In this study the effects of LHRHa, a mixture of common carp and sturgeon pituitary extracts (CCP+SPE), Thyroxin hormone (T3) with commonly method used in hatcheries were compared. The experiments were conducted using different doses of hormones with several replicates in order to determine the most effective dose. Total number of brood stocks were 58 females and 22 males. Prior to injecting the fishes, the Germinal Vesicle (GV) situation of all broodstocks were determined. The results showed that broodstocks has been injected with LHRHa were very satisfactory and the percentage of response; fertilization and hatching of them had significantly different. The least effective dose of LHRHa that induced maturation was 250µg/fish for single injection and 350-375µg/fish for double injection. Thus it was determined that under the experimental conditions, 20.0 to 31.2 µg/Kg of body weight of brood stock was the most effective dose. In the case of male broodstocks LHRHa was the most effective hormone and the sperms collected from these broodstocks were better in quality and quantity.

Motility of spermatozoa was studied on 12 and 7 specimens of Acipenser persicus and A. STELLATUS, respectively. The density measured to be 2.22±0.65x109ml-1 in A. persicus and 2.21±0.55x109ml-1 in A. STELLATUS. Semen samples were diluted with two extenders containing tris 118mM, sucrose 23.4mM, pH=8, egg yolk (20%), dimethyl sulfoxide (15%) and penicillin potassium (500IU/ml) and biociphus extender containing glycerol as a cryoprotectant at a ratio of 1:1 and then transferred to 0.5ml straws and frozen in a computer controlled low temperature apparatus and stored in liquid nitrogen for one week. To study fertilizing ability, the spermatozoa were then used to inseminate eggs after thawing. Mean sperm motility in fresh spermatozoa was 86.6% in A. persicus and 73.75% in A. STELLATUS which decreased to 32.2% (P<0.001) and 37.5% (P<0.001) in frozen spermatozoa, respectively. Also mean fertilization rate decreased from 90.4% to 30.7% in A. persicus and from 72% to 36.8% in A. STELLATUS.

A new formulation of GnRH and synthetic compound of anti-dopamine domperidone was used for the first time in Iran to determine suitable physiological indexes for reproduction and to resolve the present problems of artificial reproduction in stellate sturgeon Acipenser STELLATUS. The study was conducted on 60 breeder Acipensers including 40 female and 20 male specimens. The fish were caught at stations in the vicinity of the SefidRud River in Guilan Province. Male spawners were treated using single injection method while females received dual injection (Bio-physiological control).Propylene glycole (PG) was administered after the muscular injection near the second dorsal scute to increase the viscosity of the solution during absorption. Depending on the stage of sexual maturity in the fish, GnRH at doses of 5, 10, 15, 20, 30 µg / kg BW was used in combination with a dose of 1 or 2 mg / kg of domperidone.The position of GV was used as an index to determine sexual maturity in females while in males sexual maturity was determined on the basis of testis and sperm quality. The female fish showed GV in a range of 3.64 to 14.30. The results indicated that reduction of stress during catch, transportation, maintenance and handling and selection of breeders with suitable morphology will result in increased reproduction success.It was also found that male breeders given a dose of 20 and 30 µg / kg BW GnRH along with 1 and 2 mg / kg of domperidone respectively were the most successful in spermiation. For female breeders, those received a dose of 10, 15 and 20 µg / kg BW GnRH along with 2 mg / kg of domperidone exhibited the most suitable conditions in ovulation. These females responded well to artificial breeding provided they possessed GV in the range of 3.64 to 14.30 depending on the water temperature until the germinal vesicle broke down (in vivo).Alleviating stress during capture, handling, transport and confinement, selecting breeders with suitable morphology and identifying correct stage of sexual maturity are the factors that help achieve higher production by substituting GnRH with a combination of GnRH and domperidone. Therefore, this compound is recommended as a suitable substitute for pituitary extract and other gonadotrophic analogues in the artificial breeding of Acipenser STELLATUS.

The sturgeon eggs, upon fertilization and contact with water develop stickiness due to glycoprotein molecules in jelly coat layer. In artificial breeding, egg adhesion is a main problem. So, various techniques have been developed to address this problem. Many of methods being time consuming and may cause damages to the eggs. In this study, Sodium hypochlorite (SH) at 0. 03% concentration for 40 s exposure time was tested on stellate sturgeon, Acipenser STELLATUS eggs and its effects was compared with other de-adhesion methods (Kaolin, tannic acid and clay). The lowest fungal and died eggs (31. 94 ± 3. 8%; P>0. 05) and highest hatching rate (68. 06 ± 5. 5%; P>0. 05) were observed at SH treatment. It was concluded that treatment with SH is a simple, inexpensive and rapid method for de-adhesion of sturgeon eggs.

The toxic effects of the herbicide Butachlor were studied using a concentration of 0.4- I.3ppm and 0/1-1ppm on fingerlings of the Persian sturgeon and STELLATUS sturgeon respectively in 1999. We carried out six treatments with three replicates and used one control based on the static O.E.C. D. method. Over the experiments, pH ranged between 6.7 -8.2, total hardness was measured to be 230 mg/l, water temperature was 20±1 degrees centigrade and dissolved oxygen was above 6 mg/l.We found that the LC50 96h of the Butachlor on fingerlings of the Persian sturgeon and STELLATUS sturgeon weighing 1-3 grams was 0.44 and 0.07 mg/l respectively. Also assessed the LC10,LC50,LC90 of the herbicide on the fingerlings of the sturgeons using the Probit Analysis procedure. We determined the maximum allowable concentration of the Butachlor herbicide for the fingerlings of the Persian and STELLATUS sturgeons to be 0.044 and 0.007 mg/I. Based on the standards, the herbicide is considered highly toxic for the studied fingerlings.

Abstrac:. A total of 1,200 A. STELLATUS juveniles at different ages of 55, 69, 77 and 85 days were stored at a density of 100 eggs per square meter. Habitation of A. STELLATUS juveniles in four breeding treatments including 55 days (0.5-1 g), 69 days (1-3 g), 77 days, (3-5 g) and 85 days (5-10 g) in water Accepted and 4 experiments in different salinities (0-- 0-5, 4-5 /., 9-4 and 9-13) and each experiment was designed in 4 treatments and each treatment had 3 replications. The results of the present study showed that the best breeding period for releasing juvenile A. STELLATUS fish into the sea (salinity 9-13) during 77 and 85 days (3 to 5 and 5 to 10 g) (df = 3, F = 8.933 P = 0.006) and (, df = 3, F = 68.800 P = 0.000). Is, which has the lowest loss rate.

Blood sample were collected from 260 1.5 fingerling (3-5gr) sturgeons (Acipenser persists IS and A. STELLATUS). The fish were apperantly healty) and captured from fish farms of Gilan province (Sangar dam) during summer. In blood smears the mature erythrocyte were oval with and abundant pale pink cytoplasm and acentrally positioned oval nucles. A slight number of 1.5 immature erythrocytes (Polychromatocytes) were observed. These cell appeared more rounded, I and have slightly basophilic cytoplasm. The total, RBC were (A. persicus, A. STELLATUS) 0.881x106±0.02, 0.861x106±0.03 per mm3, respectively and hematocrit 30.00±0.70, 28.88±0.64 percent, and hemoglobin 6.73±0.15, 6.66±0.14 gr/dl respectively. The total WBC were (A. Persicus, A. STELLATUS) 4284.28±172. 18  4140.00±185. 10 per mm3 and heterophil, 41.60±2.26, 40.62±1.42 percent and Lymphocyte, 45.82±1.71, 44.77±1.28 percent and, monocyte, 0.342±0.12, 0514±0.15 percent and, eosinophil, 12.20±1.31, 12. 65±0.97 percent and, band cell 0.742±0.20, 0.971±0.26 percent and  meta myelocyte, 0.342±0.15, 0.285±12 percent respectively. 

In order to evaluating the relationship between osmotic-ionic changes and sexual maturation stages, 30 farmed Acipenser STELLATUS were selected and were studied for a 1 year period. There was a significant difference in serum osmolarity of males and females at sexual maturation stages in different seasons (P<0.05). Results of ion concentration (sodium, potassium, calcium and magnesium) showed no significance different at early stages (P>0.05), but Ca2+ was decreased significantly (P<0.05) at the stage IV in different seasons with development of sexual maturation and was minimum in spring (8.85±1.49 mEq/L). Concentration of Mg2+ showed a various fluctuation in different seasons with development of sexual maturation and decreased to its minimum concentration in spring (1.66±0.26 mEq/L). In males, besides of Ca2+ and Mg2+, Na+ also showed different fluctuation in different seasons and reached to its minimum concentration in spring (132.66±2.56 mEq/L). According to observed results, there was a direct relationship between osmolarity and sodium ion in males and females. Also, there was a significant difference between calcium ion and sexual maturity development. Therefore it can be concluded that sodium has a major role in osmoregulation and also we give emphasis on calcium ion as major sexual indices in A. STELLATUS.

Sturgeons as the precious commercial fishes have co-evolved a number of adaptations to their habitat and lifestyle. The relationship between brain morphology and behavioral ecology has been confirmed in many chondrichthyes and teleost fish species. However, very little is known on the central nervous systems of sturgeon species. In this research, the relative brain size (encephalization) and the relative development of four brain areas in two sturgeons are investigated. Two integration areas (the telencephalon and the metencephalon or corpus cerebellum) and two sensory brain areas (mesencephalon and myelencephalon which receive primary projections from eye and octavolateralis senses, respectively) are examined. The analysis of brain size reveals that the integration area is developed more that the sensory area. The volume of cerebellum is significantly large in theses species, comprising up to two third of the total volume of brain. This is different from brain development of most teleost and chondrichthyes species, which have large mesencephalon and telencephalon, respectively. This study suggests that sturgeons have evolved different sensory strategies to cope with the demands of life in the depth of the sea.   

Abstract This study was conducted to investigate the effect of different levels of phospholipids on fatty acid profile, lipid content of body and lipase activity in stellate fish (Acipenser STELLATUS) fed different levels of lecithin as phospholipid source. The fish with average weight of 11. 25 ± 0. 06 g were fed seven different diets having identical levels of protein and lipid content but different levels of soy bean lecithin (1, 2, 4, 6, 8 and 10 percent) for 11 weeks. The fish were fed at satiety during experimental period. The results showed that using up to 10% soy bean lecithin in the fish diet increased linoleic, saturated fatty acids (SFA) and n-6 highly unsaturated fatty acids (n-6 HUFA) significantly in the fish body (p<0. 05), whereas there was no significant difference in EPA and DHA levels. The results revealed that the body fat composition is significantly influenced with the fat content in the diet, however, maximum lipid was observed in fish fed 6% lecithin. The lipase activity in the digestive system of stellate fish increased significantly in the groups fed 2-4% lecithin. Therefore, we can conclude that increase in soy bean lecithin level of diet up to 4 and 6% can significantly increase the lipase activity and SFA, al MUFA and n-6 HUFA fatty acids level in the stellate fish at this weight range respectively.