نشریه علوم و فنون شیلات
سال دوازدهم شماره 2 (پیاپی 42، بهار 1402)

Annually, millions of rainbow trout frys are produced in Iranian hatcheries, however, millions of selected stocks of rainbow trout eyed eggs are also imported for breeding in farms. Despite the interest of many rainbow trout farmers to use imported fish for breeding, there is no clear information about the superiority of growth and survival of these imported strains over the rainbow trout that are produced in Iranian hatcheries. For this purpose, in the present study, the growth parameters of 432 individuals of either imported Spanish and Iranian strains of rainbow trout reared in 12 ponds using both river and spring water sources (four treatments and three replicates) were investigated and compared for 90 days. At the end of the experiment, a significantly higher weight and length gain, and specific growth rate was observed in Spanish rainbow trout compared to Iranian strain in both water sources (river and spring) (p < 0.05). Moreover, the food conversion factor was significantly lower in Spanish strain than Iranian rainbow trout) (p < 0.05). These results showed that the selection breeding could remarkably enhance growth performance and consequently cause more production and profit for rainbow trout farmers.

AbstractIn the present study, The effect of phthalate ester toxicity (0.1 and 1 mg/L) was investigated on some non-specific mucus parameters of common carp (Cyprinus carpio). 180 common carp (17.60±2.22gr) is gathered from warm water fish center and they were allocated into 9 tanks (20 Fish per tank). Fish adapted to new condition for a week. During this time; they were feed twice a day with same diets. Fishes were exposed at 3 concentration treatments containing 0; 0.1 and 1 mg/L DEHP under laboratory condition (25±0.5°C; pH: 7.4-8) for a period of 96 hours. Alkaline phosphatase, lysozyme, soluble protein, and immunoglobulin of mucus was measured and evaluated. The results showed that the levels of lysozyme, alkaline phosphatase and immunoglobulin in common carp skin mucus decreased when exposed to DEHP (with increasing concentration and exposure duration) And the level of soluble protein of common carp skin mucus increased when exposed to DEHP (with increasing concentration and exposure duration). These results indicated that concentrations of DEHP beneficially affects Amino Acid profiles of skin mucus in carp and they were categorized in 4 branches. There were Significant differences between exposed and control groups. Therefore; fish skin mucus can be a biomarker for showing contaminants and toxins. And the high consumption of plastic materials can be a warning to the health of aquatic animals and humans.

Zebrafish is considered as a useful laboratory model due to its diverse characteristics, including self-renewal. The embryo of this fish has unique characteristics in the early stages of development, and its effects were observed in various studies. The differentiating factors present in stem cells isolated from zebrafish embryos are effective in improving the functional status of patients, and exposure to zebrafish embryo extracts in the early stages of development may increase the expression of multipotent stem cells and exert positive effects.  In this study, we investigated the antioxidant properties of the zebrafish embryo extract in different embryonic stages of development.The Zebrafish egg extract was prepared in different embryonic stages. Its effect in concentrations of 0.5, 1, 1.5 and 2 mg/ml on DPPH free radical scavenging activity, ABTS radical inhibitory activity and iron reducing power (FRAP) were investigated. The studied groups included protein extracts in morula, blastula and gastrula stages. According to the obtained results, the amount of protein varied in different embryonic stages and the amount of protein increased with the progress of fetal growth and the amount of fat decreased.The protein extract in the gastrula stage showed the highest level of DPPH inhibition and iron ion reduction at a concentration of 2 mg/ml compared to the morula and blastula groups (P<0.05). Also, the protein extract in the embryonic stage of blastula had the highest inhibition of ABTS at a concentration of 2 mg/ml compared to other groups (P<0.05).

In this study, the effect of different hydrolysis times (45, 90, 135, 180, and 225 minutes) by alcalase enzyme on the yield and quality of oil extracted from common kilka fish (Clupeonella cultriventris caspia) was investigated. The results showed that the highest extraction yield (40.41%) was in the hydrolyzed treatment for 135 minutes, which was not significantly different from other treatments. The qualitative indices of TBA, FFA, and CD of the extracted oils increased by increasing hydrolysis time, so the highest value of the mentioned indices was at 225 minutes, while the highest value of the PV index was at 180 minutes. Because the treatment of oil extracted in 45 minutes had lower values in the investigated oxidative spoilage indicators, it was selected as the treatment. The composition of its fatty acids was investigated, and it was found that monounsaturated fatty acids were the predominant fatty acids. Also, the amounts of saturated and polyunsaturated fatty acids did not show significant differences (p < 0.05). According to the obtained results, it was found that different hydrolysis times have different effects on the yield and quality of the obtained oil. Therefore, more research and studies are needed to fully investigate the effect of hydrolysis time on the quality characteristics of the oil extracted from Kilka fish.

Chitosan (Cs) was extracted from shrimp shell and its derivative forms including N-alkyl (AlkCs) and nanoparticles (CsNPs) were prepared. First, the properties of nanoparticles were determined by dynamic light scattering (DLS) and the morphology of nanoparticles and N-alkylated by scanning electron microscopy (SEM). Then their antibacterial activity was evaluated by the test of minimum inhibitory (MIC) and lethal (MBC) concentration, diffusion on agar by disk, permeability of cell membrane by measurement of cytoplasmic beta-galactosidase release (ONPG). The type of apoptosis cell death was also examined by DAPI staining and changes in cell surface integrity by atomic force microscopy (AFM). The results showed that the nanoparticles are spherical with an average hydrodynamic diameter of 240 nm. N-alkyl had a rough surface structure compared to native chitosan. At the least of MIC (78 μg/ml) and MBC (100 μg/ml) points were observed for CsNPs (P < 0.05). Nanoparticles and N-alkyl of chitosan showed the highest diameter of growth inhibition zone at 1250 concentration compared to other disks (p <0.05). Outer membrane permeability of derivative forms of chitosan showed significant differences with native chitosan and cells of control. DAPI staining test showed higher cell death of chitosan-derived forms. DAPI staining test showed higher cell death of derivative of chitosan. The images obtained from AFM showed a change in the membrane integrity of the treated cells compared to spherical and clustered of control cells. Thus, the antibacterial properties of native chitosan improved by physical and chemical modification.

This study was conducted to compare the morphological characteristics of wild and farmed common carp. In total 70 samples of common carp, including 25 samples of wild from Torkaman port and 45 samples of farmed common carp from Silver carp center in Gilan province were collected. Morphometric results were standardized using Elliott formula, and then principal component analysis (PCA) and discriminant function analysis (DFA) were used. Independent t-test was used to evaluate the significance of traits between these two populations. The results of this study revealed that the two populations of wild and farmed common craps were completely separated from each other, using PCA and individuals were assigned to their true population with high accuracy (98%) based on DFA. Among the 33 truss distances that were analyzed, 16 distances showed a significant difference between two populations (p<0.05). The results showed that the studied populations can be distinguished by many morphological differences, especially by dorsal fin length, pectoral fin length, pelvic fin length, anal fin length, dorsal fin width, body width, tail stem width, distance between pectoral and pelvic fin, distance from mouth to dorsal fin and the distance from the mouth to the anal fin. Overall, the results showed that the population of wild carp was significantly different from the population of farmed common carp from the morphological point of view.

The purpose of this research is to investigate the relative importance of Avicennia marina organic matter in the feeding of Ilisha melastoma fish in the Mangrove Biosphere Reserve; It was stable isotope approach. Three primary food sources including mangrove tree leaves, microphytobenthos and suspended organic particles were analyzed isotopically. The samples of primary food sources and fish are converted into pure and simple gases such as CO, CO2 and N2 after minimizing the size and turning into powder. Then the identified isotope ratios are compared with a measured standard and the exact amount of isotope formed in the sample is obtained. In this research, sampling was done seasonally in August in the summer season and February in the winter season of 2019 in the mangrove ecosystems of Bandar Khmer, Hormozgan province.In the summer season, the average stable carbon isotope of primary food sources fluctuated from -28.07 units per thousand for mangrove leaves to -13.58 units per thousand for microphytobenthos.This average in the winter season was obtained from -28.05 units per thousand for mangrove leaves to -13.54 units per thousand for microphytobenthos.The average stable nitrogen isotope of primary food sources in the summer season fluctuated from 1.44 units per thousand for microphytobenthos to 10.72 units per thousand for suspended organic particles.The results of this research showed that in the summer season, suspended organic particles with 63% and in the winter season, microphytobenthos with 45% play the most important role in providing the food needed by the small shemsk fish.