سید رضا سید مرتضایی

The present research was started in 2016 at Bandar Imam Khomeini Marine Fish Research Station. The aim of this project was to produce fertile broodstock and achieve the biotechnique of larval propagation and fry production of the Asian sea bass. In this regard, the Thai fry strain were introduced in the station over three different years and their breeding was done until the pre-breeding stage. After four years, 3- and 4-year-old female pre-brooders and 1.5-year-old male pre-brooders were produced, and in the summer of 2022, these brooders were propagated by artificial reproduction method through injecting. In Khuzestan, the reproduction season begins from June to the end of September at a temperature between 28 and 34 ºC. The fish spawning occurs between 36 and 40 h after injection at midnight. The LHRH-α2 hormone was injected intramuscularly for the artificial reproduction of this species. The percentage of fertilization, hatching, and survival of 3-day-old larvae of Asian sea bass in different months varied between 78-92%, 82-93%, and 75-85%, respectively. From February 2022 to July 2023, 208 brooders were donated to 5 private hatchery sectors in Khuzestan and Hormozgan provinces for the mass seed production of this species. The results of the current project showed that the establishment of biosecurity is the most important principle in the implementation of breeding programs, domestication of new marine fish candidates, and selective breeding programs. Also, Asian sea bass has great potential for reproduction in captivity and mass fry production, and it can help short-term programs for the development of marine cage culture in the southern waters of Iran.

In order to investigate the resistance of shrimp against white spot disease by Gracilaria corticata algae, 300 Vannamei shrimp in two groups were fed with and without algae extract for 14 days. At the end of the experiment, half of the shrimp of each group were exposed to the white spot virus. After the challenge, during days 0, 3, 9, 18 and 25, the survival rate and immune factors of shrimp were examined. According to the results, survival rate of shrimp fed with algae extract was higher than the shrimp were fed by commercial pellet without the algae extract (positive control) significantly (P < 0.05). Immune system enhancement from the first to twenty fifth day and the highest levels of THC, TPP, SOD, POD and PO were observed in group Algae on twenty fifth day of the experiment. This condition was also observed in group AV, but less than group A with a significant difference (P <0.05). Considering the function of algae in stimulating the immune system, it seems that during the culture period, algae supplementation in the diet can be used as a proposed strategy to control white spot disease.

Biofloc technology has mentioned as a new tool for sustainable aquaculture development and has overcome the problems of water scarcity and discharge of aquaculture effluents to the environment. In this system, nitrogenous wastes (Ammonia and Ammonium) are simultaneously recovered by bacteria and converted into microbial proteins that can be consumed by aquatic animals. The purpose of this study was to investigate the factors affecting the production of biofloc and evaluate it for use in aquaculture. The effect of different temperature levels (24, 28, 32 °C), salinity (0, 4, 8 g/l)  ,and C/N ratio (10:1, 15:1, 20:1) which are the main key factors to the formation and function of biofloc system was evaluated by using a response surface method designing. Moreover, the influence of those factors on total ammonia nitrogen, nitrite, nitrate, floc volume, protein, and lipid content of biofloc was investigated. The results showed that the temperature had a significant effect on floc volume and protein content of biofloc (P < 0.05), but it had no significant effect on other nitrogenous compounds and lipid content (p > 0.05). The protein, lipid and moisture of biofloc particles were decreased by increasing salinity significantly (P < 0.05). Also, TAN and nitrite concentration influenced by C/N ratio inversely. According to the factors Optimization, providing 27 °C and C/N ratio of 18:1 in brackish water and 29 °C and C/N ratio of 14:1 in fresh water resulted in high quality biofloc production and control of nitrogenous wastes in water.

Pheromones are molecular signals of hormones or their derivatives that affect the same species in the environment outside the body. The effect of ovary extract of psyllium as a pheromone-containing substance (PGF2α) on pheromone induction and the process of final sexual maturation and changes in male sperm indices of this fish have been investigated and compared in different treatments. Male fish with an average weight of 45 ± 200 g were released in 300 liter fiberglass ponds and after adapting the fish to the environment (for 48 hours), the experiments were performed in 5 experimental groups (one control group, one prostate gland control group and 3 groups Treatment) in which each group consisted of 9 adult male fish. Different concentrations of ovarian extract were added to the water in three treatments of 5, 10 and 15 mg / l as a bath. After 24 hours, the fish were anesthetized and fish biometrics was performed by measuring length and weight. After blood sampling, fish gonads were weighed. The results showed that pheromone induction of ovarian extracts and their positive effect on increasing the rate of sperm counts. Gonadosomatic index as well as testosterone levels at 10 and 15 mg / l treatment and prostaglandin treatment (PGF2α) were significantly increased compared to the control (p <0.001). Sperm density and spermatocrit in the treatment of 15 mg / l (T3) had a significant decrease compared to the control, but the indices of sperm motility rate and sperm motility percentage compared to the control did not show a significant difference. Relative sperm volume in all treatments was affected by pheromone extract and a significant increase was observed compared to the control in T3 treatment (p <0.001). Administration of pheromone extract resulted in control of male reproductive fish reproduction in all experimental groups.

An experiment was conducted to evaluate the effect of biofloc system on water quality, growth performance, immunity and body composition of Nile tilapia at different stocking densities. Fry (3.2±0.05 g) stocked in 500 and 1000/m3 in biofloc and clear water system (as control) in three replicates and reared for 50 days. Results showed that the lowest TAN and highest nitrite and nitrate were observed in BFT treatments. Total suspended solid, floc volume and bacteria increased by increasing stocking density. Maximum final weight (12.9g), SGR (3.21 %/day), survival (100%) and the best FCR (0.91) were obtained in BFT (500/m3). There were no significant differences in survival among treatments (p>0.05). Lysozyme, immunoglobulin and catalase of fishes in the biofloc treatments were significantly (p<0.05) better than control. Proximate analysis revealed that protein and lipid content of fishes in BFT were slightly higher than control groups but these differences were not significant. It seems that although fishes in BFT 500/m3 statistically showed better indices than others but due to small differences in growth indices and feed conversion ratio in one hand and no difference in survival rate between 500 and 1000/m3. On the other hands, the study suggests the stocking density of 1000/m3 for larviculture of tilapia in biofloc system to use water and equipment more efficiently.

White spot disease (WSD) is one of the shrimp lethal viral diseases that causes heavy losses on all shrimp of Penaeid family. In this study comparison of histopathological effects of Red algae Gracillaria corticata dietary in shrimp challenged to white spot syndrome virus was investigated. For this aim 1200 SPF white leg shrimp (L. vannamei) sub adult with average weight of 10±1.02 g was collected and divided to four groups. The first group (T1) fed G. corticata powder was mixed with shrimp feed (2 g/Kg), second group (T2) fed G. corticata (2 g/ Kg) and after 14 days injected with WSSV and all groups maintained for 25 days, third group (T3) fed with commercial pellet and fourth group fed with commercial pellet and then injected with WSSV and all group maintained for 25 days. For histopathology survey, the samples of gills, hepatopancreas, lymphoid tissue, stomach and gut were fixed in davidson solution. Tissues were embedded in paraffin wax, sectioned at 5µm and stained with hematoxylin-floxin eosin. The histopathology results indicated that samples fed with algae and positive control in the face of white spot syndrome virus were inclusion body cells observed in gills, stomach, gut and hepatopancreas.  Survival rate in T2 group was higher and significantly different (p < 0.05) from T4.

Cage fish farming is one of the most suitable aquaculture methods in inland water resources, which is an opportunity to increase protein production in the country. In the present study, Seymareh Dam (in Badreh city in Ilam province) has been investigated with the aim of a feasibility study of cage fish farming. Abiotic factors (physical and chemical parameters of water) were studied in three stations in Seymareh Dam Lake and one station in the riverine zone of the dam. According to the results, during the year, the range of changes in physical and chemical parameters of water, including water temperature, DO, EC, and pH were determined 6.29-5.11°C, 2.38-3.36 mg/l, 788-2220 μS/cm and 7.8-0.9, respectively. The hydrochemical results showed that there were no restrictions for aquaculture except for water temperature. On the other hand, fishery studies showed the presence of carp and rainbow trout species in the lake. Therefore, due to the importance of water temperature for aquaculture, it is possible to breed cold-water fish (such as trout) in the second half of the year and carp (such as common carp) in the first half of the year in floating cages

The Gargar River is the eastern brunch of the Karoon River, which is separated in north of Shoushtar by regulatory dam (Bandmizan) from its western branch, Shotaeit, and is about 78 km later, join to the Shotaeit and Dez and create the big Karoon. This river, while supplying drinking water to Shoshtar, Haftgel, and part of Ramhormoz and its villages, is one of the great poles of the province's fish culture. The aim of this study was to evaluate the microbial quality of surface waters of the Gargar River, compare the microbial contamination at upstream and downstream stations as well as comparisons with EPA standards to determine different uses. For this purpose, 6 stations were selected and sampling was conducted monthly within one year and microbial indices including total bacterial count, total coliform count and fecal coliform count were evaluated. The results showed that maximum of the 3 microbial indicators was at the station 2, after the sewage discharge of Shushtar (respectively 15.24×103 CFU/mL, 68181.82, 3380.91MPN/100mL) and the minimum value was at the station 1 at the upstream river (respectively 2.8×103 CFU/mL, 2627.27, 1062.73MPN/100mL). The microbial indices varied depending on seasonal variation, sampling time and location and the final results of this study showed that the water quality of river is inferior and not suitable for human use.

Factors such as increased global consumption of fish reduced marine fish harvesting, profitability and economics have increased the interest in fish culture in the cage. Fish culture needs a desirable water quality which is the best way to achieve optimum survival and growth. The purpose of this research is to investigate the water quality in terms of being suitable for fish cage culture in the Aras Dam Reservoir in West Azarbaijan. Sampling was carried out from 3 sites each with seasonal period from summer 2017 to spring 2018. Sampling was performed on the entrance, middle of the Lake and the crown of the dam from the water surface. Water temperature (º C), E.C. (µs/cm), T.D.S.(mg/L), was measured with WTW E.C.meter, pH with WTW pH meter, DO (mg/L) using oximeter WTW model 320. The TSI trophy index was calculated based on the parameters of total phosphorus and secshi-disc depth.  The transparency of water varied from 0.5 to 1.3 m between sampling sites. Generally, the TP at each sampling site was higher in summer than the other seasons. The trophic condition of the Aras dam is the hypertrophy which indicates the high phosphorus load and contamination from the agricultural runoff in the lake. The concept of carrying capacity, shortage of fresh water sources and the presence of hypertrophic conditions in all sites and seasons indicate that the ecological conditions of the Aras dam are not suitable for fish cage culture, and therefore is not recommended.

Reservoirs are artificial lakes that have been created by humans for specific purposes. Water reservoirs has different uses which the most important are: municipal water supply, agricultural irrigation, aquaculture, power generation and etc. According to increasing of water demand the accurate study of water resources, determination of their pollutants, prevention, pollution control and optimal use of available water resources are required. Saymareh Dam is located about 40 km northwest of DARREH SHAHR in ILAM province. This dam was constructed with the aim of producing electric power, controlling and regulating of river floods. The aim of this study was to survey on the bacterial contamination of Seymareh Reservoir and its relationship to some water physical and chemical factors. According to the geographical and hydrological status of the reservoir, five stations (one station near the water entrance to the lake, 3 stations at the beginning of the lake, middle and near the crown, and one station after the reservoir) were sampled 8 months in 3 seasons of year for bacteriological, physical and chemical evaluation. Water quality standards for microbiological sampling were used. Then microbial tests including total bacterial count, total coliform count, fecal coliform and fecal streptococcus count were performed. In each station simultaneous measurements of some physical and chemical parameters of water (temperature, dissolved oxygen and pH) were also evaluated. The results showed that the highest total bacteria counted during sampling at station 5 (after reservoir) and the lowest rate at station 4 (before the reservoir's crown). Also the average of total and fecal coliform was the highest at station 5 in all sampling seasons and the lowest in station 2. The stations grouping in this three indices showed that the entrance and outlet stations of the reservoir (1 and 5) are in the same group and the stations located on the reservoir (2, 3 and 4) are in the other group that showed a significant difference (p<0.05).In the Pearson test, correlation between water temperature and pH changes with the number of total bacteria and fecal coliform was positive and with the total coliform was negative, while dissolved oxygen showed a negative correlation with three bacterial indexes. In comparison to the bacterial parameters with available aquaculture standards, the water of this reservoir is suitable for fish production in all seasons.