نشریه علوم و فنون شیلات
سال هفتم شماره 3 (پیاپی 23، تابستان 1397)

As a polycation polysaccharide, chitosan is produced by deacetylation of chitin. Chitosan is a non-toxic, decomposable, and biocompatible substance that has antimicrobial properties. The aim of this study was to investigate the effect of chitosan coating and Piper nigrum essential oil on shelf life of grass carp in modified atmosphere packaging (MAP) at the refrigerator temperature (4°C). In this experimental study, Piper nigrum and grass carp were used. After immersion of the samples into Piper nigrum and chitosan essential oil, samples were packed with MAP. The treatments consisted of control treatment (no coating and essential oil), first treatment (0.1% essential oil), second treatment (0.5% essential oil), and third treatment (1% essential oil of Piper nigrum with chitosan coating). The chemical parameters, including peroxide value (PV), thiobarbituric acid (TBA), total volatile basic nitrogen (TVB-N), free fatty acid (FFA) and pH and total viable count (TVC) of mesophilic bacteria were evaluated at the intervals of days 0, 3, 6, 9, 12, and 15. Two-way ANOVA and least significant difference (LSD) tests were used. Findings: Changes of pH and FFA progressively increased during the time of storage for all treatments. In all treatment, the level of PV did not exceed higher than the level of limit (mEq/kg). The lowest changes of TBA and TVB-N were related to 1% treatment of P. nigrum essential oil that were significant different with other treatments (p<0.05). TVC of the samples was significantly between treatments during storage (p<0.05). The use of chitosan coating and 1% of Piper nigrum essential oil increases shelf life of grass carp fillet at refrigerator temperature to 9 days.

In this study, the effect of dietary macronutrient composition (two levels of protein 44% and 38% with two carbohydrate/fatty ratios of 1.4 and 3) was studied during starvation and re-feeding with the aim of achieving growth, body composition, and fatty acids in the body of Siberian Sturgeon (Acipenser baerii, Brandt, 1869). This experimental study was carried out at the International sturgeon research institute in a completely randomized design. 360 fish (with an initial weight of 30±5g) were randomly distributed in 24 tanks of 500 liters (15 fish per tank) with a volume of 350-400 liters capacity. Fish were fed on 4 different diets; protein 38% - carbohydrate: lipid ratio 3 (LP-St), protein 44% - carbohydrate: lipid ratio 3 (HP-St), protein 38% - carbohydrate: lipid ratio 1.4 (LP-L) and protein 44% - carbohydrate: lipid ratio 1.4 (HP-L), respectively. The fish were fed apparent satiation for 3 weeks, then, starved for two weeks, and, then, re-fed for 5 weeks. The results were analyzed, using SPSS 22 software by multivariate analysis of variance and Duncan's test. Findings: Compensatory growth did not occur in any treatments. In the control group, the best growth was observed in HP-L, while after re-feeding, HP-St represented the best weight gain and feed conversion ratio The dietary composition has a significant effect on the SFA, MUFA, and PUFA fatty acids, while the two weeks of starvation slightly increase only MUFA and have no significant effect on other fatty acids.

Artemia is one of the most important live foods in aquaculture. The aim of the current study was to investigate Microbiota of Artemia franciscana fed by bacterial probiotic Bacillus subtilis and yeast Saccharomyces cerevisiae under laboratory conditions. In this experimental research, 500 Artemia nauplius were transported to 1 liter Zug with salinity of 70ppt and fed daily by Dunaliella tertiolecta and wheat bran. The present study was carried out in 4 treatments, including control treatment (no additive probiotics), probiotic treatment of Saccharomyces cerevisiae, probiotic treatment of Bacillus subtilis, and equal combination of yeast and bacteria. Statistical tests including Duncan's new multiple range test and one-way analysis of variance were used. SPSS 21 and Excel 2013 software were also used. Findings: Bacterial probiotic treatment showed the highest colony count compared with other treatments (p<0.05). Treatment containing equal combination of yeast and bacteria had the highest colony after probiotic bacterial treatment (p<0.05). The highest number of Bacillus colonies in the body was obtained in probiotic bacterial treatment and combination of yeast and bacteria, respectively, which was significantly higher than control and yeast treatments (p<0.05). Based on the total number of Bacillus colonies, probiotic bacterial treatment showed a significant difference with other treatments and the lowest number of colony was related to probiotic yeast treatment (p<0.05). Compared with other treatments, the highest number of lactic acidic bacteria is in bacterial treatment. These probiotics can well place on the surface as well as inside the body of Artemia. Therefore, using Bacillus subtilis alone or with Saccharomyces cerevisiae can have a positive effect on the bacterial count of Artemia

The breeding of Huso huso is a relatively new industry in Iran. The aim of this study was to investigate the effect of different levels of choline on growth factors, carcass composition, and haematological-biochemical parameters in juvenile beluga (Huso huso). In this experimental study, 150 Huso huso in control, Cho2, Cho4, Cho6, and Cho8 treatments consisting of 0, 2, 4, 6, and 8g/kg-1 choline of food with 3 replicates per treatment were fed for 12 weeks to evaluate growth performance, carcass composition, and some haematological and serological parameters. The data were analysed by analysis of one way variance and Duncan test, using SPSS 24 software. Findings: The final weight, weight gain, specific growth rate index, protein efficiency ratio, obesity coefficient, and feed conversion ratio of fish fed with diet containing appropriate levels of choline (2-4g/kg-1) were significantly better than fish fed with other diets. The highest growth and food efficiency was observed in fish fed with Cho4. With increasing choline in fish diet, body fat and protein concentrations significantly increased, but carcass moisture decreased. Also, addition of 2-4g/kg-1 choline to diet caused a significant difference in the mean number of red and white cells, the activity of liver enzymes (alanine aminotransferase and aspartate aminotransferase), albumin, and total blood protein compared with control treatment. In order to achieve the best growth and optimal carcass composition of juvenile beluga, the most suitable amount of choline is 2-4g/kg-1 in the fish diet.

Heparin and EDTA salts are commonly used as anticoagulants for haematological studies in fish. This study aimed at investigating the effect of heparin and Ethylenediaminetetraacetic dihydrate (Na2EDTA) on some haematological parameters of Sterlet sturgeon (Acipenser ruthenus). In the current experimental study, the effect of heparin (10ml) and Na2EDTA (1mg/ml) was investigated on haematological parameters in Acipenser ruthenus. The blood samples were collected from 10 healthy fish with the average weight of 600.0±63.0g. The data were analyzed by SPSS 22 software, using one-way analysis of variance, independent t test, and Duncan's new multiple range test. Findings: The number of red blood cells in samples containing Na2EDTA (845000±123532cell/mm3) was significantly lower than those of heparinized ones (1205000±86270; p<0.05). Mean haematocrit value for Na2EDTA samples (27.05%±0.46) was significantly higher than bloods preserved in heparin (23.62%±0.89%; p<0.05). In sample containing Na2EDTA, mean corpuscular volume (MCV) and lymphocyte (149.11±30.00ft and 93.25±1.55%, respectively) was significantly higher than the heparin sample (108.59±18.41ft and 87.25±1.72%, respectively; p<0.05). In sample containing Na2EDTA, the increase in size and haemolysis of red blood cells were observed, but the changes in the sample containing heparin did not differ significantly from that of the control group. Na2EDTA has a negative effect on haematological parameters of Acipenser ruthenus, especially in morphological terms; so, it is not a suitable anticoagulant combination for blood analysis of this species. Heparin due to the smallest changes in shape and size of cell, as well as less effect on hematocrit, is an anticoagulant in sterilized fish haematological studies.

Considering the unsaturated nature of fatty acids, the use of technologies to control its oxidation rate is essential for use in the food industry. Thereafter, the aim of this study was to investigate the effects of biopolymer concentration and core material percentage on quality characteristics of fish oil nanocapsules containing clove essential oil prepared by complex coacervation technique. In the present experimental research, the effects of 3 independent variables including the total biopolymer percentage (gelatin-gum Arabic; 6, 8, and 10%), oil content (2 to 3%), and the concentration of clove essential oil (0, 2000, and 3000 ppm) on dependent variables such as size and zeta potential of particles, color, surface oil, encapsulation, and nanoencapsulation efficiency were evaluated. The present study was carried out as factorial experiment in a completely randomized design. One-way analysis of variance and Duncan test were used. The data were analyzed by SPSS 16 software. The increase in total biopolymer percentage was associated with increasing particle size as it was in the range between 259.19±55.83 and 814.35±253.05 nm, respectively. In terms of color parameters, the yellowness of produced powders was increased by increasing the concentration of fish oil and cloves essential oil, while lightness was decreased by increasing the concentration of the biopolymer. Also, the superficial oil was increased by increasing oil and clove essential oil concentrations in the nanocapsules, and microencapsulation efficiency in different treatments was recorded between 65.1±2.75 in treatment 15 (10% biopolymer and 3% oil) to 98.84±0.78 in treatment 4 (8% biopolymer and 2% oil). Using complex coacervation technique with gelatin-gum Arabic as a biopolymer can produce nano-sized particles.

In this study, the replacement effect of dietary fish meal with AquPro (Processed soybean meal) was assessed on growth performance, body composition and total protease activity of rainbow trout (Oncorhynchus mykiss) over a period of 6 weeks. In this experimental study, at the beginning of the trial, 5 experimental diets were formulated with fish meal as control (A) and diets with 25% (B), 50% (C), 75% (D) and 100% (E) AquPro, respectively. At the end of the feeding trial, growth performance, body composition and total protease activity from pyloric caeca and intestine were measured. The results indicated that the WG, SGR and ADG in experimental diet C were the highest and showed a significant difference with other treatments (p<0.05). However, the status index in experimental diet C was lower than other treatments, but did not show significant differences (p>0.05). The moisture content, fat, and body ash were respectively, significantly higher in experimental diets A, B and E than those of other treatments (p<0.05), But the highest amount of protein was observed in the experimental diet of C, which did not show any significant difference with other treatments (p>0.05). The highest total protease activity from pyloric caeca and the intestine was observed in the fish fed with diet C which showed a significant difference with other diets (p<0.05). Based on the results of growth performance, body composition, and total protease activity was revealed that the diet containing 50% AquPro could be appropriate for rainbow trout growth.

A wide range of chemical endocrine disrupters modifies DNA methylation. Like a weak class of estrogens, phytoestrogens can affect aquatic animal reproduction and disturb the structure of endocrine systems. In order to study the epigenetic effects of genistein and β-sitosterol, 49 female adults (for about 21 days) and fertilized eggs (until hatching time) of Kutum’s exposed to 3 different levels of genistein and β-sitosterol (10, 50, 500ng/l). At the end, the liver, the ovaries, and embryos were sampled and methylation-sensitive amplified polymorphism (MSAP) was used to evaluate the level of DNA methylation. According to result the fish exposed to high level of β-sitosterol shown hypo DNA methylation in the liver. Compared with control, both of these compounds could effect on the ovary and embryos DNA methylation pattern. The result showed, whole genome methylation had a different pattern in the liver, ovary, and embryos, which treated by 500ng/l of β-sitosterol. Methylation change pattern can be changed depends on the type of tissue and structure and level of the phytoestrogen compounds. According to this study, genistein and β-sitosterol could affect reproduction and embryo development by changing molecular indices. It seems that these compounds could affect the endocrine system of Kutum and reduce reproduction performance of Kutum in the long period.

Golden grey mullet (Liza aurata) and leaping mullet (Liza saliens) are two species from Mugilidae which inhabit the Caspian Sea. Despite the difference in the number of Pyloric caeca, lateral line scale, and gill rakers, diagnosis between two species regarding morphological plasticity is relatively difficult. In this experimental study, in addition to access previous morphological diagnostic characters, 31 morphometric and 10 meristic characters were surveyed. Also, COI gene sequence used to confirm accurate identification of these two commercial species in the Caspian Sea. In this way 25 samples were used for biometry. Samples were collected from Nur and Anzali cities beach sein fishing center in autumn and winter 2016. Among surveyed morphological characters, 3 meristic and 15 morphometric characters revealed a significant difference (p<0.05), respectively. Regarding the principal component analysis (PCA) results, Pre-pectoral fin length, Pelvic fin length, Anal fin base length, Caudal peduncle width, Anal fin height and Head width, within Morphometric characters and Second dorsal fin rays, lateral line scale number, number of Gill rackers and Pyloric caeca were among meristic characters which reveals highest load factor (>0.7) in discrimination of two species specimens. Regarding genetic distances, the between-group distance estimated 40bp (6.8%) or 0.078 K2P that well agreed with morphological identification. Results revealed the application of more morphological characters in the diagnosis of two Mullet species in the Caspian sea which could be useful in completing identification keys.

Iran has many potential and opportunities for the development of aquaculture with the goal of producing and diversifying food, improving food security, non-oil exports, foreign exchange, and most importantly, generating productive employment directly and indirectly. The aim of this study was to analyze the performance of the northern and southern provinces in the fisheries sector. Instruments and Methods: In this descriptive study, provinces including Bushehr, Khuzestan, Sistan and Baluchestan, Golestan, Guilan, Mazandaran, and Hormozgan were examined by Multi-Attribute Decision Making (MADM) and, in particular, the prioritization technique based on the technique for order of preference by similarity to ideal solution (TOPSIS). The data were collected, using the 2015 Statistical Yearbook of Fisheries Organization and the Statistical Yearbook of Iran. Multi-attribute decision making (MADM) was used to analyze the data. Findings: Based on the statistics used and the selected indices, Mazandaran had the best performance in the fisheries sector among the provinces. Guilan, Hormozgan, Khuzestan, Sistan and Baluchestan, Bushehr, and Golestan provinces were in the next ranks. In the fisheries sector, Mazandaran province has the best performance among the provinces of Guilan, Hormozgan, Khuzestan, Sistan and Baluchestan, Bushehr, and Golestan.