JOURNAL OF FISHERIES SCIENCE AND TECHNOLOGY (JFST)
Year:2015 | Volume:4 | Issue:1|Papers Count:10

The effect of four light intensities (0, 100, 2000 and 5000 lux) on some reproductive charachteristics of Artemia urmiana brood stocks was investigated. 30 male and female individuals were reared in 3 liter containers until the death of all females over the consecutive weeks. Results showed significant differences in terms of average weekly offspring productions among the treatments. The broodstocks cultured in 5000 lux had an increasing trend in offspring production from the first to the fifth week, but a decreasing trend from the sixth to the tenth week. A relatively similar situation was observed in the 2000 lux treatment. The broodstocks cultured in 0 and 100 lux intensities had reduction fluctuations in offspring production from the first to the sixth and seventh weeks, respectively. The highest percentages of egg-sac females were observed in the early and mid-raising weeks, showing the maximum in the mid-week (until the fifth week) in all treatments. In most weeks, a considerable increase was detected in the encysted embryos production in the broodstocks reared in 0 and 100 lux intensities as compared with 2000 and 5000 lux intensities. The survival percentage of broodstocks at the end of the fifth week was 95, 86, 23 and 30 % (in order from high to low levels of light intensities).Considering the increased production of offspring and higher survival rate in the broodstocks as well as the increase in egg-sacsfemales (during the first five weeks), it is recommended that the light intensity of 5000 lux is useful for the mass culture of A. urmianain hatchery reared broodstock.

The effects of cooking methods on sensory attributes and physical properties (firmness, normal shear, cooking loss and color based on L*, a* and b*) of rainbow trout (Oncorhynchus mykiss) fillet was investigated. The study was based on application of autoclavingat 120oC for 5 and 10 minutes, deep frying of the flour coated fillet at 180oC for 2 and 5 minutes and microwaving at 600 watt for 2, 4 and 6 minutes. Cooking loss significantly differed among the cooking methods, the highest of which occurred in 6 minute microwaved treatment. The highest and the least color changes were, respectively, recorded in coated fillet fried for 5 minute and for 2 minute microwaved fillet treatment. In terms of normal shear results, control and 2 minute fried fillet treatment had the hardest tissue, respectively. Also the penetrate tests revealed a significant difference between control and other treatments (p< 0.05) as the hardest tissue was the one that fried for 5 minute and the softest one was the control. However, the highest score was allocated to the fried and 6 minute microwaved treatments by the panelists. Based on the sensory evaluation, fillet fried for 5 minute was found as a preferred cooking method.

The effect of simultaneous application of probiotic and digestive enzyme on the intestinal digestive activity of the white leg shrimp, Litopenaeus vannamei, was evaluated. For this purpose, the juvenile shrimps were fed for 30 days with a dietary probio-enzyme (containing a combination of six exogenous enzymes and four probiotic bacterial strains) at four concentrations of 0, 0.25, 0.5, and 1 g kg-1 feed. Shrimps (5.04±0.39 g ind-1) were randomly distributed in 12 aquaria (4 treatments ´ 3 replications); each aquarium contained 15 individual shrimps. Results indicated significantly (p£0.05) higher growth performance, amylase and lipase activity at 0.5 g kg-1 treatment as compared to other treatments. Protease activity was, however, significantly (p£ 0.05) higher at 1.0 g kg-1 treatment as compared to other groups. Results also indicated that increase in the concentration of probiotic and enzymes supplementation was not associated with increase in all the digestive enzyme activity. In other words, probiotics and enzymes only within specific range can have positive effect on growth performance and digestive enzyme activity of L. vannamei, above or below.

The present study was to evaluate the impact of feeding level and fish size on the growth factors,carcass composition and digestibility of rainbow trout. Six experimental treatments were assigned by the use of three feeding levels (maintenance, medium and satiation levels) and two fish sizes (43.02 ± 2.93 and 231.32±6.74g) according to a 3´2 factorial design. There were three replicates for each treatment and the experiment lasted for 59 days. The results showed that there is a significant interaction effect between fish size and feeding level for body weight gain, final body weight and specific growth (p<0.05). Body composition (dry matter, energy, moisture, fat and protein) was affected by feeding level and size of the fish (p<0.05). However, the interaction effect between fish size and feeding level for body composition was not significant (p>0.05).The digestibility measurements showed that fish size and feeding level changed significantly digestibility of protein, lipid, energy and dry matter in rainbow trout (p<0.05). Maximum growth at satiation feeding level can reduce feed conversion ratio and increase waste production at both fish sizes.

The chemical-morphological relationships in rainbow trout, Oncorhynchus mykiss, was assessed through photography in light room. The image data were transferred to a laptop and analyzed by MATLAB (Matrix Laboratory) version R2009a. The designated algorithm of 7 features, including length, height, area, perimeter, equivalent diameter, major and minor axis length were extracted from the images. Afterward, chemical compositions of the fish (including crude protein, crude fat, moisture content, pH value and leakage), were determined. Pearson's correlation coefficient was used to correlate visual and chemical properties. Factors were assayed with linear, logarithmic, exponential and power method. Results showed that pH, leakage, protein and fat had a good correlation with fish length, and moisture with fish perimeter, in Quadratic equation (R2= 0.993, 0.991, 0.991, 0.989 and 0.992, respectively). In conclusion, this methodology can be applied for automated chemical analysis and on-line monitoring in fish farms.

The effect of partial replacement of NaCl by KCl on sensory and microbial properties of hot smoked kilka (Clupeonella cultriventris caspia) during storage in refrigerator was investigated in two stages. Samples were initially prepared and, in the first stage, were exposed to brine solution with 15% mixture of NaCl/KCl at 5 different levels (NaCl 100%, control; NaCl/KCl 75.25 %, treatment A; NaCl/KCl (50.50%, treatment B; NaCl/KCl 25.75%, treatment C; KCl 100%, treatment D) for 3 hrs. The smoking process included turning the samples into drying and hot smokes by slow and high rates of Atmos set. All samples were tested by sensory analysis and salt intake to select the nominated treatments. In the second stage, sensory and microbial properties of selected treatment were compared with the control samples during storage in refrigerator for 15 days. Microbial tests revealed significantly greater rate of mold contamination in treatment A (25.75% KCl/NaCl) than the control (100% NaCl) in the early days, but reduced later in both. The sensory analysis indicated no significant difference between the two treatments. According to the results, sodium chloride could be replaced up to 25%with potassium chloride for hot-smoked kilka without negative effects on microbial and sensory properties.

Oxidative stability of oils, fats and fatty food products can be affected by many factors such as oxygen, light, heat, metal ions and enzymes used and finally it brings about oxidative corruption. This study has been done to survey the role of Dorema aucheri extract in oxidative stability of fish oil (under microwave heating) and comparising that with BHT synthetic antioxidant. Concentrations of 250 and 500 ppm extracts of Dorema auchri and BHT 200 ppm were added to fish oil and a fish oil sample without the addition of antioxidant was considered as control, Then they were sampled after putting in microwave at time periods 0, 3, 6, 9, and 12 minutes. Chemical oxidative indicators (peroxide, free fatty acids and thiobarbituric acid) were surveyed. According to the results, in all times putting in microwave the amount of peroxide, free fatty acids and thiobarbituric acid in the treatments that contained extract, were lower than the control treatment, but were higher than the treatment that contained BHT. A significant difference wasn't seen among the treatment that contained 250 ppm of extract and the treatment that contained BHT (p>0.05). According to the results, because of significant difference of samples contained extract with control sample and the lack of significant difference sample containd 250 ppm extract with BHT, it would be expected that Dorema aucheri extract as antioxidant can be used in food industry in maintenace of fish oil.

Fish egg is an important source of polyunsaturated fatty acids, protein, minerals and vitamins. These are produced in the form of smoked, salted and then consumed. Initial preparations for washing eggs can have an important role on the finished product. To increase the strength of the egg membrane, waste removal, connective tissue and broken shells, fish eggs obtained after washing with different methods are carried out. In this study, three treatments have been utilized including, non-boiled water, boiled water cooled to3 to 5oC, boiled water to 40oC. Afterward, the two groups were prepared with 1.5% salt and no salt. Results of chemical, microbial and sensory tests were assessed on days 0, 12 and 24. It was shown that, cooled boiled water with a temperature of 3 to 5oC with 1.5% salt and boiled water with a temperature of 40oC with 1.5% salt gave the best and Non-boiled water with ambient temperature devoid of salt had the worst chemical and microbial results. In addition, cold boiled water with temperatures 3 to 5oC with 1.5% salt showed the best sensorial results. Boiled water with a temperature of 40oC and non-boiled water without salt had the lowest sensorial results.

The toxicity of cypermethrin at 0.02 mg L-1 concentration in relation to salinity (0 and 14 ppt) and temperature (16±1 and 25±1oC) was studied on the liver tissue of zebra fish (Aphanius sophiae) exposed to cypermethrin for 14 days under labratory condition. The liver tissue changed significantly with changes in salinity and temperature. The major changes were overlapped hepatocytes, nucleous irregularity, cloudy swelling, atrophy, fat degeneration, pyknosis, focal necrosis, karyolysis, accumulation of kupffer cell, necrosis and bile stagnation. The results showed that sensitivity to cypermethrin increased with decrease in salinity and increase in temperature. This fish is, therefore, not a suitable indicator for cypermethrin assessment in aquatic ecosystems, and if considered as an indicator, the temperature and salinity should also be considered.

Radula as the main feeding organ in gastropods not only functions in obtaining food, but also considered as an important organ in classification and phylogenic studies. In this research, the radula morphology of the two species, Conomurex persicus (Strombidae) and Mauritia grayana (Cypraeidae) from BandareLengeh and the Larak Island were analyzed. The collected samples were fixed in 70% alcohol, and radulae were isolated and processed in the laboratory, then photographed with a scanning electron microscope (SEM). Radula in these two species is of taenioglossan type with 7 teeth per row, but structure of radula teeth in two species are different from each other. Due to various type of feeding habits in C. expersicus and M. grayana, they require radulae with structure to suit their needs. On other hand, any radula structure can also imply special dietary habit, so it can be used to understand the feeding habit of a particular gastropod species.