مجله علمی شیلات ایران
سال سی و دوم شماره 2 (پیاپی 136، خرداد و تیر 1402)

Thiamine, or vitamin B1, is an important coenzyme in lipid, carbohydrate, and protein metabolism that plays a vital role in the embryonic stages and larval development. To evaluate the effects of thiamine on incubation indices of beluga Huso huso, eggs obtained from farmed males and females after fertilization were immersion in water-soluble thiamine with four treatments and two replicates including control (0 mg thiamine per liter of water), T500 (500 mg thiamine per liter of water), T1000 (1000 mg thiamine per liter of water) and T1500 (1500 mg thiamine per liter of water) during water hardening for 30 minutes. Then, eggs were washed five times with fresh water and kept in special incubators until hatching. Incubation indices and larval growth were investigated 24 hours after fertilization to 44 days after starting feeding. Results showed the highest and lowest egg survival at 24 hours after fertilization until hatching were observed in T1500 and control, respectively (P<0.05). At the start of the feeding the results showed no significant difference in larval weight and length (P>0.05). However, thiamine increased the weight, length, and weight gain in T1000 and T1500 at the end of the experiment (P<0.05). Egg immersion in soluble Thiamine led to an increase in the specific growth rate and body weight in T1000 and T1500 at day 36 after the start of feeding (P<0.05). The food conversion ratio, protein efficiency ratio, and lipid efficiency ratio significantly decreased in control and T500 compared to other treatments (P<0.05). The lowest larval survival was observed in control at the beginning of feeding until day 44 (P<0.05). The results of this study indicate that immersion of eggs in thiamine solution can increase larval growth and survival. Therefore, it is recommended that beluga eggs immersion in thiamine solution at least 1000 mg L-1 thiamine after fertilization

Tetraselmis tetrathele is a species of saltwater that is widely used in industry and aquaculture due to its high nutritional value, bioactive compounds, and ease of cultivation. In this study, mass cultivation of this species was evaluated using effluent from dairy and yeast factories to evaluate growth, viability, and biochemical compounds (protein, fat, carbohydrate). The experiment was performed in a completely randomized design with six treatments; Conway, raw milk and yeast effluents as culture media, each in two modes, diluted (5 ml per liter of culture medium) and concentrated (10 ml per liter of culture medium) for 11 days. The results showed that this species was able to grow on dairy and yeast wastewaters, but the highest cell density in diluted Conway (9.12 × 106 cells per ml and 0.87 per day) and the highest specific growth rate in diluted yeast (6.68 × 106 cells per ml and 2.84 per day) were measured. However, the diluted raw dairy treatment had more survival than other treatments. The highest amount of protein and fat was obtained in the concentrated dairy treatment (44.6% and 9.71% of dry weight, respectively) and the highest amount of carbohydrates was obtained in the concentrated yeast treatment (31.49% of dry weight). Based on the specific growth rate, viability, and biochemical compositions it can be concluded that dairy and yeast wastewaters can be used as a suitable semi-industrial culture medium for mass cultivation of this species and it is recommended for the production of bioactive compounds and biofuels from the obtained biomass.

In this study, relative growth, sexual dimorphism, and morphometric maturity of Ocypode rotundata and Austruca iranica were investigated on western south and northern of Qeshm Island. The samples were collected in February 2021. Based on the carapace width, the males of O. rotundata (33.1 mm) and males of A. iranica (12.4 mm) had average carapace width more than female crabs (32.2 mm and 11.2 mm). The male and female of A. iranica and O. rotundata had significantly different between three (first part of abdomen width, fourth part of abdomen width, and sixth part of abdomen width) and four (abdomen length, first part of abdomen width, and fourth part of abdomen width, sixth part of abdomen width) traits, respectively (p< 0.05). The calculated values of CW50 based on the morphometric maturity for O. rotundata males with three methods of common, Bootstrap and Bayesian were 33.02 mm, 32.82 mm, and 33.05 mm, respectively. This value was 29 mm for female crabs with three methods. Also, the morphometric maturity values for males and females of A. iranica were similar to the three performed methods. The values in the male and female were obtained 11.61 mm and 9.15 mm, respectively. Based on the results, the CW50 value in the male crabs for both studied species was more than the female crabs.

This study aimed to evaluate the effect of 2-phenoxyethanol on antioxidant enzymes capacity including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in various tissues (blood, mucus, brain, gill, and liver) of rainbow trout (Oncorhynchus mykiss) at immediately and 24 h after induction anesthesia. First, the fish (n=180, with an average weight of 5.82±0.8) were divided into six groups (each group with 3 repetitions) and exposed to 0.2, 0.3, 0.4, 0.5, and 0.6 mL/L of 2-phenoxyethanol for the determination of its lowest concentration for inducing anesthesia. The minimum concentration for anesthesia was determined 0.3 mL/L. Then, 72 fish (with an average weight of 5.79±0.73) were assigned to control and experiment groups (36 fish in each group) to evaluate the effect of this concentration of anesthetic on antioxidant enzymes capacity in various tissues of rainbow trout. The samples of blood serum, mucus, and tissue extract (brain, gill, and liver) were prepared from fish in each group, along with measuring various enzymes (SOD, CAT, and GPx) and protein, at 0 (immediately after anesthesia) and 24 h (after induction anesthesia). The results showed that the anesthetic 2-phenoxyethanol inhibited the antioxidant capacities in different tissues, probably through the increase of reactive oxygen species (ROS) and oxidative damage. The comparing the results of the capacity of antioxidant enzymes in different tissues of rainbow trout anesthetized with 2-phenoxyethanol and the obvious difference in the downward or upward course of these enzymes shows that the non-invasive method (mucus and blood samples) to express the status of the antioxidant defense system of rainbow trout is not suitable when faced with the anesthetic 2-phenoxyethanol.

Little is known about complement system as a component of innate immunity of the ectothermic vertebrates such as crocodiles. Serum complement is valuable tool in determining the health status of turtles. In this research effect of concentration, volume and temperature on alternative complement pathway activity of Mugger crocodiles (Crocodylus palustris) using standard haemolytic assays was studied. For this purpose, Crocodylus palustris serum complement hemolysis in different concentrations, volumes and temperatures was measured. Results indicated significant relation between relation measured hemolysis and concentration, volume and temperature (p<0.05). The measure of hemolysis in various concentrations (25%, 50% and 100%), volumes (10, 20, 30 µL) and temperatures (5-35°C) were significantly increased (p<0.05). The results show that alternative complement pathway activity of crocodiles might affect concentration, volume and temperature that it caused increased non-specific immunity and the resistance to the outbreak of diseases.

The present study was carried out to investigate the effect of different dietary levels of fermented canola meal by the Bacillus isolated from Caspian Sea sediments on growth and nutritional indices, proximate body composition, and digestive enzymes activity of Nile tilapia fingerlings. A total of 225 fry fish with an average weight of 1.90±0.05 g were fed with five different experimental diets including treatment 1: a diet without fermented canola, treatment 2: a diet containing 12.5% ​fermented canola, treatment 3: a diet containing 25% fermented canola, treatment 4: a diet containing 37.5% fermented canola, and treatment 5: a diet containing 50% fermented canola for 8 weeks. Results revealed that the growth and nutrition indices did not significantly differ among various experimental groups (p>0.05). Proximate analyses of the body composition showed that the protein contents of treatments 2, 3, and 4, the lipid and moisture contents of treatments 3, 4, and 5, and also the ash contents of treatments 4 and 5 were increased compared to the control group (p<0.05). Also, the results of digestive enzymes activity showed that the alkaline protease activity of treatments 3 and 4, lipase activity of treatments 2 and 3 and also the alpha amylase activity of treatment 3 were increased in comparison with the control group (p<0.05). In general, it was concluded that incorporating 50% of fermented canola did not affect growth performance and nutritional indices in Nile tilapia fingerlings.

In this study, the relationship between water physicochemical parameters (sampling of water and soil) and Babylon snail biomass was done by sampling from four fishing grounds of this species in the north of the Oman Sea including Pasabandar, Breis, Pozm, and Konarak from September 2021 to September 2022 by circular cages. The average values of different physicochemical parameters (pH, salinity, turbidity, TOM, dissolved oxygen, and sand and silt) and different nutrients (nitrate, phosphate, ammonia, and nitrite) in the before and after seasons (monsoon) did not show a significant difference (p>0.05) through one-way variance analysis (between several periods) comparison of averages. Temperature and silt parameters from different seasons (before and after monsoon) had significant differences (p<0.05). Multi-layer artificial neural network was used for the correlation among the snail biomass, physicochemical parameters, and water nutrients and it showed that Temperatures and Nitrite were the most impact parameters on (snail biomass). From September to November, the highest catch rate was observed and it was the main season of Babylon snail fishing in Sistan and Baluchistan region due to the decrease in the water temperature and increase in the nitrite content. This study can be considered for fishing sustainability, basic management in exploitation, and a better understanding of the biological and demographic characteristics of this snail species.

In this study, the effect of different dietary levels of selenium on the growth of survival and muscle chemical composition of rainbow trout (Oncorhynchus mykiss) with an average weight of  80±0.57 g was investigated for 60 days. 320 fish were distributed randomly in 12 fiber tanks of 1500 L. Selenium was added at four levels, no selenium (control), 0.5 (treatment1), 1.5 (treatment2), and 3 (treatment3) mg/kilogram and the fish were fed for 6 weeks. The results showed that the specific growth rate, percentage of body weight gain, average daily growth, and food conversion ratio in the treatment fed with a diet containing 3 mg/kg selenium were significantly different from the control (p<0.05). There was no significant difference in the survival index between the investigated treatments and the control group (p>0.05). The effect of adding selenium on the chemical composition showed a significant difference in the level of carcass protein (p<0.05). The highest value related to treatment 4 (18.20±0.57 %) and the lowest value related to control group (16.47±0.16 %). In the treatments fed with selenium, a decrease in rainbowtrout fat was seen, which was significantly different from the control group (p<0.05). The moisture and ash levels in the control group were not significantly different from other treatments (p>0.05). The highest effect of selenium on growth was related to treatment 4 (3 mg/kg of selenium), but there was a significant difference with treatment 3 (1.5 mg/kg selenium) did not have (p>0.05). Overall, the results of this research showed the positive effect of adding 3 mg/kg selenium to the diet on the growth indices and improving the chemical composition of the rainbow trout.

This research was conducted with the aim of investigating the effectiveness of the mechanization status on energy efficiency in the dual-purpose farms of rainbow salmon breeding in the central province. This research was conducted by field method and through the analysis of questionnaire data regarding the state of mechanization in the farms of this province. For this purpose, after designing the questionnaires, the input information includes the area of cultivation and equipment such as feeding system, electric pumps, drainage pump, diesel generators and fans. The farms have been selected from 5 cities of Central Province, including 30 production units that have the largest share. Then the outputs, including degree, capacity and mechanization level, as well as production efficiency, production capacity, and energy efficiency were calculated by multi-input-output modeling and data envelopment analysis (DEA). The results showed that the variance of the degree of mechanization in the farms of this province is 0.96. Also, considering the optimal efficiency index level of 1 for farms, it was observed that 40% of farms in this province are in a favorable condition. The results of examining the performance of each unit in terms of energy efficiency index also showed that only 20% of farms in the province have an efficiency index higher than 0.4, and 80% have an energy efficiency of less than 1. The results show that the distribution pattern of mechanization in all farms of the province is not uniform and needs to be improved.

The aim of the study was to determine the quality of the inlet and outlet water of five selected rainbow trout breeding farms in Mazandaran Province (Haraz, Chalous, Tonekabon, and Sari) based on environmental parameters during four seasons in 2021-2022. Forty samples were collected and measured based on standard methods. According to the results, the range of water temperature (3.0-24.0°C), air temperature (2.0-25.0°C), DO (6.16-12.24 mg/l), BOD5 (0.24-2.76 mg/l), COD (2.40-93.70 mg/l), EC (284-783 µs/cm), turbidity (1.12-220-0 NTU), TSS (2-288 mg/l), pH (7.44-8.62), total phosphorus (0.2-2.12 mg/l), phosphate (0.01-0.206 mg/l), ammonium (0.012-0.538 mg/l), ammonia (0.001-0.018 mg/l), nitrite (0.001-0.426 mg/l), nitrate (0.52-6.10 mg/l), fecal coliform count (6-1000 CFU/100ml) and water quality index (WQIIR) (62.0-91.0) were registered. The water quality of this river was placed in class III (low pollution) based on the average parameters of organic pollution (BOD5 and COD) and human activities were not one of the main factors in the increase of organic matter in the river. The concentration of ammonium and nitrite was within the threshold limit, but the concentration of phosphate in all the inlet and outlet stations and in different seasons was more than the maximum limit of unpolluted rivers. The results showed that the WQIIR was in the range of 62-91. 7.5% of the total data and the mean of this index indicated the relatively good quality of the inlet and outlet water of the rainbow trout breeding farms. The highest quality of water, i.e. very good quality, is recorded in 12.5% of all data, which is observed at the inlet water of rainbow trout breeding farms. The outlet quality index of the farms was lower than its inlet, but it was categorized as good quality. The overall WQIIR (77.4±6.6) in all inlet and outlet stations indicates that the water of this farm is suitable for fish and wildlife and also suitable for rainbow trout breeding.