مجله علمی شیلات ایران
سال سی‌ام شماره 6 (پیاپی 128، بهمن و اسفند 1400)

The present study was conducted to evaluate of different levels of locust meal (Schistocerca gregaria) on growth function, survival, biochemical composition and intestinal digestive enzymes in rainbow trout fingerling. Four experimental diets with different replacement levels of 0 (control treatment), 15 (SG15), 30 (SG30) and 60% (SG60) of fish meal with locust meal were formulated with equal protein (46.5%) energy (4652 kcal) contents. Diets were distributed in a completely randomized design in four treatment and each with three replications and the average initial weight (5.08±0.33) in 12 tanks for eight weeks (25 pieces of fish in each tank) and Feeding was done three times a day to satiety. Physicochemical parameters such as temperature (17.3°C), dissolved oxygen (6.49 mg), pH (7.55) were constant during the experiment. The results revealed that the highest final weight was observed in 30% treatment (89.34±20.616 %) and differences between 0, 15 and 60% treatments (p<0.05). In 60% treatment, a significant decrease in growth indices and nutritional efficiency was observed (p<0.05). Also, the amounts of protein, fat and moisture in the body of fish were significantly different compared to the control treatment (p>0.05). Analysis of digestive enzymes showed that the highest activity of protease and amylase enzymes was observed in fish fed SG30 diet. The results of this study showed that using 30% locust meal instead of fish meal can improve growth performance, the biochemical composition and digestive enzymes rainbow trout fingerlings.

The occurrence of puberty usually slows down the body's growth rate because the energy from the food is diverted to gonadal development instead of muscle production. By producing sterile fish, these problems can be solved. One method of sterilization is through ploidy induction (especially triploid). Given that these triploid fish are stressed in the early stages of life, it is important to be aware of their ability to withstand the rearing environment's stressful conditions and assess the rate of growth, survival and deformity caused by shock. 3 treatments were considered for the triploidy inducing in this study. In treatment A, the eggs were placed in water at 27° C for 15 minutes after fertilization for 30 minutes. In treatment B, shock was performed 20 minutes after fertilization for 20 minutes at 26° C and in treatment C, shock 40 minutes after fertilization was performed for 10 minutes at 28° C. A treatment with 13,200 eggs was considered as Control Group (D). The efficiency of triploid induction was 84% in treatment A, 76% in treatment B and 98% in treatment C. The results of 10 stages of juvenile growth study did not show a significant difference until 208 days after hatching (p≥0.05). The fish survival of the treatments was examined in 7 separate stages. In total, the survival of treatment A was 66%, the survival of treatment B was 81%, the survival of treatment C was 72% and the survival of Control group was 86%. Also, the number of larvae with deformity and appearance defects from the hatching stage to the beginning of active swimming and reaching a weight of 200 mg were examined quantitatively and qualitatively. In total, the malformation rate in treatment A was equal to 6.51%, in treatment B was equal to 7.65%, in treatment C was 10.75% and in Control group was 0.6% (p<0.05).

Haraz River has an important role in the development of aquaculture and the production of rainbow trout in Mazandaran province. Since 2015, the production of rainbow trout has been decreased in the farms along the river and almost halved. This study have been investigated the microbial indices and heavy metals in water as well as the identification of common bacterial pathogens and their resistance to antibiotics and used them as effective factors in the fish health and production. This study was conducted during four seasons (summer, autumn and winter 2017 and spring 2018) in 6 rainbow trout farms along the Haraz River. The results showed that the amount of the water mercury in all seasons was from minimum 2 to maximum 12 times the allowable limit but the arsenic level was standard in all sampling times. The most important clinical symptoms were observed in the fish including fin rot, erratic swimming, inflammation and hyperemia of the liver and kidneys. From 420 fish with clinical signs, 12.15% and 87.85% of fish were positive and negative bacterial culture respectively. The all of bacterial isolates were gram-negative and no gram-positive bacteria were isolated. The bacterial agents identified were including, Yersinia (37.25%), Aeromonas (33.35%), Eduardzilla (11.76%), Vibrio (7.84%), Pasteurella (5.88%) and Citrobacter (3.92%). The highest and lowest antibiotic resistances were found against amoxicillin and trimethoprim sulfamethoxazole respectively. In evaluation of the microbial water indices including total bacterial count, coliform count, fecal coliform count and E. coli, the results showed that the all of microbial indices were not allowable level in the most of the sampling time.

In this study, three protein hydrolysates were produced from muscle, fishmeal and fishmeal effluents (stickwater) of Anchovy Kilka fish (Clupeonella engrauliformis) using Alcalase (temperature=50ºC, pH=8.5, time=2 h) and their proximate compositions and amino acids profiles were analyzed. Based on the results, the highest protein content (81.97%) was in KMH and the lowest lipid (0.51%) and protein (70.31%) contents and the maximum ash (22.64%) were in SWH. The highest degree of hydrolysis was observed in SWH (17.23). KMH and FMH were rich in aspartic acid, glutamic acid and lysine while SWH was rich in glutamic acid, glycine and alanine. KMH had the highest content of hydrophobic and aromatic amino acids (p<0.05). SWH was the only treatment containing ornithine (1.44%). The results of amino acid profiles of hydrolysates and their calculated chemical scores showed that KMH and FMH were rich in the essential amino acids and met the nutritional needs to support optimal growth of human, common carp, rainbow trout, Nile tilapia and monodon shrimp. However, SWH could only meet the amino acid requirements of rainbow trout and the limiting amino acids for other species were methionine, threonine, arginine and isoleucine. Due to The high nutritional values and amino acid composition of KMH and FMH, they could be used as health promoting protein supplements. Also, the SWH composition showed that this effluent could be used for developing value-added products.

In this study, the effect of different concentrations of three gas mixtures (carbon dioxide, nitrogen, oxygen), as well as vacuum conditions, and ordinary packagings in 3 types  of flexible 4-layer films, containing fennel essential oil were evaluated for extending shelf life of fresh rainbow trout fish at 40C. Ordinary conditions as control samples, were compared with four kinds of modified atmosphere packaging 1)75% CO2+25% N2, 2) 25% CO2+75% N2, 3)% 48CO2+48% N2+4% O2 and 4) under vacuum condition, along with injection fennel essential oil(2% WE/Ws), and samples without essential oil. Fish samples were packaged in different flexible multi-layer films, PET12/AL7/OPP20/‌‌LLD90, PET12/AL7/PET 12/LLD100 ‌‌, and PET12/AL7/PA15/‌‌LLD90, under MAP. The microbial aerobics and anaerobic counts and the pH changes, determination of peroxide content, total volatile nitrogen, and sensory properties of samples were performed on the packaged samples at different 5, 10, 15, 20 days. The experiments revealed that the gas composition of 75% CO2 combined with fennel essential oil due to high antimicrobial properties of these factors, and 4-layer PET12/AL7 /PA15/ LLD 90)123 μ) ‌‌‌‌along with poly amid as a low water vapor transmission rate containers in spite of less thickness, were used to maintain the long-term of (20 days) fresh trout fish and had a desire effect on controlling microbial growth and chemical properties, and sensory evaluation of samples(odor, color, texture, appearance, and taste) were observed better.

The aim of this study was to evaluate the different properties of bioactive peptides encapsulated with a combined coating of nanoliposome and chitosan. Therefore, the wastes of shrimp processing and packaging centers were hydrolyzed using Neuterase enzyme and the antibacterial, antioxidant and antihypertensive properties of the product were evaluated in the form of five treatments of P (free peptides), NP (peptide-carrying nanoliposomes), NP-CH-0.05 (peptide-carrying nanoliposomes with a coating of 0.05% chitosan), NP-CH-0.1 (peptide-carrying nanoliposomes with a coating of 0.1% chitosan) and NP-CH-0.5 (peptide-carrying nanoliposomes with a coating of 0.5% chitosan). The results showed that all research treatments have certain antibacterial, antioxidant and antihypertensive properties. P and NP treatments provided almost equal values for all three properties and their properties did not differ significantly (p>0.05). Chitosan-coated treatments had significantly more antibacterial, antioxidant and antihypertensive properties than P and NP treatments (p<0.05). In chitosan-coated treatments, with increasing the amount of chitosan in the coating, all three mentioned properties were significantly increased (p<0.05). The highest growth inhibition activity of Escherichia coli, Bacillus cereus and Staphylococcus aureus (45.89±0.96, 34.82±0.75 and 49.67±1.45%, respectively), the maximum amount of inhibition of DPPH, ABTS and linoleic acid peroxidation (63.52±2.86, 73.91±0.29 and 89.06±2.11%, respectively) and also the most effective antihypertensive property (37.91±1.29%) were related to NP-CH-0.5 treatment.

The presence of microplastics (less than 5 mm) in marine environments, owing to their persistence and risk imposed to marine communities has become a growing global concern. Considering the hazardous nature of microplastic particles to benthic communities and commercial species of the Caspian Sea, the study was conducted to investigate the distribution of microplastics in sediments of the southern shores of the Caspian Sea. Sediment samples were taken by a Van Ween grab as sampling sites located in Astara, Bandar Anzali, Kiashahr, Rudsar, Sari and Turkmen port during the winter 2018. Sari station with an average of (340±20 items/kg dry sediment) had the highest and Turkmen port station with (156.66±75.71 items/kg dry sediment) had the lowest microplastic frequency. The size of the microplastics varied from 0.2-9.2 mm and most of the microplastics found (35.54%) were 1-2 mm in size. The extracted microplastics were mainly filamentous although fragment microplastics and films were also observed. In the studied samples, high color diversity was observed and blue (63.85%) and brown (20.31%) had the highest frequency. Using ATR-FTIR analysis, 4 types of polymers including cellophane, polyethylene, polypropylene and polyvinyl acetate were identified. The most abundant microplastics identified were cellophane. This study is among very few studies on microplastic contamination in the sediments of the southern Caspian Sea and the obtained results vital for further studies.

In this experiment, effect of micronutrient supplements of selenium nanoparticles, vitamin C and E supplemented to the diet at levels (0.1, 30 and 100 mg / kg: diet A), (0.2, 60 and 200 mg / kg: diet B), (0.3, 90 and 300 mg / kg: diet C) and control diet (no supplement: diet D) on Growth indices, food efficiency, immune system and liver enzymes of juvenile Huso huso were examined. A total of 120 Huso huso with an average initial weight of 77.34 ± 1.38 g for 10 weeks were randomly tested in 4 treatments (each with 3 replications) for 70 days. Final weight, body weight gain percentage, specific growth rate, daily growth and protein efficiency ratio in fish fed B diet (0.2, 60 and 200 mg / kg selenium nanoparticles, vitamins C and E) were significantly higher than the control diet. (P <0.05). The activity of aspartate aminotransferase (SGOT) and alanine aminotransferase (SGPT) enzymes was higher than that of fish fed the control diet. (P <0.05).significant difference was observed in the level of total immunoglobulin (Ig) of fish fed diets B, C and control (P> 0.05),but level of ACH50 in fish fed control diets was significantly higher than diets A and B (P <0.05) and There was no significant difference in lysozyme content in control fish, A and B (P> 0.05). The results of this study showed that adding 0.2, 60 and 200 mg / kg selenium nanoparticles, vitamins C and E to the commercial diet could significantly increase of final weight and growth indices, but more studies should be done on the effect of microcoated selenium nanoparticles on performance. Liver and immune system characteristics of this species.

In this study, growth, biomass, concentration of chlorophyll a chlorophyll b, and carotenoid content of Dunaliella salina were evaluated in five different treatment (including: T1: 35 ppt (freshwater + salt), T2: 20 ppt (freshwater + salt), T3: 35 ppt (deep aquifer well water+ salt), T4: 35 ppt (concentrated deep aquifer well water), and T5: 20 ppt (deep aquifer well water)) in the same conditions, including the amount of light intensity (33.75 μmol.m2.s1) Photoperiodic lighting (16 hours of light:8 hours of dark), the temperature at (25±1 degrees centigrade), pH (8), cultivation medium (modified Johnson medium), and the same 24-hour aeration for 24 days. The results showed that among different treatments, the lowest pH fluctuation was observed in the T3, T4, and T5. In addition, T3, T4, and T5 had a better situation in terms of growth, and growth rate was increased until the 21st day of the experiment. Maximum cellular yield (R) for T3, T4, and T5 was recorded on day 21, which was 9 days longer than other groups (T1 & T2). The Minimum cell number, minimum optical density (OD), minimum specific growth rate (SGR), minimum doubling time (DT), minimum dry biomass, and maximum Division per day (k) were recorded for T2. The maximum dry biomass was observed in T4. The highest and lowest mean of chlorophyll a concentration appeared in T4 and T2, respectively. While the maximum and minimum mean of chlorophyll b level was recorded in T2 and T1, respectively. The highest and lowest mean of carotenoids concentration was obtained in T1 and T2, respectively. Based on the results of this study, the cultivation of D.salina with deep aquifer well water is possible.

This study aimed to determine the possibility of producing dietary spread using farmed silver carp skin gelatin and pectin to compare the effect of different concentrations of gelatin and pectin on the physicochemical and microbial changes of the low-fat spread at refrigerated storage. Six treatments were produced with different concentrations and ratios of the fish gelatin and pectin. The physicochemical and microbiological tests included acidity, pH, total bacterial counts, psychrophilic bacteria, Staphylococcus aureus, and mold and yeast were measured to determine the shelf life at refrigerator temperature. The acidity and pH did not show significant differences between different treatments. The experimental treatments had acceptable color and microbial properties for 4 weeks. The acidity and microbial properties did not show significant differences between experimental treatments. No significant differences were observed between the experimental treatments in terms of color. The results showed that the acidic gelatin extracted from silver carp skin, in combination with pectin, enables the possibility of producing a dietary spread. It is recommended to produce a low-fat spread using 4% of the fish gelatin and pectin in equal proportions.