نشریه علوم و فنون شیلات
سال دوازدهم شماره 3 (پیاپی 43، تابستان 1402)

The present study was conducted in order to obtain the necessary information on the diversity, abundance and distribution of macroinvertebrates, as well as to investigate the grazing status of batoid fishes (stingrays) from benthic macroinvertebrtes in coastal waters of Hormozgan province. For this purpose, sampling was done in the years 2017 and 2018 and once every year in the autumn season. At the end of the identification process, a number of 125 genus and 104 species belonging to 85 families, 31 classes, 9 orders, and 7 phyla were successfully identified. Results revealed that Malacostraca was the frequent order in the studied area. In order to investigate the possible relationship between composition and abundance of benthic macroinvertebrte and stingrays, CCA analysis was employed. Results of stomach content of stingrays revealed that in the diet of M. randall, crustacean (93.25 %IRI) has the highest amount. This pattern was the same for M. gerrardi and H. walga. However, in M. gerrardi, bivalvia were in the first place of importance (31.33 %IRI). Also, trophic level analysis was done for three species which shows all species are Mesopredators that place in the same level of food web. According to the mentioned cases, some benthic macroinvertebrates identified in this research have a significant  relationship with the benthic fishes, which requires more studies to investigate their relationship.

In this experiment fish meal was replaced with RPC by levels of 0, 25, 50, 75, and 100%. Diets fed to kutum (initial weight of 340±20 mg) three times daily for 60 days. The highest final weight (1020 mg) and weight gain (670 mg) and the lowest FCR (1.5) were observed in the 50% substitution treatment, which was significantly different from the other treatments (P < 0.05). The survival rate was 100% and the same for all diets. No significant difference was observed in carcass composition (moisture, protein, lipid and ash) between different treatments (P > 0.05). By increasing the amount of rice protein concentrate, the amount of n-3 decreased and the amount of n-6 increased (P<0.05). The ratio of n-3 to n-6 did not change significantly up to the level of 25%, but it showed a significant decrease with the increase of the substitution level. The amount of total amino acid did not change significantly among the treatments with the increase in the concentration level. The highest amount of essential amino acids was related to the 25% treatment, which was significantly different from the control, 50, 75 and 100% replacement treatments. In general, the results of this study showed that rice protein concentrate can be used as a substitute for fish meal up to 50% in the diet without significant change in the growth of Kutum fry. Of course, the quality of carcass fatty acids was not maintained at this level, and the 25% level was more suitable.

This study was conducted to investigate the effect of adding Bacillus subtilis (IS02) to the diet on survival, biochemical indices, and histological alternations of juvenile wild common carp, Cyprinus carpio, exposed to salinity stress. Juvenile common carp (about 1.1 g) were fed diets containing 0 (control), 2.5 × 108 (pro-8), and 2.5 × 109 (pro-9) cfu/g probiotic for 15 days and then transferred directly to brackish water (13 g/L) and sampled after 3 and 10 days. Diet and sampling time had no significant effect on fish survival, which was above 96% in all treatments. Body moisture and potassium were only affected by sampling time, with moisture decreasing significantly after salinity stress while potassium increased significantly. Whole body sodium in pro-8 treatment did not change significantly during salinity stress, and probiotic treatments had lower chloride levels than the control before and after salinity stress. Adding probiotic to the diet increased glutathione reductase, glutathione peroxidase activity, and reduced glutathione concentration, while decreasing malondialdehyde concentration. Probiotics caused white blood cells infiltration in the kidney tissue. No significant tissue damage was observed in the gill and kidney, compared to the control after salinity stress. This study shows that juvenile wild common carp can tolerate direct transfer to the Caspian Sea without dietary probiotic supplementation. However, probiotic stimulates the kidney immunity, enhances ionoregulation, and increase antioxidant capacity in fish, which can have beneficial effects under field conditions.

The aim of this study was to produce protein isolates from the head of the Siberian sturgeon (Acipenser baerii) and study its functional and structural properties. Fish protein isolates were prepared by the pH shift method using alkaline pHs 10.5, 11, 11.5, 12, and 12.5. The results showed that the efficiency of protein extraction and its amount of essential amino acids at pH 11.5 were higher than other treatments. Furthermore, the results of determination of functional properties such as Water Holding Capacity, Oil Holding Capacity, emulsifying properties, foaming and solubility of the isolated proteins showed that as the pH increased, the functional properties improved and the protein isolates at pH 11.5 compared with other treatments was significantly higher. (p < 0.05). Comparison of the color characteristics (L, a and b) of the isolated proteins showed at pH 12 were more bright (higher L parameter) than those isolated in other treatments tested. In addition, the amount of red (parameter a) and yellowness (parameter b) of the isolated proteins decreased with increasing pH. The results of the organoleptic examination of the smell and taste of protein isolates at pH 11.5 are the most common among other treatments. According to the observed cases, the results show that the resulting Siberian sturgeon isolate protein has favorable functional properties and that the use of alkaline pH changes can lead to improved functional properties and parameters of color protein isolates.

The extrusion process is widely used in making aquatic feeds. The aim of this study was to investigate the effects of extrusion on biochemical analysis, removal of phenolic compounds and protein and carbohydrate digestibility of wheat flour in common carp. In treatments 1, 2 and 3 wheat flour was mixed with tap water at the rate of 250, 100 and 200 ml per kg of flour and then extruded by a single-axis extruder under the temperature of 120, 135 and 120 °C, respectively. Treatment 4 (control) was not subjected to the conditions of dough preparation and then extrusion. Extruding had no significant effect on the amount of crude protein and ash of wheat flour (p>0.05) but it significantly decreased the content of crude lipid, total phenolic compounds and non-tannin phenolic compounds and increased the digestibility of carbohydrate and protein (p<0.05). There were no significant differences in the amount of crude protein, crude lipid, ash and non-tannin phenolic compounds in the extruded treatments, but significantly the lowest amount of total phenolic compounds was recorded in treatments 1 and 2. Significantly, the highest carbohydrate digestibility was obtained in treatments 1 and 2, and the highest protein digestibility was observed in treatment 2. In total, treatment 2 (135 °C and 100 ml tap water per kg flour) was recognized as the best extruded wheat flour for common carp.

The present study aimed to isolate the steroids and fatty acids from the liver of the Persian Gulf spot tail shark Carcharhinus sorrah and to assess their antifungal activity. Extraction was done by methanol 70% and then, the lipids were separated through column chromatography with silica gel. Identification of the extracted lipids was done by thin layer chromatography and gas chromatography coupled with mass spectrometry. Then, antifungal activity of the steroids was investigated through determining the minimum inhibition concentration and minimum fungicidal concentration by tubular dilution method against Aspergillus fumigatus and Candida albicans. Identification of the extracted compounds by GC-MS confirmed the presence of these steroids in the shark liver. The identified steroids included compounds of Y-Sitosterol, Desmosterol and Squalene, which showed different results regarding the growth inhibition and fungicidal effects against the microorganisms at different experimental doses. Desmosterol and Squalene at minimum concentration induced the highest inhibitory effect on the fungus but Y-Sitosterol induced the highest inhibitory effect on the yeast. Squalene showed fungicidal effect only on the fungus and totally, A. fumigatus was more sensitive to the antimicrobial activity of the liver compounds than C.  albicans. In conclusion, promising results were found regarding the antimicrobial activity of the lipid compounds derived from Persian Gulf shark liver, revealing the importance of more comprehensive investigations of these natural compounds for the synthesis of biomedicines from the marine organisms.

This study was performed to determine the identification (barcoding) using cytochrome oxidase gene of common carp, between three provinces of Golestan, Mazandaran and Gilan (respectively in Gomishan, Tajan and Kiashahr) in 2011. The results of sequencing showed that all samples from the three regions had a genetic distance less than 2%, so all samples were from the same species. The results of sequencing 30 tail samples of carp species on the southern shores of the Caspian Sea showed that all samples are of the same species and their genetic distance does not reach at least 2%. Therefore, all carp samples of the three provinces are of the same species and have the same type of barcode. In the study of nucleotide and haplotypic distance, Gomishan region was 10.75000, 1 and Kiashahr region were 3.200 and 0.9333, respectively. In the study of nucleotide diversity between the two regions, 0.01978 and the average nucleotide difference was 12.187. Haplotypic diversity in Gomishan region was 38.095 and in Kiashahr region was 23.809%. Out of 13 haplotypes, Gomishan region with 8 haplotypes (61.53%) and Kiashahr region with 5 haplotypes (38.46%) had the lowest haplotypes.The results of this study show that there is a significant difference between carp samples in Gomishan and Kiashahr regions in terms of nucleotide and haplotypic diversity (P <0.05).