Benefits of Male Monosex Culture of Giant Freshwater Prawn (Macrobrachium rosenbergii): Improving Growth Performance, Production Yield, and Profitability

Abstract

We evaluated the advantages of all-male giant freshwater prawn (Macrobrachium rosenbergii) culture over traditional mixed-sex and all-female systems in the aspects of growth performance, production yield, and profitability. The prawn post-larvae were reared in a nursery pond for 43 days until the male sexual characteristics (gonopore complex) could be distinguished externally, then they were sexed and transferred to monosex grow-out ponds (two ponds per sex) and cultured for another 140 days. The prawn post-larvae in the mixed-sex group were reared for 60 days in the nursery phase and 165 days in the grow-out phase. At harvest, the male prawns from the all-male group had higher body weight (93.02 g), average daily growth (0.66 g·day^-1), and specific growth rate (3.41%·day^-1), compared to the males in the mixed-sex system (69.38 g, 0.41 g·day^-1, and 2.56%·day^-1, respectively). The proportion of an unfavorable “small male” morphotype was reduced from 20.11 % in the mixed-sex culture to 4.67 % in the all-male system, whereas that of a desirable “orange claw” morphotype was increased from 38.59 to 61.33 %. Ultimately, the production yield of the all-male group was 2,076.6 kg·ha^-1, whereas that of the mixed-sex system was 1,273.8 kg·ha^-1. The cost-benefit analysis revealed that the former was 155.78 % more profitable than the latter. The all-female group showed the best survival rate and feed conversion ratio, yet it was the least profitable system. In conclusion, the all-male culture was the most productive and profitable system of giant freshwater prawn farming.