Effects of Harvesting Methods on Population Structure, Growth and Yield of Freshwater Prawn,Macrobrachium rosenbergii, Cultured at Two Densities

Effects of harvesting methods (cull and batch) on population structure, growth, and yield of freshwater prawn, Macrobrachiurn rosenbergii, cultured at two densities (5/m2 and 10/m2) were evaluated. Females (67.4%) were more abundant than males (32.6%), but there was no effect of harvesting methods and stocking rates on sex ratio (P > 0.05). Mean survival rates ranged from 78.3 to 92.6%, being highest at a stocking density of 10/m2 and cull-harvested (P < 0.05), but were not different (P > 0.05) among three other treatments. After 196 days of culture, mean weights ranged from 25.3 to 29.9 g and were not significantly different from each other (P > 0.05). Mean weight of males was not hi her than that of f females (P > 0.05), except in one treatment (5/m2 , batch harvest) where males were heavier (P < 0.05). Maximum specific growth rate (SGR) was recorded for prawns cultured at a density of 5/m2 and cull-harvested (0.66%/day), followed by prawns at 10/m2 and cull-harvested (0.58%/day). Minimum SGR was found for prawns cultured at 10/m2 density and balch-harvested (0.43%/day). Maximum yield (2366 kg/ha and 2099 kg/ha) was recorded at the higher density (P < 0.05). Harvesting method had no effect on yield at any density (P > 0.05).