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This study was conducted in order to characterize the effects of different diets on survival and some growth factors of Acipenser persicus in the International Sturgeon Research Institute in 2010. Thirty tanks were prepared and filled with water. Also, 60 larvae were selected randomly and their weight and length were measured and then were transferred to mentioned tanks. Ten diets containing different amounts of usual concentrated feed, Daphnia powder and Nereis powder were prepared as experimental diets. Five days after active feeding, in order to adaptation with larvae digestive system, feeding with special diets was continued. Ten days after active feeding, larvae were fed 30% of their wet weight with experimental diets for 35 days. Physico-chemical parameters of water were measured carefully twice a day. At the end of experiment, the weight and the length of larvae were measured and survival rate and some growth factors such as FCR, SGR, BWI and GR were calculated. The results showed that larvae fed diet 3 (100% Nereis powder) and diet 4 (50% Daphnia powder and 50% Nereis powder) had the highest survival rate, SGR, BWI and GR compared to other treatments (p<0.05). On the other hand, these two treatments (3 and 4) along with treatments 1 and 5 have the lowest FCR compared to other treatments (p<0.05). The lowest survival rate, SGR, BWI and GR was observed in fish fed diets containing 100% concentrated feed (p<0.05). The results of the present study showed that using Nereis powder lonely or in combination with Daphnia powder comparing to concentrated feed may have beneficial effects on survival and growth of Acipenser persicus.

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This study was carried out during the artificial propagation season in the shahid beheshti Sturgeon Rearing and Propagation Center and International STURGEON Research Institute (Rasht) during 2009. Eleven wild male Acipenser Persicus brood fish were used for this study. Each brood fish was stripped after receiving hormone injection and then sperm samples were examined separately. Fertilization rate and hatching rate of larvae were also determined. Analysis of relationship between sperm pHand density and indices of reproduction showed positive and direct relationship between hatching rate and sperm pH (p<0.05, r=0.711), as well as between sperm pH and fertilization rate (p<0.05, r=0.633). However egative relationship was opserved between sperm density and fertilization rate(p<0.05, r=0.640) and between sperm density and hatching rate (p<0.05, r=0.745).

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In fish hatcheries, disinfectants are usually used for controlling the infections of body surfaces of the fish and to prevent or eradicate the pathogenic organisms. Copper sulphate (CuSO4, 5H2O) and potassium permanganate (KMnO4) are among the important disinfectants which used in aquaculture facilities. In the present study an attempt was made to determine LC50 in 96 h of these two disinfectants and to study their effects on gills and liver tissues of Acipenserpersicus fry in vitro. Persian sturgeon fingerlings with mean weight of 1.57±0.2 mg were maintained in a static system for 96 hours at a water temperature of 23.7±0.38 ºC, dissolved oxygen concentration of 7.08±0.2 mg/l and a pH of 8.25±0.06. Total hardness of the water was determined as 330 mg/l. Gills and liver tissue of A. persicus fry were examined for microscopic and histopathologcal alterations after 96 h. LC50 in 96 h was determined as 0.15 mg/l and 0.41 mg/l, for CuSO4,5H2O and KMnO4 respectively. Results of histology study showed many lesion including, hyperplasia, secondary lamellae adhesion, thickening of supporting cartilage in gill filaments, elongation of secondary filaments, edema of the lamellae, hyper secretion of mucous in gills, cell atrophy, cell necrosis, cell degeneration of the hepatocytes and intravascular haemolysis in blood vessel of liver. We can conclude that inappropriate use of these disinfectants may result in toxicity of fish and also causes structural changes in fish tissues.

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In order to evaluating of herbicide Butachlor sublethal effects on Acipenser persicus fingerlings acute toxicity examination was carried out statistically using OECD standard method in the International Sturgeon Research Institute (Rasht-Iran). A total of 120 fish (with mean weight 10 ± 2 gr) were exposed to different concentrations including 0 (control), 0.107, 0.215 and 0.322 mg/L of butachlor. Mean lethal concentration of butachlor (LC50 96h) determined 0.43 mg/L during 96 hours. Blood samples were collected from caudal vein after 24 and 96 hours for biochemical studies. The study for determining sublethal effects of butachlor on liver tissue of Persian sturgeon carried out in laboratory conditions. Results showed that cortisol and glucose levels increased significantly (P<0.05) in different concentrations compared to control. The histological study of liver tissues of the experimental fish with the control groups showed clear changes including congestion, hemorrhage, cytoplasm vacuolation and pycnosis of nucleus, the cumulative haemosiderin in the melanomacrophage cells and also necrosis and acidophilic changes of the cells. Results indicated that butachlor at low level induced abnormal effects on biophysiological structure of Acipenser persicus fingerlings.

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A considerable amount of Persian sturgeon fingerlings has been cultured in hatcheries and releases into the Sea annually. High density of these fish in hatcheries and the importance of keeping their health for facing new environment and salinity conditions is a key to understanding the parasitology and pathologic studies. 100 number of 2-3g Persian sturgeon fingerlings were obtained from sturgeon hatchery. Based on histological observation of the gill, the unicellular parasite, Trichodina of Trichodinidae has been recognized. This parasite was observed in gill chamber, spiracle, buccal and pharyngeal chambers of the fingerlings. 15% of studied fish were contaminated to this parasite. Gill damaged by this parasite was especially to the capillaries by bleeding and clot making. Also due to the attachment of this parasite to gill lamellae and the tissue damages of the gill it could be interfere with respiration and osmoregulation of the infected fish.

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This research was carried out to compare the effect of methionine as a synthetic attractant and farmed Chironomid extract as a natural attractant on growth and carcass composition of Persian sturgeon (Acipenser persicus) larvae. A total number of 240 larvae weighing 0.4±0.09 g and total length 3.8±0.29 cm were fed under rearing conditions in International Sturgeon Research Institute for 8 weeks. Four treatments were designed including control (without attractant), farmed Chironomid extracts at the levels of 5% and 25% and methionine 3% in three replicates (completely randomized design). Larvae were randomly distributed into twelve 30-L fiberglass tanks equipped with aeration system. The results showed that the final weight, percentage of body weight increase, specific growth rate, final biomass, protein efficiency ratio and survival rate in 25% farmed Chironomid extract were significantly higher than the other treatments (P<0.05). In addition, farmed Chironomid extract at the level of 25% had the lowest FCR which showed significant difference with other experimental treatments (P<0.05). There were no significant differences in carcass composition including protein, fat and moisture percentage in among the treatments (P>0.05). Based on findings, farmed Chironomid extract at the level of 25% can stimulate the appetite of Persian sturgeon larvae and improve the growth parameters.