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In order to does this study, 150 Persian sturgeons having 75g mean weight transferred to 500 liter tanks. After dividing the fishes into two groups (experimental and control), the fingerlings fed by concentrate food that contained different levels of Zataria multiflora essential oil (15, 25, 50, 100 g/kg) for 8 weeks. Finally, sampling carried out on blood and serum of fishes. After preparing the samples based on standard methods, hematology and serology studies, performed. The results showed significant difference in mean of monocytes between experimental and control groups (P<0.05). In treatment 25g/kg, monocyte count was more than other treatments. But there were no significant differences in mean and standard deviation of other white blood cells. The results of serologic studies showed no significant differences in serum indices (C3, C4 and total protein) (P>0.05), but there is significant difference in mean and standard deviation of albumin. So that, the average in treatments 15 and 25g/kg and control group was more than treatments 50 and 100g/kg of Zataria multiflora essential oil.

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Twenty four farmed great sturgeon, Huso huso (including 8 males and 16 females) over 6 years old were used to develop a method for determination of sex and maturity stages. Seasonal gonadal tissue and blood samples were collected from farmed great sturgeon for three years. The sex and stages of maturity were determined by histology and laparoscopy at the beginning and end of experiment. Plasma sex steroid hormone levels [testosterone (T), 17β-estradiol (E2) and progesterone (P)] were measured by radioimmunoassay, and plasma calcium ion levels were measured by spectrophotometer. Mean concentrations of testosterone, progesterone and estradiol in blood plasma of H. huso at maturity stages II, III and IV were 10.86±1.63, 54.14±3.1, 112.41±7.4 0.84±0.12, 15.66±2.18, 50.75±3.63 ng/ml in males and 9.0±1.39, 6.51± 0.64, 2.95±2.29, 5.45±0.29, 9.47±0.97 and 4.15±0.7 ng/ml in females, respectively. Testosterone and estradiol levels showed significant differences at various stages. Calcium level at stages II, III and IV of sexual maturity in females (8.05 ± 0.09, 10.4 ± 0.34 and 9.6 ± 0.6 mg/dl) was more than males (7.73 ± 0.16, 8.58 ± 0.13 and 8.76 ± 0.11 mg/dl). Results showed that steroid hormone concentration and calcium level of blood plasma in males and females vary between different stages of sexual maturity. Therefore it can be used to determine the stages of sexual maturity in farmed H. huso.

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This is the first study of growth and age of Sardinella sindensis from coastal waters of Qeshm Island (Persian Gulf) based on the sectioned otolith reading method. In total, 128 fishes were collected randomly from purse seine commercial nets during March 2011 to February 2012. The annual formation of the growth rings were determined by counting the opaque and translucent zones occurrence at the outer margin of the otolith. The peak of opaque and translucent zones formation occurred in June and January, respectively. There was no significant differences between the sex ratio of males to females (p>0.05). The total length and body weight for both sexes ranged between (7.9-18.6 cm) and (3.98-55.69 g). In total, four age classes were determined, and the maximum age was recorded as 3.5 years. The most abundant individuals were counted in 1+ age class, while the least number of fishes belonged to the 3+ age class. The non-linear regression relationship between the length and age for combined sexes were fitted in Von Bertalanffy growth equation, and described as: TL= 20.8 (1-e-0.54(t+ 0.54)). There was a strong relationship between the body weight and total length of the fishes (p>0.05), indicating that the growth type of S. sindensis is isometric. From the results of this study we concluded that S. sindensis is a fast-growing species with a short-life span. In order to obtain more reliable results about the age and growth of this species, we suggest that different methods of age determination should be used, combined with the evaluation of the factors affecting its growth for the management of optimum exploitation of the resources of this fish.

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Reef-building coral harbor communities of photosynthetic taxa of the genus Symbiodinium (zooxanthellae). The genus Symbiodinium is currently classified into nine genetic clades (A–I). Various corals harbor different Symbiodinium clades; some show specificity to a single strain. Coral and their zooxanthellae are sensitive to environmental stresses. In the Persian Gulf, coral reefs are subject to harsh environmental conditions including extreme temperatures and high salinity. This is the first study to use clade specific primers to clarify the diversity of Symbiodinium in each coral species of Larak Island. For this purpose six coral species were collected at two different locations in Larak Island. After DNA extraction, PCR amplification was performed using clade specific primers. The results showed that multiple Symbiodinium clades are hosted by most coral species. In addition, among thirteen obtained Symbiodinium sequences, the frequency of either tree clades, A, C and D was almost the same. Corals species may contain different clades of Symbiodinium depending on the region and on the tolerance characteristics of each clade. Thus, knowledge of zooxanthellae diversity associated with scleractinian can contribute to a better understanding of the sensitivity of corals to environmental conditions.
 

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Reproduction biology and feeding habits of black mouth croaker, Atrobucca nibe, was investigated monthly from September 2013 to August 2014 in the Oman Sea. The specimens were collected by bottom trawl in the Northwest of Oman Sea. A total of 637 fish specimens examined, 284 males and 353 females were sexed. The average sex ratio was F: M= 1.24:1, showing dominance of females over the males. Spawning season of A. nibe was mostly observed in June and October but spawning might be occurred in all year long . The mean absolute fecundity was calculated 97008±55553 eggs, with a moderate linear relationship between absolute fecundity and total length (Fecundity= 10802TL-280712, R²=0.7624). The mean length at first sexual maturity (Lm50 %) was 35 cm for females. A. nibe is an abstemious feeder according to the high vacuity index (VI=86.5±16.8 %). Skinny cheek lanternfish (65%), Japanese threadfin bream (13%) and deep-sea shrimps (11%) were the frequent food items of this species. Results showed that  bony fishes were consumed by all size-classes, skinny cheek lanternfish (42.1%) and Japanese threadfin bream (79.4%) were more pronounced in size-class of 34-38 cm, and also  crustacean were more frequent (29%) in 22-26 cm size classes.

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The assemblage structure of bottom associated fishes across the northern coast of the Persian Gulf has received little attention. The present study was conducted in the waters more than 10 m. of northeast coasts of the Persian Gulf. The autumn data of a bottom trawl survey targeting demersal fishes were used to describe the assemblage structures and their response to environmental variables. A total of 165 and 145 demersal fish species were sampled in 2014 and 2016, respectively. The assemblages were dominated by bony fishes, prevailed by Gilded goatfish (Upeneus doriae), followed by batoid fishes, prevailed by the Arabian banded whipray (Maculabatis randalli), and sharks, prevailed by Whitecheek shark (Carcharhinus dussumieri). The results indicated a reduction in the species richness over the two-year periods in the studied area. The highest species richness was observed at depths of 20 to 30 meters, with a downward trend to shallower and deeper waters. The BEST routine showed that temperature, EC, salinity and pH best described the distribution pattern of bottom-associated fishes in both years. Additionally, CCA analysis demonstrated three bathymetrical assemblage structures for bottom-associated fishes in the studied area. Among different environmental variables, the depth seems to be a major one distinguishing the communities.