a. hallajian

Gender and sexual maturity stages of great sturgeon (Huso huso) were studied using blood plasma sex steroids hormones ratios (17β-estradiol (E2), testosterone (T) and 11-ketotestostrone (11KT)}. One hundred sixty reared great sturgeon aged (1-12 years) with weight and length 0.45 to 49.65 kg and 36-198 cm, respectively. For each gender, 80 individuals (20 fish in each maturity stage) were selected out of 650 fish. Hormone concentrations measured with commercial kits. All samples analyzed in duplicate and a separate standard curve run for each ELISA plate. The findings of this study showed that it is possible to separate male and female fish especially from the second sex maturation stage using T/E2 and 11KT/E2 hormone ratios. The results showed that the use of E2/T, E2/11KT ratios are very useful indices for sex determination and sexual maturity stages assessment in male reared great sturgeon, but T/11KT and 11KT/T ratios were not functional. Based on the results, the use of T/E2 and 11KT/E2 ratios were preferable to E2/T and E2/11KT ratios for recognition of different sex maturation stages in male fish. These hormone ratios were used to determine different stages of male sexuality with more than 95% precision, and less than 30% for females. In addition, despite strong correlation between length and weight of fish with hormone ratios, sex could not identified through this parameter. The results of the present study revealed that some sex steroid hormones ratios can determine the sex and sex stages of reared great sturgeon especially in males with high accuracy.

Persian sturgeon (Acipenser persicus) is one of the most valuable species of fish native in the Caspian Sea and Iran's waters. In order to evaluate the heritability of reproductive traits in wild Persian sturgeon (A. persicus) three males and three  females’ fish were caught in the southern area of Caspian Sea and then were crossed by using a 3×3 factorial with the aim of selecting the best parent to produce good larvae. Prior to the crossing, sperm density, motility, pH and osmolality, spermatocrit percentages, and the number of micropyles on the eggs` surface were determined. One hundred grams of eggs from each females were fertilized by 1mL of sperm from each males for a total of and 9 treatments combinations, (F1M1, F1M2, F1M3, F2M1, F2M2, F2M3, F3M1, F3M2 and F3M3) with 3 replicates each. Hatching percent was calculated at 5 h after fertilization and 405 eggs were measured for weighting and determining their diameter. Sperm concentration and number of micropyles had no significant effects on fertilization rate (p>0.05). Sperm density also had negative correlations with fertilization (r=-0.603, p<0.01) and hatching rates (r =-0.175, p<0.01). However, fertilization was positively correlated with osmolality (r=0.511) and number of micropyles (r = 0.574). The correlation between osmolality and hatching rate was 0.288 and between eggs weight and its diameter was 0.698. Heritability estimates for weight and diameter of eggs were 0.043±0.035 and 0.207±0.103, respectively. The results show treatment 9 (F3M3) had higher genetic values compared to the rest of the treatments. Also due to the large number of micropyle on sturgeon ova, in order to increase the percentage of fertilization rate, sperm density should be low but motility duration should be high.

The effects of different light regimes (24L: 0D, 150 lux, 12L: 12D, 300lux, 0L: 24D, 0 lux, and control treatment) on growth, melatonin concentration, and Insulin-like growth factors gene expression of Persian sturgeon (Acipenser persicus) embryos were evaluated. Four groups of Persian sturgeon eggs (450 g) were incubated in Youshchenkov incubators with three replications for each treatment. The experiment was conducted during an 8- day period of incubation. Growth rate, plasma melatonin levels, and IGF-growth factors were investigated at 1, 4, and 8 days post fertilization.  Results showed that higher mean weights growth were observed in fertilized eggs exposed to a 24L: 0D photoperiod with 150lux light intensity (p<0.05). The larval body length and hatching rate of fertilized eggs were significantly higher in embryos incubated at 12L: 12D with 300lux. The melatonin hormone level between sampling days and treatments were significantly different and it would be concluded that it may be related to the species. During the first-day post fertilization, the IGF-I and IGF-IR gene expression were significantly higher than other days. However, IGF-I and IGF-IR gene expression at different treatments showed no significant difference at day 4 and 8 post fertilization. According to the results, the stimulating role of IGF-I and IGF-IR gene expression in growth at the one-day post fertilization under different light regimes can be concluded. These findings suggest that the 12L:12D photoperiod with 300lux light intensity is the appropriate light regime for Persian sturgeon eggs incubation. The results of the present study would provide fundamental information for further use of light regimes during the early development of sturgeon larvae to optimize rearing protocols in sturgeon hatcheries.

This study aims to elucidate the toxic impact of zinc on hematological indices of the farmed Silver Carp (Hypophthalmichthys molitrix). In this study, after adaptation 135 fish specimens with the length of 13±1 cm and the weight of 50±10 gr were put in one control treatment and 2 experimental treatments contained of 5 and 10 mg/L (Zn (no) 3)2 in 90 liter aquariums. Blood samples were taken from the caudal vein after 12, 24, 48, 72 and 96 hours. Results showed that, hematocrite (Hct), hemoglobin levels (Hb), mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) increased significantly (p<0/05). The number of White Blood Cell (WBC) on 5 mg/L and 10 mg/lit treatments until 72 hours decreased significantly but after 96 hours it increased significantly (P<0/05). The number of Red Blood Cells (RBC) decreased significantly until 96 hours (P<0/05). According to the results, blood parameters were sensitive factors in monitoring the toxicity and the stress caused by zinc particularly in acute concentrations.

Great sturgeon is one of the most economically important species. However, in recent years overfishing, illegal fishing, etc., have resulted in severe declines in the stocks of this species. For conservation, stock of this species, determination of gonadal situation and its gonadal growth exchanges is very important. This paper is a histological approach to gonadal staging in 74 Huso huso in the 4 – and - 5 - year old classes. The fishes were reared in brackish water concert tanks under controlled conditions. A small section of the gonads of each fish was removed by biopsy. The gonadal tissue was fixed in buoin solution. They were dehydrated in different diluted solutions of alcohol and chloroform until they were clear. Then they were embedded in paraffin and sectioned at 7 µm and stained by hematoxylin and eosin method. Of the four-year old fish, %56 and %44 were males and females, respectively. %6 of males were at stage I %11 stage I-II %61 stage II %13 stage II-III %11 stage III-IV and %8 were at stage IV-V. %3 of the females were at unknown stage %3 stage I %11 stage I-II %60 stage II %14 stage II-III and 9% stage III. Of the 5 year old fish, %12.5 of males were at stage II % 25 stages II-III %50 stages III and %12.5 were at stage IV. %62.5 of females were at stage II and %37.5 were at stage II-III. Results of this study Compared with those obtained from fishes of the same age class studied in natural habitats as well as the results obtained for the farmed sturgeons from freshwater medium indicate that there is no similarly in the stage of gonadal development in different conditions. Longest stage in tow sexes was stage II that is longer in females, and passing of stage II in males is faster. Males showed more sexual maturity than females. Gonadic growth in culture medium is faster than wild condition, and it is faster in brackish water than fresh water. So, we can state that brackish water is a suitable medium for gonadic growth of Great sturgeon.