Compensatory growth of the white shrimp Litopenaeus vannamei (Boone, 1931) in the extreme south of Brazil
The present study evaluated the occurrence of compensatory growth of the white shrimp Litopenaeus vannamei submitted to a long period of nursery at a high stocking rate and exposed to low temperatures in late winter and early spring, in southern Brazil. Shrimps were bred in two different cultivation systems: the treatment called “compensatory growth” (CC) evaluated growth performance of shrimps kept in a nursery for 145 days, at a stocking density of 2000 shrimps/m² during the winter in a 20 m² tank without heating system; and the control treatment, here called “normal growth” (CN) where the shrimp were kept in an identical nursery tank, at the same density, but for a period of 16 days, in late spring, when the temperature increased.Survival and average weight after the nursery period was 79.7% and 0.64 & # 61617; 0.31g for CC treatment and 93.0% and 0.36 0.09g for CN treatment. The prawns were then transferred to four fattening ponds, coated with HDPE (two replicates per treatment) and bred for 101 days until harvest. During the fattening period, every 18 days, fifty individuals were collected randomly from each nursery and were weighed individually on a scale with an accuracy of 0.01g. In harvesting, the final biomass of each pond was recorded and 100 shrimp from each pond were individually weighed to determine the final weight and survival rate. Additionally, the specific growth rate (TEC),the weekly growth rate (TCS) and percentage of weekly growth (PCS) were calculated for each nursery. The collected data were submitted to statistical analysis of comparison of means (T-test). The results showed that the shrimp reared in the CC treatment reached a significantly higher final average weight (p <0.05) than the shrimp in the control treatment (NC). The TEC in the first biometry was significantly higher in the shrimp reared in the CC treatment, later the shrimp in the control treatment had a higher TEC. The results of the experiment clearly demonstrate that shrimps kept for a long time in the nursery, at high stocking densities and exposed to low temperatures showed compensatory growth during the beginning of the fattening period. The results can help to improve the management practices employed in shrimp production farms through better use of their facilities.