فصلنامه شیلات
سال هفتاد و پنجم شماره 3 (پاییز 1401)

TThis study examined the possibility of improving the quality of Macrbrachium rosenbergii larvae and water quality using different levels of Bacillus subtilis and Lactobacillus plantarum probiotics separately in semi-enclosed shrimp culture system. For the research conduction, 24000 newly hatched larvae of the giant freshwater shrimp obtained from the Ghasre-shirin hatchery center and were stocked in the experimental tanks by 40 larvae/liter density for one month. This experiment was designed in 25 liter tanks with four treatments; the first treatment (control without probiotic), the second treatment (106cfu/g), the third treatment (107cfu/g) and the fourth treatment (108cfu/g) in triplicates (for each of probiotics were designed separately). The results showed that with increasing the concentration of Bacillus subtilis probiotic up to 107 bacteria per gram, the parameters including DO, ORP, TDS, LSI and LCI have significantly an increase trend and at higher concentrations these parameters are reduced. It also showed that the bacterial density of Bacillus subtilis can be represented as a limiting factor and in higher concentration of 107 has negative results on larval growth and water quality. In L. plantarum probiotic treatment, increasing the number of bacteria, affected larvae quality and water quality, In the treatment of 108, the best probiotic performance of L. plantarum was recorded. In general, according to the results, the concentrations of 107 and 108 for B. subtilis and L. plantarum probiotics are respectively recommended in the hatchery centers of the giant freshwater shrimp.

Coenzyme Q10, as an antioxidant compound, has a role in the electron transport chain of the animal cell. To study the effects of this natural antioxidant on the quality and composition of the fish carcass; rainbow trout were fed by five dietary treatments containing 0, 25, 50, 100, and 200 mg/Kg of coenzyme Q10 during an 8-week feeding trial. The results showed that coenzyme Q10 increased the pH and decreased the peroxide value of carcass fish on the first day of keeping in the refrigerator. The carcass thiobarbituric acid index was not affected by coenzyme Q10 at different refrigerator storage times (P< 0.05). Dietary levels of coenzyme Q10 significantly improved the organoleptic properties of fish flesh. Feeding the fish with various diet levels of coenzyme Q10 elevated the total omega-3, eicosapentaenoic acid, docosahexaenoic acid, and long-chain polyunsaturated fatty acids in the carcass compared to the control group. Overall, the results of this study showed that using coenzyme Q10 in the levels of 100-200 mg/kg of diet improve rainbow trout carcass quality.

Marine fish cage culture is a fledgling industry in Iran. The continuous supply of juvenile fish is needed for cage farms, and it is the bottleneck of this industry. Therefore, selecting a suitable species for breeding and rearing that guarantees the stable supply of juvenile fish is the key to the continuity and success of this industry. To date, in Iran, several different species of marine fish have been introduced for breeding and rearing, however there have been various opinions among fisheries experts regarding target species selection. In this study, several indicators considered and categorized as principal factors affecting the target species selection, then the characteristics of fish used for breeding and rearing were compared with scientific evidence, and consequently, a species was nominated as the target one. Also, a native proper species for utilization in the marine aquaculture industry in Iran introduced.

In this study, the effect of immunostimulants nisin and lactoferrin on the growth and survival of Artemia fransiscana in challenge with Vibrio campbellii and Vibrio proteolitycus under gnotobiotic conditions was investigated. Artemia was kept and cultured in gnotobiotic conditions for five days, and then Artemia nauplii were fed with killed LVS3 bacteria (a strain of Aeromonas hydrophyla) at the number of 10.5 x 109 cells per Falcon tube every day. Also, lactoferrin and nisin were added to the falcons in the required amount on a daily basis. On the third day, the pathogens V. campbellii and V. proteolyitus were added at a concentration of 5 x 106 cells/ml. This experiment included six treatments, the treatment in which Artemia was fed only with killed bacteria was considered as the control treatment. Each treatment consisted of four repetitions, and on the sixth day, the survival rate, longitudinal growth of nauplii and the total biomass (biomass) produced were checked. Lactoferrin increased daily survival percentage, relative survival percentage and total biomass produced against Vibrio campbellii and Vibrio proteolitycus, but a significant difference was obtained only in total biomass produced (p<0.05). Nisin increased the daily survival percentage, relative survival percentage and total biomass produced against Vibrio campbellii and Vibrio proteolitycus, but a significant difference was obtained only in the total biomass produced (p<0.05). Also, there was a significant increase in the individual length of Artemia in lactoferrin treatment against Vibrio proteolyticus. In general, the results showed that the use of lactoferrin and nisin as immune stimulants can increase the total amount of biomass and increase the resistance of Artemia to Vibrio infection in gnotobiotic environment.

Shrimp sauce is a fermented product that is a condiment in Southeast Asian countries. This study aimed to produce a sauce from the frozen waste of Japanese shrimp (Macrobrachium nipponense) from the Anzali wetland, to evaluate it qualitatively, investigate its shelf life at refrigerator temperature (4°C), and assess the efficiency of sauce production in terms of economic use of shrimp waste. Experimental treatments consisted of pure sauce treated with salt (SPS), 0.5% sucralose (CSS), and cooked rice with 65% of the waste weight (CRS). The salt content ​​was the same in all treatments (1:1). Equal amounts of acetic acid, monosodium glutamate, and potassium sorbate were added to CSS and CRS treatments. Samples were then packaged in 250 mL glass vials, and refrigerated for six months. According to the results, there was no significant difference between chemical, microbial, sensory, nutritional parameters, and salt absorption factors (p≥5%). Whereas, chemical, microbial and sensory indices of all treatments were significantly different during storage (p≤5%). Coliform, Escherichia coli, Staphylococcus, Pseudomonas, mold, and yeast were not observed in the treatments. Sauce production efficiency in CRS, CSS, and SPS treatments was 64, 32, and 28%, respectively. Experimental treatments were of acceptable quality until the end of the period. However, considering that the sensory, microbial, chemical, and cooling time characteristics were not significantly different between experimental treatments, the two parameters of sauce efficiency and sauce volume were considerably different under CRS treatment. This could justify the use of cooked rice for the preparation of sauces from frozen shrimp residues. Nevertheless, considering the economic value and cost of rice, as well as the amount of sauce produced in the CSS treatment as opposed to the SPS treatment, making sauce from shrimp waste using sucralose or even pure salt could be justified.

Ichthyophthiriasis, which is also known as white spot or Ich, is caused by a parasitic ciliate called Ichthyophthirius multifiliis and it is one of the most important and common parasitic diseases. It may cause high mortality in large scale in ornamental and edible fresh water fish. To control this disease Malachite green, formalin, chloramine-T and other chemical compounds can be used, but each of these compounds may cause serious harm to human population and the environment. Therefore, introducing natural alternative compounds to use against this disease seems necessary. The aim of this study was to evaluate the alcoholic extract of Chelidonium majus L. in concentrations (0/1-6/4 gr/l) and exposure time of 1 to 3 hours on Ichthyophthirius multifiliis in vitro. The obtained data were statistically compared with the results obtained from the positive control sample (15 ppm formalin) and the control treatment. The results implicated that the mortality rate of parasitic teronts has a direct and significant relationship with increasing the concentration of the extract and the time of exposure and the mortality of the parasites increased significantly (p<0.05) with increasing the concentration of alcoholic extract from 0/1 to 6/4 gr/l. dosage 6/4 with 100% lethality had the best performance and is the most appropriate dose. There is no significant difference (p>0.05) between obtained data in comparison with formalin (control positive group), although the possibility of using this dose to treat live fish requires clinical examination.

The Maximum Entropy Model (MaxEnt) is a high-performance machine learning algorithm that is used to investigate the presence of species and to forecast the possible distribution of a target species according to its maximum entropy under different conditions and to determine the habitat suitability of species. In the present study, habitat suitability modeling for Nemipterus japonicus in the Makoran region (northern shores of the Makran Sea) was performed using the Maximum Entropy Model (MaxEnt). For this purpose, the data obtained from the fishing of Nemipterus japonicus during the period of 2015 to 2019 recorded by the Chabahar Offshore Fisheries Research Center in five areas were used to find points of presence. Based on the results obtained from the model, the variables of sea surface temperature at night and day and chlorophyll a concentration were recognized as the most important parameters in identifying the suitable areas, including the Gowatr bay area. Also, the area under the curve index (AUC) was equal to 0.998, which indicates the high accuracy and efficiency of the model in identifying the most suitable areas of Nemipterus japonicus distribution. The obtained results can be used as an effective tool for effective evaluation of conservation strategies for sustainable yield of Nemipterus japonicus fish stocks.

Seaweeds are ecologically important and have many applications economically. Inorganic carbon, nitrogen and phosphorus are the main elements needed for photosynthesis and growth of seaweed. Different concentrations of urea and phosphate as fertilizers with the ratio of 1:10 urea to phosphate (P: N = treatment one = 0.2: 2, treatment two = 0.4: 4, treatment three = 6: 0.6 and treatment four = 0.8: 8 mg/l) made treatments and compared to control (without nutrient, as fifth treatment), and their effects on growth of red macro algae, Hypnea musciformis were evaluated in triplicates. Algae sampled from the tidal area of the Oman Sea offshore at the time of the maximum tide and cultured to get optimum biomass for running the experiment. The algae were inoculated into experimental units and cultured for 45 days. A transparent plastic tank containing 40 liters of filtered seawater considered as the experimental unit. At the end of the experiment, the highest and lowest daily growth rate recorded in treatments 2 and control at the rates of 3.3±0.04 and 2.19 ± 0.02 g/day, respectively (p <0.05). These rates in third and fourth treatments were 2.87 ± 0.01 and 2.8 ± 0.01 g/day, respectively, and had a significant increase on growth of algae in comparison to the control (p <0.05). The results indicated that the concentrations of urea and phosphate rates and their ratios in the medium affecting on growth of this alga under outdoor conditions, and at the concentration of 0.4: 4 mg/l and ratio of 1/10 of phosphate to urea algae had the highest growth.

The aim of the present study was to investigate the effect of replacing biosilage from chicken intestine with fish meal in the diet on serum indices, muscle quality and digestive system bacterial flora of Rainbow trout (Raised in two farms of Karkandeh village with well water and dam farm with river water-Sari city). For this purpose, after producing biosilage from the waste, diets containing 50 and 100% biosilage were prepared and the findings were evaluated along with the control. The results of serum indices in both farms showed an increase in total protein, IgM and lysozyme in 100% treatment, and 50% and control treatments were in the next order (p<0.05). The amount of albumin in the fishes of Karkandeh village was not significantly different between the treatments (p>0.05), but in the dam fishes, the highest amount was recorded in the 100% biosilage treatment (p<0.05). The amount of free oxygen radicals in the fishes of Karkandeh village in the control treatment was more than the two treatments containing biosilage (p<0.05), but in the dam fishes, the highest level of the mentioned index was reported in the 100% treatment (p<0.05). The results of carcass qualitative analysis showed that in both farms the amount of protein and ash in the treatment containing 50% of biosilage was higher than other treatments (p<0.05). But the amount of fat in the mentioned treatment was less than the others (p<0.05). In the study of bacterial flora of fish gastrointestinal tract, it was found that the population of aerobic and lacticacid bacteria was significantly higher in 50% biosilage treatment than the other two treatments, and 100% and control treatments were in the next rank, respectively (p<0.05). According to the findings, the use of biosilage is a desirable alternative to fish meal in the Rainbow trout diet and helps to improve serum indices, muscle quality and bacterial flora of the gastrointestinal tract.

A study carried out for reduction of fish meal in Beluga Huso huso diet. A basic diet based on 54% fish meal were formulated. A mixture based on corn gluten wheat and anchovy fish meal formulated similar to amino acid profile of basic diet at the levels of 20, 40, 60 and 80% as experimental treatments, fish meal (FM) (Basal diet) and corn gluten meal base included 20% replacement (CGM20), 40% replacement (CGM40), 60% replacement (CGM60) and 80% replacement (CGM80) with Similar protein (44%), energy (18 MJ / kg) and amino acid profiles. Beluga fish (Huso huso) with average weight of 167.6± 6.5g introduced in each experimental unit and were fed on experimental diets during a 10 –week culture period. Effect of these alternatives on growth indicators and liver tissue were investigated. Alternative food had no effect on fish growth indices and there was no significant difference in fish performance growth (P>0.05). No significant difference was observed in hepatosomatic index (P>0.05). Liver tissue was normal in fish fed FM, CGM20, CGM40, CGM60 and a low damage observed in liver tissue such as cell necrosis, nuclear hypertrophy and hemorrhage. But, fish liver tissue fed by CGM80 had higher abnormal liver damages such as lipid degeneration, cell necrosis, biliary stagnation and hemorrhage.