فصلنامه شیلات
سال هفتاد و سوم شماره 4 (زمستان 1399)

Sexual dimorphism is a phenomenon in some fish species and its understanding is crucial for their taxonomic studies, biology and evolution. Regarding differences in body coloration patterns between male and female of Caucasian dwarf goby, Knipowitschia caucasica, the question arises whether they are different in their body shape or not? Hence, this investigation was conducted to study the sexual dimorphism in body shape of Caucasian dwarf goby from the Gorgan Bay using landmark-based geometrics technique. For this purpose, a total of 120 specimens were collected from two populations i.e. the Gorgan Bay and Gomishan Wetland. Then, their left side were photographed and 21 defined landmark-points were digitized on the obtained 2D images. After GPA analysis, the data of both populations were analyzed separately using multivariate discriminant analysis and Hotelling T-test. The results showed a significant difference between the body shape of male and female in both studied populations that the distinction rate in the population of the Gomishan Wetland was higher. Based on the observed differences, the male has a deeper head, lower body depth at the level of the dorsal fins and, longer and low depth of the caudal peduncle. According to the results, it can be stated that sexual dimorphism in this species has been probably evolved due to the mechanism of sexual selection, which can be consider as functional advantages in reproductive processes and swimming performance in males. Hence, due to the sexual dimorphism in this species, in further morphological studies, two sexes should be examined separately.

Rosemary (Rosmarinus officinalis) has various biologically active metabolites with antioxidant, anti-inflammatory, anti-cancer and oxidative stress reduction properties.The current study was performed to examine the efficacy of dietary Rosmarinus officinalis commercial extract on some antioxidant and biochemical parameters in gold fish (Carassius auratus). Fish with mean weight 7.6 ± 0.5 g were divided into three groups and fed with 0 (as control group), 1 and 2 g kg - Rosmarinus officinalis extract for 40 days. Based on the results, lower lipid peroxidation product (MDA) was observed in the treatment groups (P<0.05). Meanwhile, activities of some antioxidant enzymes, including catalase, superoxide dismutase and glutathione peroxidase were higher in the treatment groups compared to the control group (P<0.05). Feeding with Rosmarinus officinalis extract also led to a significant decrease in aspartate aminotransferase (AST) (P<0.05), whereas no significant changes were noted in alkaline phosphatase (ALP) and glutathione S-transferase (GST) activities (P>0.05). Therefore, the results of this study show that the administration of 1 and 2 g kg - Rosmarinus officinalisextract had the potential to improve some antioxidant indices, as well as protecting the liver in gold fish and better results require more research.

This study examined the effects of different levels of dietary inclusion of Biotronic Top3 on growth, feeding and body biochemical composition of whiteleg shrimp, Litopenaeus vannamei reared at the Choebdeh Shrimp Culture Complex, Abadan for a period of 64 days. Shrimp with initial average weight of 4.28+0.05g were stocked randomly in fifteen 300l polyethelene tanks at a density of 25 shrimp/tanks. Triplicate groups of shrimp were hand fed to satiation four times a day using the experimental diet containing 0 (treatment 1, control), 0.5 (treatment 2), 1 (treatment 3) and 2 (treatment 4) grams per kilogram of Biotronic Top3. Biometry was done at the beginning and at the end of the experiment. After 64 days, shrimp receiving diets supplemented with Biotronic Top3 showed significantly better growth performance than those fed the control diet. The highest and the lowest weight gain, specific growth rate and survival rate were recorded in treatments 4 and 1, respectively. Feed conversion ratio, protein efficiency ratio and feed efficiency were significantly different between the treatments (p < 0.05). The highest FCR and the lowest PER were recorded in treatment 1 and the lowest FCR and the highest PER were recorded in treatment 4. Feed efficiency showed a trend similar to that of PER. Morphometric indices (total length, carapace length, orbit length), condition factor and body biochemical parameters were significantly different between the treatments (p < 0.05). The protein content was the highest in shrimp fed the diet containing Biotronic Top3. The highest and the lowest lipid contents were recorded in treatments 4 and 1, respectively. Based on our results and under the rearing conditions used in this study, inclusion of Biotronic Top3 at the rate of 2g/kg diet is recommended for feeding whiteleg shrimp, Litopenaeus vannamei.

The present study was conducted to investigate the effect of household income levels on shrimp purchasing behavior model in Tehran city. The statistical population of this study is the whole of Tehran city that from12 urban areas, 384 people (head of household) were randomly selected to complete the questionnaire (Information gathering tool). In order to investigate the effect of income levels on the model of household purchasing behavior, this statistical population was divided into two categories, namely households with incomes less than 5 million (A) and more than 5 million Tomans (B). Then hypotheses based on the behavior model were tested in both categories using the structural equation modeling (LISREL). The results showed that in category A households, subjective norm, behavior control element and as well as packaging, income, price, quality and type of supply and processing significantly affect the decision to purchase. But in category B households, unlike category A, price, income and behavior control element do not have a significant effect on the decision to purchase. In both groups of households, the access factor did not have a significant effect on the purchase decision. While the values of the effect coefficients showed that packaging and quality factors are the most important factors influencing the decision to purchase both categories.

Water’s oxidation-reduction potential (ORP) is one the of water’s physicochemical indexe that is affected by the combination of oxidizing and reducing agents. In addition to affecting many water quality parameters, this index alone reflects the general water quality conditions. The aim of this study was to investigate the effect of different levels of water oxidation-reduction potential (ORP) on some reproductive indices of the giant freshwater prawn female brood-stock. For this research, 4 treatments in triplicates with levels of 200-150 (control treatment), 250-200 (2nd treatment), 300-250 (3th treatment), 350-300 (4th treatment) mv were provided and checked and regulated by digital ORP meter daily. Reproductive indices including egg dry weight, fertilized egg percentage, egg hatching percentage, fertilizing rate, egg clutch somatic index (ESI), larval dry weight, larval stage index (LSI), and larval condition index (LCI) were evaluated. In each experimental unit with a volume of 80 liters, three female brood-stocks and one male were stocked for 8 weeks. Based on the results, the percentage of fertilization in the second treatment showed a significant increase (P <0.05) while the third and fourth treatments recorded a significant decrease (P <0.05). The LSI index of the second treatment significantly increased (P <0.05) with the first treatment (control), but the third treatment was not significantly different and the fourth treatment had a significant decrease (P <0.05). ESI, LCI and egg dry weight indices in the second treatment (200-250 mV) were not significantly different (P <0.05) but in the third and fourth treatments were significantly reduced (P <0.05). Egg dry weight in the third and fourth treatments had a significant decrease compared to the control treatment, but the second treatment did not record a significant difference. In general, according to the results of this study, keeping the levels of water,s ORP between 200-250 mv in the freshwater giant prawn -brood-stock tank provides the best reproductive performance.

In this study, non-market sizes of Ilisha fish, which are less welcomed by consumers, were used to produce surimi and the effect of Konjac gum on the physicochemical properties of the product produced from this type of fish was investigated. For this purpose, different amounts of Konjac gum in concentrations of 0.25, 0.50 and 0.75 % (w/w) were added to the surimi samples of Ilisha fish and compared with the control sample (without gum). Surimi and the produced gel were evaluated in terms of chemical composition, water holding capacity and color factors, and textural properties and sensory evaluation were performed on the produced gels. The results showed that by adding Konjac gum to surimi samples and surimi gels, the amount of lightness (L*) decreased compared to the control sample while the moisture and water holding capacity of the samples increased significantly (p<0.05). By increasing the concentration of Konjac in surimi gel, the parameters of texture (firmness, cohesiveness, adhesiveness, springiness, chewiness) increased significantly compared to the control sample. Sensory evaluations also showed that the panelists assigned the highest score to the 0.5 % Konjac treatment for surimi gel from the Ilisha. Based on the findings of the present study, it was found that Ilisha has the potential to produce surimi and by adding Konjac gum, its properties can be improved.

Due to exist of the different kinds of sea cucumbers and their biological activities, In this study, the antibacterial activities and the soap forming ability of powder, methanolic and saponins extracts of sea cucumber (Holothuria leucospilota). obtained from Lavan Island, were evaluated. Initially Sea cucumbers were dried and subsequently ground. Extraction was performed by methanol solvents to obtain total extract and 70% ethanol. The method of soaking was used in order to prepare the extract containing the ultimate amount of saponin compounds. With the aim of determine the quality of saponin, its index of foam forming ability was evaluated. The production of soap from marine cucumbers was carried out using the method of soaping fats and glycerin. Finally, sea cucumber soaps was produced using powder, methanolic and saponins extracts with ratios of 1, 5 and 10%. In order to fulfill of bacterial analysis, the effect of extracts and prepared soaps on Staphylococcus aureus was evaluated using tubular dilution method. The results of the experiment show that the minimum inhibitory concentration (MIC) of the methanolic extract and marine cucumber soap for Staphylococcus aureus is 10 and 5 mg / ml respectively. This index for saponin and its soap is 2 and 5 mg / ml. Regardless of the duration of the experiment, one-way analysis of variance test showed that there was a significant difference in the mean height between volumes of 10 ml and volumes of one, two, three, four and five ml (p <0.05). In other cases, no significant difference was observed in the mean floor height. The produced foam of the sea cucumber saponin remained for more than 12 hours, indicating a very high foam formin ability. In this project, the antibacterial and consequently anti- pimple of extracts and soaps produced from the Holothuria leucospilotaobtained from Lavan Island were studied and confirmed. Therefore, this compounds can be used as an appropriate choice for the production of anti-pimple soaps.

The prediction of the habitat suitability of freshwater shrimp (Macrobrachium nipponense) is an important issue for managing the aquatic ecosystems. Six sampling sites were selected from different parts of the catchment area of ​​Anzali wetland to predict the habitat conditions of freshwater shrimp in which the species was present in three sampling sites (36 instances) and it was absent in the remaining of the sampling sites (36 instances). In total, fifteen environmental factors consisting of water quality, dynamic and structural variables were monthly sampled based on the biological variable (the presence/absence of shrimp) over one-year sampling period (1397-1398). The prediction of SVM was reliable based on the two predictive performances (CCI% and Cohen kappa) since both predictive performances exceeded the threshold values (CCI%> 70% and Cohen kappa>0.70). The results of the support vector machine model showed that the population decline or even the absence of shrimp might have a very close relation with increasing water flow velocity, water depth, salinity, electric conductivity, sodium and chloride concentrations. Based on the model outcomes, increasing the concentration of other water quality variables including potassium, sulfate and total hardness might have an intermediate impact and increasing the concentration of orthophosphate, nitrate and biological oxygen demand might have less impact on the prediction of the shrimp habitat. Contrary to the above-mentioned variables, the results of the applied model showed that increasing the concentration of some variables such as dissolved oxygen, acidity and water turbidity might increase the probability of the shrimp presence in the sampling locations. Based on the factors predicted by the model, the importance of these factors should be considered for freshwater shrimp in future monitoring.

Lipid-containing Food and specially seafood products are vulnerable to oxidative deterioration, so it is vital to maintain its quality with different ways that are cost-effective. The aim of this study was to produce an antioxidant compound from fish by-product, in order to prevent the disposal of this by-product in the environment and to provide a product that can be used in the food industry. For this purpose, the viscera of common carp (Cyprinus carpio) was hydrolyzed with alcalase enzyme (concentration 1%, temperature 55 ° C and pH 8) at different times including 30, 60, 120 and 180 minutes and their antioxidant activity were compared. The results showed that the protein hydrolysate obtained after 180 minutes of hydrolysis, had significantly higher degree of hydrolysis and better antioxidant performance than 30, 60 and 120 minutes (P <0.05) The highest degree of hydrolysis was 56.66± 0.18%. According to the results of antioxidant activity, IC50 values ​​of DPPH and ABTS radical scavenging power at 180 minutes were 1.34±0.01 and 1.92±0.026 (mg/ml), respectively, and iron reducing power was 0.261±0.01 (OD at 700 nm). Overally, the results showed the protein hydrolysate derived from common carp viscera had antioxidant properties and the hydrolysis time (up to 180 min) affected on degree of hydrolysis and antioxidant properties.

In a nutritional experiment, Bacillus subtilis, Bacillus lichenifirmis and yeast of Saccharomyces cerevisiae isolated from the intestine of Beluga (Huso huso) in suspended blend at three different concentrations (1.5×106, 3×106 and 4.5×106 CFU/g) and added to basal diet and considered as experimental treatments. The common carp (Cyprinus carpio) larvae were fed the experimental diet for a period of 45 days. At the end of the feeding period, larvae were exposed to various environmental stresses challenges containing: high level of ammonia (5 mg/L), high thermal pressure (40Cᵒ), low Acid (pH=2) and high Alkaline (pH=12) conditions. Furthermore, Biochemical parameters were measured after preparing the larval body extract through the routine method. The results showed that growth indices increased significantly in experimental treatments compared to control group (p <0.05). The highest survival rate of larvae was recorded in T3 treatment against environmental stresses (p < 0.05). The highest Na+ and K+ ions in larval body extract was measured in T3 treatment (p <0.05). The highest glucose level was measured in T2 treatment (p <0.05). Cortisol level in T3 treatment was significantly lower than other experimental treatments (p <0.05). The results of this study indicated that the simultaneous use of Bacillus and yeast probiotics in diet of common carp larvae, isolated from the gastrointestinal tract of Beluga, had positive and significant effects on improving the growth parameters, biochemical compounds of body extract, survival rate and resistance against environmental stresses, especially, at the level of 4.5 10 106 CFU/g.

MicroRNAs are short noncoding RNAs that control gene expression in post-transcriptionally manner, estimated about 60% of all genes controlled by these RNAs. Among vertebrates in Salmonids this type of RNA poorly investigated. In this study for profiling isoforms of Let-7 MicroRNA of Salmonids, the data from NCBI database was extracted and analyzed. About 43 million reads with 22 nucleotides span were analyzed. Among them, 17.8 million reads were matched to to Let-7a isomer of this MicroRNA family. 9 Isoforms of this family detected in which 8 of them were detected before in other animals. One of detected isoforms was novel and not reported in other species. The novel isolated isoform in this study contains one nucleotide difference with Let-7f in Atlantic salmon (salmo salar). let-7a isomer abundantly expressed comparing with others. 20 loci for all isomers were on reference genome (Otsh.V1) in NCBI, and 7 of these loci organized as MicroRNA gene clusters in genome. The other 2 loci for Let-7c were detected on unplaced fragments of reference genome as well.