نشریه علوم و فنون شیلات
سال چهارم شماره 4 (پیاپی 13، زمستان 1394)

The effect of three probiotics (Lactobacillus plantarum, L. casei and Bacillus subtilis) on growth and survival of artemia against a pathogenic bacteria, Vibrio campbellii, in gnotobiotic conditions were investigated. A total of 1560 nauplii were equally transferred to 78 falcon tube containing 30 ml of autoclaved sea water with 70 ppt salinity. Treatments consisted of a control (alga, Dunaliella tertiolecta) and 12 treatments of 3 bacteria (each with 25%, 50%, 75%, and 100% replacement) and each treatment was done in 6 replicates. On the sixth day, survival rate, length and the number of bacterial colonies in the nauplius were studied. Also, in this day the nauplius was challenged with the pathogenic bacteria, V. campbellii. The maximum length of the nauplius was observed in the group supplied with 25% L. plantarum and 75% of alga (P

The effects of frozen storage (-20°C) of silver carp (Hypophthalmichthys molitrix) for periods of 0 (control), 2, 4 and 6 months on the qualitative properties of surimi powder was investigated. Qualitative characteristics were assessed through analysis of proximate composition, sensory evaluation, color changes, density, oil adsorption capacity, water holding capacity, protein solubility, emulsifying capacity, emulsion stability, foam capacity and stability, gel forming ability, and thiobarbituric acid value. Most of the qualitative indices decreased significantly (p

The present study investigateeffect of different dietary macronutrient composition on fatty acids profile, body fat and pancreatic lipase enzyme activity in Siberian sturgeon. A group of 180 Siberian sturgeons juvenile (initial weight, 30 ± 5 g) were used in this experiment and fed on four isoenergetic diets. Diets were named LP-St (low protein and high carbohydrate: lipid ratio), HP-St (high protein and high carbohydrate: lipid ratio), LP-L (low protein and low carbohydrate: lipid ratio) and HP-L (high protein and low carbohydrate: lipid ratio). Fish were fed apparent satiety for 10 weeks. The samples were obtained from body carcass and juveniles intestine. In this study, the same level of fish oil and sunflower oil were used as a source of diet lipid content. The HUFAs content in HP-St and LP-L diets were showed highest and lowest value, respectively. The results showed the body fatty acidsprofiles was significantly affected by fatty acids composition in diets (P

The effect of metal ions, surfactant, oxidizing agents and enzyme inhibitors was considered on trypsin and chymotrypsin activity of the Caspian brown trout fry. The results showed K and Na didn’t significanly decrease trypsin and chymotrypsin activity (p>0.05). Ca2 and Mg2 significantly increased trypsin and chymotrypsin activity (p0.05). Oxidizing agents, including hydrogen peroxide and sodium perborate, significantly decreased trypsin (p0.05). The inhibitors such as TPCK, pepstatinA, iodoacetic acid, EDTA and ß-mercaptoethanol did not significantly decrease the trypsin activity (p>0.05), but they significantly decreased chymotrypsin activity (p0.05).

The life cycle of bobtail squid (Euprymnahyllebergi:Sepiolidae) was investigated by incubating its eggs and rearing the hatchlings at 28.5±0.5°C and 37-38ppt salinity conditions in the Molluscs Research Station (Bandar Lengeh). After 12±3 days incubation, hatchlings with 2.23±0.05 mm mantle length and 4±1 mg wet weight emerged out. Hatchlings were fed with artemia, mysid shrimp and postlarvae of white-leg shrimp. In 30 days, they grew to 5.94±1.18 mm and 254±16 g, in 60 days to 13.96±1.87 mm, and 2.214±0.213 g, and in 90 days they grew to 18.14±2.23 mm and 4.234±0.548 g. First mating and spawning was observed in days 109 and 110, respectively, when the squids were 20.12±2.64 mm in mantle length and 5.849±1.204 g in body weight. Each female laid 70±10 eggs and died 2-4 days after spawning, followed by males after 7-15 days. Results show that bobtail squid have short life span and can easily be produced and succeeded by the next generation under laboratory conditions.

The genetic structure, diversity and population kinship of four strains of ornamental barb, Puntius tetrazona, viz. tiger, green, albino and rose barb, was studied through microsatellite markers. Genomic DNA was extracted from dorsal fin tissue of 160 individuals (40 per strain) using kit and its protocol from Denazist Co. PCR amplification was performed using four pairs of microsatellite primers (Sm17, Sm25, Ma106 and Ma109). PCR products were electrophoresed on 8% acrylamide gel and stained with silver nitrate. The results showed that all loci were polymorphic. A total of 21 alleles for four markers in four strains was found. The mean number of alleles per locus at the population level was 5.25, and the number of alleles per polymorphic locus varied between 3 and 6. Average number of the observed alleles in tiger, green, albino and rose barb strains were 3.25, 3.25, 4 and 3.25, respectively. The observed and expected heterozygosity averages were 0.24 and 0.49, respectively. Most cases significantly deviated from Hardy-Weinberg equilibrium (p≤0.01). The analyses of molecular variance showed high genetic diversity (97%) within populations. The Fst value was 0.03 which indicates the low genetic differentiation between populations. UPGMA cluster analysis based on Nei genetic distance showed two different populations inhabiting the regions. Therefore, the microsatellite markers used in this study were found suitable for the different strains, and the degree of diversity was very low between strains, indicating a high degree of kinship.

Carboxymethyl cellulose (CMC) and tragacanth gums at 0.5 and 1% levels % were added to the fish balls from silver carp to improve the its texture and sensory characteristics. The proximate composition, physical factors (batter pick-up, product yield, shrinkage and oil absorption reduction), sensory analysis and textural properties of fried balls were compared with the control treatment. All treatments showed less fat and oil absorption rate (p> 0.05) compared to the control treatment. Treatment containing 1% tragacanth gum showed the highest levels of wet, lightness, hardness and springiness, while treatment containing 1% CMC showed the highest product yield and lowest amounts of expressible water, fat, lightness, oil absorption and springiness (p>0.05). Overall, the performance of tragacanth gum on the texture characteristics was more desirable than CMC gum. All textural index decreased in treatments containing 1% gum. Hence, the use of low levels of the gums is recommended.

The effect of ozonized ice on shelf-life of Indian mackerel (Rastrelliger kanagurta) muscle was studied during 16 days storage period, based on chemical and microbial assessments. Chemical analysis (pH, total volatile nitrogen bases, peroxide, trimethylamine) and microbial analysis (total bacterial load and psychrophillic bacteria) was done every four days. The lowest pH, TVB-N and TMA values were observed in the ozonized ice treatment, while its PV value was higher. The ozonized ice effectively reduced the total viable count (TVC) and psychrophillic bacterial count (PTC) by 2.22 and 2.07 log10 CFU cm-2, respectively, at 12 days period. Thus, the ozonized ice protected fish quality better than the control treatment until the end of storage.

The fatty acid composition and changes in silver carp fillet after flash frying, frozen storage and deep frying of was studied. For this purpose, fillets with edible coating and uncoated were tested. Fillets after flash frying for 30s, cooling, packaging and cooling were kept in freezer for three months, then deep fried. Flash frying and final deep frying increased the amount of total fat in fillets. The fat content of samples (5.07% at day 0) changed to 9.52 ± 1.97 and 7.54 ± 2.80 % after flash frying and to 9.33 ± 0.70 and 9.39 ± 0.24 % after final deep frying in uncoated and coated samples, respectively. Moisture content decreased after frying and increased after 3 months frozen storage (P

The effects of starvation periods on physiological response of the juvenile Persian sturgeon, Acipencer persicus, was assessed through such stress factors as glucose, cortisol and hepatic enzymes for a period of 8 weeks. For this purpose, in a randomly designed experiment, five groups of fish (108.04 ± 0.28 gr) in 3 replicates were starved for a period of 0 (control), 1, 2, 3 and 4 weeks and fed them to satiation after their starvation lags. Blood plasma glucose and cortisol during starvation periods did not significantly change (p>0.05). This indicates high performance of this specific in maintenance of blood glucose during starvation and recovery of glucose level after feeding. However, plasma hepatic enzymes level in fasting treatments increased (p