The Effect of Stocking Density of The Western White Shrimp (Litopenaeus vannamei) Post Larvaes on The Growth Performance and Survival Rate inShrimpPonds of Gowater Site

This study has been conducted to determine the effect of Postlarva of Litopenaeus vannamei stocking density on growth and survival index and was carried out in 9 ponds (one hectar) from April to August 2011 in a field belonging to 647 Ata corporation in Gowater Site in Chabahar. After pond prepartion, postlarvaes at PL15 in three different densities of 15, 20 and 25 square meter (labeld treatment 1,2,3 respectivly) with three replicates for each one have been stored. Physical and chemical factors of water such as tempreture, oxygen, pH twice daily (morning and evening) and also salinity and transparency have been measured once a day. Feeding of postlarva during culture period based on requirements in different age and weight, levels and in different environmental conditions was performed using Internal food concentrates. biometric practices of shrimps by way of cast net and feeding trays once every ten days have been calculated and recorded. Culture management practices were similar for all ponds. The results of the effect of density in 115 days rearing on growth indices between treatments 1 and 2 and 3 of the final product and the mean weight, showed significant differences in all three treatments at 95% confidence level (P<%5), Also in terms of survival rate treatments 1 and 2 showed significant diffrences in comparison with treatment 3 (P<%5). The overall Results of mean weight at 115 days growing in treatment 1 and 135 days growing in treatments 2 and 3, respectively, 17.93 ±. 23 and 16.68 ±. 07 and 15.64 ±. 12 g and the final production order of, 2460± 78.1, 3033 ± 76.38, 3200 ± 50 kg and average daily growth were. 18 ±. 002,. 14 ±. 002,. 13 ±. 001 g per day, respectively. Also the highest survival rate and the lowest feed conversion ratio that were 91.44 ± 1.72 and 1.3 ±. 06 which belonged to treatment 1 and the lowest survival rate and highest feed conversion ratio were respectively 81.86 ±. 78 and 1.57 ±. 03 which belonged to treatment 3 is obtained. The results of economic surreys at different densities showed that the highest mean weight of treatment 1 and the lowest feed conversion, were economically better than other treatments. Also with Increasing the stocking density, economic profit decreased.