per square meter was 69.56 yuan based on two crops per year, which had achieved good economic benefits. The results show that the Penaeus monodon circulating aquaculture system offers a water quality control method for its growth characteristics and water environment requirements at different stages, realizes scientific feeding, and provides technical support for the application of the Penaeus monodon circulating aquaculture model.
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