مجله علمی شیلات ایران
سال سی‌ام شماره 5 (پیاپی 127، آذر و دی 1400)

In current study, the effect of different times of molasses addition on water quality and immune performance of Nile tilapia (Oreochromis niloticus( mucus in biofloc system with limited water exchange was investigated. Nile tilapia with an average weight of 1.53 g was cultured in fiberglass tanks (circular cross section) with a volume of 130 liters of water at a density of one fish per liter for 37 days. Five experimental groups were considered including a control (without biofloc) group without carbonaceous substance addition and four biofloc treatments with molasses added daily (biofloc 1), once every two days (biofloc 2), once every three days (biofloc 3) and once every four days (biofloc 4). 2.5 ml/l microbial mass was added as a starter to biofloc treatments. Also, molasses carbonaceous material (65% of the input feed) was used to adjust the carbon to nitrogen ratio. According to the results, water quality in biofloc treatments showed that the lowest amount of total ammonia nitrogen (0.23 mg/l) and the highest amount of nitrate (25.5 mg/l) were obtained in biofloc 1 treatment (daily molasses addition), that showed a significant difference with other treatments (p<0.05). Based on the results of immune function of tilapia mucus, the lowest amount of total immunoglobulin (43.66 mg/100 ml) and lysozyme activity (17.33 ml/min) were observed in the control (without biofloc) group (p<0.05). Generally, the current research showed that the water quality in the biofloc system is improved with the addition of molasses on a daily basis and also the immune function of Nile tilapia mucus in biofloc system is more active than the normal system without microbial floc.

The present study was conducted to evaluate the effect of enriched Artemia urmiana with Chaetoceros sp. microalgae on fatty acid composition and antioxidant status of Litopenaeus vannamei for two months. This study was conducted in a completely randomized design with 3000 post- larvae of shrimp (with an average weight of 0.36±0.03 g) in four treatments and three replicates (n=250 in each replicate), including a control group fed with un-enriched Artemia nauplius, other groups (treatment 2, 3, and 4) fed with Artemia nauplius enriched with Chaetoceros sp. microalgae with 442×104, 348×104 and 120×104 cell/mL densities respectively. The results showed that at the end of the experiment, the highest EPA (6.95± 0.35%) and DHA (7.91±1.07 %), arachidonic acid (AA; 6.28± 1.02%), gamma-Linolenic acid (0.87±0.12 %) and stearic acid (9.75±0.15 %) was showed in treatment 4. Also, the highest, superoxide dismutase (SOD, 26.12±2.18 Unit/mL), glutathione Peroxidase (GPx, 83.10±4.80 Unit/ mL), and catalase (CAT, 5.38±0.12 Unit/mL) shown in treatment 4 which showed significant difference compared to other treatments (P<0.05). Overall, the results of this study showed that treatments fed with enriched Artemia nauplius with different densities of Chaetoceros sp. microalgae showed better fatty acid composition and antioxidant status compared to those of the control. And the use of enriched Artemia nauplius with a density 120× 104 cell/mL of Chaetoceros sp. microalgae are recommended in Litopenaeus vanname post larvae.

This study uses data of 5 Iranian industrial purse seiners that fish on free school tuna species in the Oman Sea. The catch data from 2015 to 2019 in the Oman Sea waters were used. The essential fish habitat of Thunnus tonggol was modeled using Satellite remote sensing (HYCOM. and MODIS). Redundancy analysis (RDA) was applied to provide a preliminary view of relationships between fish presence/absence and environmental variables, followed by the application of the Generalized Additive Model (GAM). According to GAM the presence/absence of T. tonggol is related to Latitude, Sea Surface Temperature (SST), Sea surface current velocity, and sea surface salinity (SSS). EFH maps were generated using GAM model based on the probability of the presence of T. tonggol. Latitude 23N to 25N degrees and longitude 57E to 60 E degrees are the preferred habitats of T. tonggol that are distributed in high density in these areas and indicate the habitat of this species in the continental shelf and coastal waters. Based on the analysis the distribution and density of T. tonggol on the east side of the Oman Sea Iranian waters, from Beris to Gwatar Bay, could be neglectable. Based on the results of the present study, it seems that, although, the relationship between chlorophyll-a concentration, sea surface height (SSH) and distribution, of T. tonggol is statistically significant, still the Latitude, Sea Surface Temperature (SST), Sea surface current velocity, and Sea surface salinity (SSS are the most important factors affecting the abundance of this species in the region.

Mercury causes oxidative stress in the body by producing oxygen free radicals and destroying antioxidant sources. The most important application of selenium is its role in the construction of antioxidant enzymes such as glutathione peroxidase, the function of which is to eliminate free radicals and reactive oxygen species. The aim of this study was to investigate the antioxidant effect of selenium nanoparticles and sodium selenite on biochemical parameters and antioxidant defense in Acanthopagrus latus in the presence of mercury chloride. A total number of 300 fish (25±3 g) were randomly distributed in five groups according to diet: control, nanoSe and sodium selenite (1 and 1.5 mg/kg). Fish were fed with experimental diets for six weeks. They were then exposed to a sublethal dose of HgCl2 for two weeks. At the end of the feeding period and after exposure, blood and liver samples were taken from all treatments and the activity of liver enzymes and antioxidants were measured. After six weeks of feeding the results showed that the form of selenium nanoparticles improved growth performance, increased the activity of antioxidant enzymes GPX and CAT and reduced the content of MDA, AST and ALT (p<0.05). The results showed that the form of selenium nanoparticles was more effective than the inorganic form of selenium during the period of exposure in increasing the activity of the antioxidant enzymes GPX and CAT. Decreased MDA content in the liver of fish fed selenium nanoparticles indicated a reduction in lipid peroxidation and a reduction in oxidative stress. The activity of ALT, AST and ALP enzymes increased more in the groups fed with selenium sodium than in the groups fed with nanoparticles (p<0.05). This study showed that the addition of selenium nanoparticles to the basic diet was more effective in terms of growth and antioxidant indices in yellowfin porgy (A. latus) after exposure to mercury chloride.

This study was carried out to compare the effect of different culture systems on the growth performance and body composition of common carp (Cyprinus carpio). Fish juvenile was selected by initial average weight of 21.5 ±0. 3 after designs the systems and adaptation period were randomly distributed in fiberglass tanks (with 100 liters capacity). The experiment lasted for 2 months.  At the end of experiment, growth parameters including final weight, weight gain percentage, specific growth rate, survival; and whole body proximate analyses including protein, fat and ash levels were examined. Finally, there were significant differences in final weight, specific growth rate, and feed conversion ratio and survival rate between experimental treatments (p<0.05). There was no significant difference between treatments (biofloc, recirculating aquaculture system) for whole body’s moisture, fat and protein (p>0.05). But there was a significant difference among body protein, ash and fat among control 2 treatment and other treatments (p<0.05). Also there was no significant difference between biofloc and recirculating aquaculture system for lysozyme and complement activity in treatments whereas the fish in biofloc showed a significant higher superoxide dismutase than the others (p<0.05). The results obtained in this experiment, suggest that biofloc improves growth parameters, immune response even with decreasing percentage of daily feeding in common carp.

The aim of the present study was to evaluate the feasibility of using biosilage produced from chicken waste and to replace this product in the diet of rainbow trout instead of fish meal. Because biosilage has higher properties and lower prices than fish meal. For this purpose, after producing biosilage based on fermentation of autogenous bacteria, is added to the diet formulation in the form of two treatments of 50% biosilage -50% fish meal and 100% biosilage and the growth performances and feed efficiency (WG, CF, SGR, FCR, PER) indices of these two treatments along with the control treatment (100% fish meal) on days 30 and 50 were evaluated and compared. The results showed that the indicators of WG, CF and SGR, in the treatment with 50% biosilage -50% fish meal are significantly higher than the other two treatments. It was also found that this treatment is more favorable than the other two treatments in terms of FCR and PER. According to the results, biosilage produced from chicken waste is a good alternative to fish meal. In addition, 50% biosilage-50 fish meal treatment is more desirable in terms of growth and feed index than 100% fish meal and 100% biosilage treatment.

The aim of this study was to investigate the functional properties of bioactive peptides produced from shrimp wastes in processing centers in three degrees of hydrolysis. For this purpose, the wastes of shrimp processing centers were hydrolyzed in three times of one, two and three hours using protamex enzyme and the functional properties of the resulting peptides (SPH1, SPH2 and SPH3) were evaluated. The results showed that with increasing the hydrolysis time from one to two and three hours, the degree of hydrolysis and nitrogen recovery of the process increased significantly (p<0.05). According to the findings, the solubility of SPH3 was significantly higher than SPH1 and SPH2 and its maximum was reported at pH=10, equal to 97.82±1.54% (p<0.05). SPH1 had higher emulsifying activity and emulsion stability index than SPH2 and SPH3. In this peptide, the highest value of emulsifying activity index was reported 68.15±2.84 m2/g, which was related to pH=10. But the maximum emulsion stability index was reported at pH=6 (166.84±5.08 minute). The highest measured foaming activity was 165.52±5.91% which was recorded at SPH1 and pH=10. Also, the maximum foam stability among the peptides was measured 118.32±3.23%, which was related to SPH1 at pH=6. SPH1 had a higher oil absorption capacity (5.92±0.33 ml/g) than SPH2 and SPH3 (p<0.05). The highest water holding capacity (5.18±0.71 ml/g) was related to SPH3 (p<0.05). According to the findings, the functional properties of peptides produced from wastes of shrimp processing centers using protamax enzyme are at an acceptable level for use in various foods.

In the present study, the effect of seasonal variability was investigated on the antioxidant content of brown algae Nizamuddinia zanardinii in the pre (April to June 2019) and post (October to December 2019) monsoon periods. Sampling was performed from Tang Bay, Chabahar Port and Goater Bay. T-test results indicated that all indices except IC50 were significantly higher in post monsoone condition compared pre monsoon (p<0.05). While, IC50 significantly higher in pre monsoon (p<0.05).  Comparison of results between stations indicated the levels of anthocyanin (4.13±0.97 DW/mg) and FRAB (0.56±0.02%) at Goater bay in pre monsoon were significantly lower than compared other stations (p<0.05); While, there was no significant difference between stations in post monsoon (p>0.05). The level of flavonoids showed a significant difference between all three stations in post monsoon (p<0.05); whereas no significant difference was observed between stations in pre monsoon (p>0.05). The highest amount of flavonoids in post monsoon were measured at Chabahar Bay Station (5.41±1.51 mg QE/100g DW). The highest level of IC50 was measured in both pre and post monsoon at Goater Bay (respectively 69.68±2 2.20 and 126.08±13.09 μg/ml), which was significantly higher than compared to other stations (p<0.05); But there was no significant difference between other stations in pre and post Monsoon (p>0.05).In conclusion, the results of this study showed that the level of antioxidant activity of N. zanardinii algae except IC50 after monsoon is significantly higher than pre- monsoon conditions. These results can be considered in the study of antioxidant potential of this species for commercial activities.

This study was conducted in 2017 by sampling from 7 stations in the headwaters of the Taleghan River to study the habitat suitability of Brown trout, Salmo trutta. Sampling was carried out using an electrofishing device with three replications in each station. Eight environmental factors, including water temperature (°C), water depth (cm), river width (m), slope (degree), water velocity (m/s), average diameter of the dominant bedrock (cm), potamal width and elevations were measured. The values of suitability index of the studied factors in each station were determined and the arithmetic mean of the indices in all sampling stations was considered as the suitability index of that factor. The results showed that the most preferred temperature is in the range of 10-5-12°C, depth in 20-30cm, river width in of 2.5-3m, slope in 1.6-1.9, water velocity in 0.41-0.62m/s, elevation in 2250-300 m and average diameter of the dominant bedrock in 11-20cm, and the potamal width 1.8-3.6m were calculated. As a general conclusion, the Taleghan River had a moderate suitability for S. trutta.

One of the main prerequisites for success in the microalgae production industry and the extraction of natural pigments from them is the selection of a suitable microalgae strain for culture. In this study, for the first time, isolation, purification and identification of native strain of Cyanothece sp. Chabahar was taken from Lipar back barrier (salinity up to 400 part per thousand, ppt). In the next step, to find suitable conditions for growing, this microalga was cultured in five different salinity levels (37, 60, 90, 120, 180 ppt) and growth rate, biomass production, chlorophyll a and b pigment content, total carotenoids and phycocyanin were assayed. The growth performance was performed by cell counting and measuring pigments using a spectrophotometer method. The analysis of data showed that increasing salinity from 37 to 90 ppt increased the number of microalgae cells and biomass and the maximum number of cells was 5×106 cells per ml and biomass 1.4 g/L was obtained at a salinity of 90 ppt. The maximum contents of chlorophyll a, chlorophyll b and phycocyanin were obtained (32μg/ml), (17μg/ml) and (2.47 μg/ml) at 90 ppt salinity, respectively. By increasing the salinity from 37 to 120 ppt, the total carotenoids production and beta-carotene also increased significantly, so that the amount of carotenoids reached from 0.8 to 4.67 μg/ml. Beta-carotene also increased from 0.03 to 0.17 mg/ml. Based on this information, optimal growth and accumulation of economic pigments in microalgae Cyanothece sp. can be obtained at salinity 90 to 120 ppt.

The aim of this study was to evaluate the effect of hydroalcoholic extract of Aloe vera plant by bath therapy on immunological and blood parameters and control of saprolegniasis in rainbow trout (Oncorhynchus mykiss). After two weeks of adaptation, fish with an average weight of 22±0.27g were randomly divided into 6 experimental treatments with three replications (30 fish repetitions each). After scaling from the caudal fin, the fish were infected with 3×105 zoospores of Saprolegnia parasitica per litter for 4 hours. After that, four treatments received 50, 100, 150 and 200 mg/L Aloe vera hydroalcoholic extract for one hour daily for one week. The other two treatments belonged to the positive control groups (with infection and without Aloe vera treatment) and the negative control group (without infection and without Aloe vera treatment). Evaluation of hematological and immunological parameters at the end of one week of bathing with the above concentrations (first week) and one week after cessation of bathing (second week) showed that hematological, biochemical and immunological parameters of rainbow trout (O. mykiss) treated with 100 mg/l Aloe vera hydroalcoholic extract was significantly increased. Also, at this concentration of hydroalcoholic extract of Aloe vera, minimal losses were observed, which was statistically significant compared to the control group. According to the results, treatment of rainbow trout with saprolegniasis with 100 mg of hydroalcoholic extract of Aloe vera per litter can improve immune function and increase their survival against saprolegniasis.

This study was conducted to evaluate the technical efficiency of Gilan seine fishing cooperatives. In this research, the data envelopment analysis method was used and the data of this research were collected by using a questionnaire from the cooperatives for the year 2017. The results showed that these cooperatives had about 93% technical efficiency on average. So, the cooperatives can have 7% more fishing without increasing their inputs. Also, about 46% of cooperatives are in a state of incremental returns to scale or scale economies and about 26% of cooperatives are in a state of decreasing returns to scale or scale diseconomies. In addition, this study identified the most important reference cooperatives as well as the possibility of reducing inputs for cooperatives that are not 100% efficient. In general, although the fishing cooperatives of Guilan province are in a favorable position in terms of technical efficiency, but, considering the amount of technical efficiency and returns to scale, it is better that the Fisheries Organization of Iran provide more support to cooperatives that are less efficient to become more efficient and reduce costs, and encourage more efficient and superior cooperatives.

The increasing use of carbon nanotubes has led to their synthesis and releasing into the environment, especially aquatic ecosystems. Therefore, it is important to study the effects of their ecotoxicity and their genotoxicity on algae as the first chain of the food web. In this study, the effects of single-walled carbon nanotubes with a diameter of 1-2 nm on green algae Chlorella vulgaris were analyzed. Treatments include: 0 (control), 12.5, 25, 50, 100, 150 mg/l were chosen to survey their effects on C. vulgaris at different hours. Cells number, chlorophyll a concentration and specific growth rate were measured. The results showed that cell density decreased, and there was significant difference between control and other treatments (p<0.05). The maximum and minimum number of cells in the control and 150 mg/l treatments were about 6.2×104 (after 48 hours) and 2× 104 cells/ml (After 72 hours) respectively. Increasing trend in chlorophyll a concentration was observed by treatment of 12.5 mg/l up to 96 after exposure.  After 72 hours, the maximum chlorophyll a concentration was recorded (0.175 μg/l). There was significant difference between control and other treatments (p<0.05). The specific growth rate at the treatment of 12.5 mg/l nanoparticles was the highest value equal to 0.055 after 96 hours, and decreasing trend of specific growth rate of control sample with other treatments was observed. According to DNA damage, treatmented cells were prepared by Alkaline single-cell gel electrophoresis method (comet assay), and stained with fluorescent dye. Microscopic images showed that damaged cells appear as comets composed of an intensively stained comet head and a tail of migrated DNA fragments. There was not sequence in untreated cells (control). Thus, single-walled carbon nanotubes induced DNA damage in algal cells.