Production of freshwater prawn; Macrobrachium rosenbergii (de man); in southern Brazilian ponds; under different initial weight and densities

Abstract

The production of freshwater prawns was examined under semi-intensive growth conditions in ponds of five locations in the States of Rio Grande do Sul and the south region of Santa Catarina, southern Brazil, in the summer of 87/88. Post-larvae (0.013 g average) and nursed juveniles (0.800 g average) were stocked in different size ponds at densities of 8/m², 10/m², 12/m², 17/m², 22/m² (post-larvae) and 6/m², 8/m² (juveniles). All ponds had a water exchange rate of 5-10% of the volume/day. Water quality was evaluated every two weeks by measuring ammonia, pH and dissolved oxygen and, twice a day, by temperature and transparence. Feeding was uniform in all locations at the rate of 5% estimated biomass/day, and the pellets had 30% crude protein. It was found after five months of grow-out of post-larvae, a yield of 550-1,150 kg/ha and the nursed juvenile population yielded 755-985 kg/ha. It was found relation between stocking density and yield. Since the grow-out period in the region takes six to seven months, and more advanced procedures can be applied, it appears to be possible to yield 1,500 to 2,000 kg/ha within the grow-out period by improving management. The findings of this study call for more intensive efforts in researching this aquatic species in subtropical south of Brazil.