Evaluation of stocking density vannamei shrimp Litopenaeus vannamei (Boone, 1931) in culturing with brackish water of Caspian Sea

Recently, the development of aquaculture has focused on the use of seawater, because of freshwater crisis in the world. Whiteleg shrimp (Litopenaeus vannamei) is one of the most important species for aquaculture development, because of tolerance and adaptation to different ecological conditions. One of the advantages of species in aquaculture, compatibility status is dense in the rearing period. In this study, the effect of different densities (45/m^2 , 50/m^2 , 55/m^2 and 60/m^2 ), of primary stock whiteleg shrimp postlarvae (PL12) on the growth and survival rate were evaluated. Brackish water (10.52±0.43 ppt) was providing from Caspian Sea. The experiments were performed in 12 circular concrete pond with a sandy bed (area: 78m^2 ) in four treatments and three replications for each treatment. The experiments performed in a 75-day period. In this study, the water temperature was 27.4±1.79°C. The results showed statistically difference in growth parameters and survival rate among experimental treatments (Duncan test, P<0.05). Therefore, with high levels of density, has decreased the amount of weight gain and survival rate (SR), specific growth rate (SGR) and average daily growth (ADG). In addition, the treatments were different variations of FCR (P<0.05) and not depend on the primary stock density of postlarvae. In low density (45/m^2 ) were observed the highest growth (SGR=11±0.04 and ADG=0.25±0.01 gr/day/ind.), survival rate and calculate the amount of production per 78m2 equal 43.6±3.3kg (5596±433kg/ha). Therefore, It is possibility that there is commonly increasing primary stocking of density about L. vannamei postlarvae culture in Iran

Limnologic study Sabalan run off Dam for aquaculture fish cold water

Limnological study of Sabalan run off Damfor aquaculture cold water fish was conducted in sixtimesat four stations from July to December 2009. Average minimum and maximum parameters measured in different stations were included water temperature, dissolved Oxygen, total hardness, electrical conductivity, pH, BOD5, COD, TDS, NH4, NO2, NO3, PO4, TN, TP, SiO2, respectively (10/3±9/5-14±8/7°C), (9±1/2-11/4±2/1 mg/liter), (367±19/8-381±17/8mg/liter), (0/95±0/07-1/05±0/07 mz/cm), (8/3±0/1-8/4±0/1), (3/3±1/14-3/88 ± 0/71mg/ liter), (15/5 ± 3/1-16/3 ± 3 mg/liter), (0/48 ± 0/04-0/54 ± 0/06mg/ liter), (0/08 ± 0/02-0/13 ± 0/07 mg/liter), (0/004 ± 0/003- 0/05 ± 0/1 mg/ liter), (0/6 ± 0/2-0/64 ± 0/29 mg/ liter), (0/19 ± 0/07-0/22 ± 0/07 mg/ liter), (10/48 ± 0/6-10/98 ± 0/54mg/liter), (0/39 ± 0/11-0/44 ± 0/18 mg/liter), and(9/9 ±0/6-11/1 ± 1/4 mg/liter). Average minimum and maximum of water heavy metalswas included of Cd, Pb, Zn, Fe, Cuand Ni respectively was measured as ND(No Deliver), ND, ND- 0/242, ND- 1/075, ND- 0/018 and ND-0/014inmg/ liter. Also among the 16 organochlorinecom pounds measured the highest amount of was belonged totoxin Hexachlorine Benzene (1/5 mg/ liter). The results of the analysis of water quality parameters showed that parameters except ofCOD, TDS, PO4, TP, Zn, Fe and water temperature, other parameters do not haveany restrictions foraquaculturecold water fish in therunoffDam. Based on data results it was noticed that there was temperature restriction up to November at downstream and station 2 showed less temperature fluctuation and more suitable condition compared to other stations. BOD5 value was within the allowable range for growing trout, in which station 2 somewhat with lower volatility of value had the most suitable BOD5 condition. In the present study, the amount of TDS in the study area was somewhat higher than the limitation and since TDS values increased with distance from the dam, therefore station 2 had somewhat better conditions for fish farming. In addition the amount of EC in the study area, indicating the inappropriateness of it for various activities in the fisheries. Although none of the stations in terms of the amount of phosphorus didn't show favorable conditions for rainbow trout fish propagation, it appears between the researches stations, station 2 had the most favorable terms. The results of this study (regardless of the unseen), it seems that in August and September; Zn had overestimated value for cold fish propagation. Recent study showed that among heavy metals, Fe in water, sediments and fish was over limitation value. Also, Fe value was measured of 1.08 at station 4, which showed over normal value for cold fish propagation. Therefore, station 2 at downstream seemed to have suitable cold fish propagation due to lower Fe value. On the based on the recent study, planktonic biological index did not endorse water quality for fish propagation. In this study, aquatic plant such as Potamogeton pectinatus and Pheragmitie saustralis was found at water of higher and somehow polluted organic matter. Probably, based on the results it was noticed that downstream water of dam was polluted to organic matter. At the recent study, resisted maroinvertebrates to organic matter (Chironomidae) was consisted noticeable frequency compared to other sensitive invertebrates to organic matter (EPT).Statistically, it can be expressed that probably organic pollution resulted to increase of resistance invertebrates and decreased of sensitive groups. In recent study, EPT/CHIR index was measured 0.6 in station 2 and 1.74 in station 4. This ration was less to many other mountain rivers. As ETP sensitive invertebrates has higher sensitive to other groups with the regards of environmental condition and pollution, unpredicted increase of Chironomidae compare to sensitive groups resulted of EPT/CHIR value which showed environmental stress. In this study, HFBI index was measured as 7.49 at station 2 and 7 in station 4. Based on HFBI index, station 2 was classified as a high organic pollution and station 4 with noticeable organic pollution. At the recent study, station 2 was catch more fish to station4. For instance, Squaliuscephalus and Alburnoides pinctatus were catch in station 2 and were not found in station 4. As a whole, Biological indicators whichwas included Plankton Bioindicator, EPT / CHIR. ,Hilsenh off Biological Indicator, diversity and distribution ofaquatic plants and fish, showed water situation in run off Damrich inorganic matter. Finally, the study area was approved for fish farm about 50 tons and needs management arrangements with the increased production rate