فصلنامه شیلات
سال هفتاد و ششم شماره 1 (بهار 1402)

It is important to study and investigate exotic species to protect their stocks. This study was carried out to investigate the morphological change in Chelon saliens populations from southern basin of the Caspian Sea. For this purpose, during 2020-2021, by beach seine nets, 238 specimens were collected from seven costs including Astara (35 samples), Talash (45 samples), Bandar Anzali (50 samples), Kiashahr (33 samples), Langaroud (15 samples), Chaboksar (40 samples) and Sari (13 samples). After imaging the lateral view of the samples, some 14 landmark-points were defined and digitized on the two-dimensional images. The body shape data after generalized procraust analysis were exposed to statistical analysis including principal component analysis (PCA), canonical variate analysis (CVA) and cluster analysis (CA). Also, the deformation patterns of each population related to consensus shape of the populations in the deformation grids were illustrated. The results showed that there is a significant difference among the studied populations in terms of morphology. The highest Mahalanobis and Procraust distances were obtained in Langaroud and Sari, respectively. The main morphological differences were related to the position of the mouth, head size, body depth and caudal peduncle length, indicating the high morphological flexibility of this exotive species in adaptation with different habitats of the Caspian Sea basin.

The present study was conducted to compare the growth, nonspecific immunity systems and stress of Oncorhynchus mykiss in three concrete agricultural water storage ponds, consisted rectangular (Treatment 1), round (Treatment 2), and octagonal (Treatment 3) shapes in a trout farm. Density of 20 fish/m3 (3 repetitions) and water flow D.B of 2.5 lit/sec, were run for each experimental unite and fish cultured for 5 months. According to the results, higher dissolved oxygen and reduction in sludge and NH3 production recorded in water in treatment 3 compared to other treatments (p≤0.05). The highest and lowest final individual weight measured in treatment 3 (434.21±22.16 g) and treatment 1 (349.41±18.91 g), respectively (p≤0.05). The values of RBC, hemoglobin, hematocrit, MCV, MCH and MCHC were not significantly different among treatments (p≥0.05). The highest and lowest levels of stress indicators (glucose and cortisol) and nonspecific immune systems of fish (number and differential percentage of WBC, plasma complement activity, immunoglobulin, total protein and serum lysozyme) belonged to treatments 1 and 3, respectively (p≤0.05). The results showed that, treatment 3 has better self-purification status than the other treatments, and has a positive and significant effect on growth, nonspecific immune systems and stress in rainbow trout. Therefore, using rectangular shape of pond for culture of trout can be promoted among the farmers of Sistan region in the direction of resistance economy and more economical production.

The present study aimed to assess the performance of generalized linear model (GLM) and random forest (RF) model in predicting Caspian Kutum (Rutilus frisii) catch distribution. Caspian Kutum catch per unit of effort (CPUE) data was used as the response variable. Remotely-sensed data of five environmental parameters were used as model predictors as well, including daily sea surface temperature (SST), chlorophyll-a concentration (CHL), aerosol optical thickness (ASL), particulate organic carbon (POC) and particulate inorganic carbon (PIC) concentrations. The coefficient of determination (R2), mean absolute error (MAE), and root mean square error (RMSE) scores were used as measures of model performance and accuracy. The best fitted GLM had only Log(PIC) and POC as significant parameters, while the RF model contained all predictors. RF showed higher explaining potential compared to GLM (RF: R2=0.47; GLM: R2=0.053). Also, higher accuracy was observed using RF (MAE=972.4; RMSE=1326.1 (kg/hour.seine)) than GLM (MAE=1328.7; RMSE=1465.6 (kg/hour.seine)). ASL (33.31%) and CHL (28.87%) were parameters with the highest and lowest relative influence in the RF model. Based on the results, random forest modelling is suggested as a practical technique for predicting fish catch distribution.

This study was conducted to investigate the shape and morphological characteristics of otolith in some of economic fishes in Anzali wetland and the possibility of using these characteristics to identify species. In this study, Sajita otolith was extracted from 5 species of fishes and their morphological characteristics were investigated. These species belong to the families of Esocidae (Esox lucius), Leuciscidae (Abramis brama), Xenocyprinidae (Hypophthalmichthys mollitrix), Mugilidae (Chelon saliens) and Percidae (Sander lucioperca). The species were selected and their biometric characteristics and their otoliths were recorded and extracted. Then, the shape of the otoliths was studied and the biometric characteristics of the left and right otoliths of each sample were recorded by measuring their length, width and thickness. Also, the size, elongation and thickness indices of otolith were calculated and the relationship between the parameters was investigated. The results showed that the shape of otolith among these species and even species belonging to one family were different. The highest weight, head lengths and otolith lengths were not observed in the largest sample. There was a significant positive relationship between total lengths and otolith lengths in Chelon saliens and Sander lucioperca. Also, a positive and significant relationship was observed between the weight and thickness of otolith in Chelon saliens. So, the morphology of otoliths can play an important role in the taxonomy of fish.

There is limited information about the relationship between abiotic and biotic variables of the shrimp/prawn stocks in the Persian Gulf. Consequently, the effect of some environmental factors, including temperature, salinity, and depth, on the abundance of two commercial species, Jinga shrimp (Metapenaeus affinis) and green tiger prawn (Penaeus semisulcatus), on the coasts of Khuzestan Province were assessed in the present study. For this purpose, regression, and RDA, as an ordination method, were employed to investigate the impacts of the depth, temperature, and salinity on the capture per unit effort (CPUE). The maximum CPUE for M. affinis in the western region (Life’h- Buseyf) was 18.75kg/h at a depth of 5m, 28.5°C and 40ppt salinity. It was obtained the 2.03kg P. semisulcatus per hour from the eastern region (Bahrkan) at 22m, 32°C, and 40ppt. The results of RDA revealed that the changes in CPUE have a statistical relationship with environmental variables. So that this relationship is direct for Penaeus semisulcatus and inverse for Metapenaeus affinis, and the sea depth was the most significant factor in fishing both shrimp/prawn species. The selection of the leading variables has also confirmed these results. Additionally, the temperature was recognized as the subsequent influencing factor, and the salinity variable had no significant effect on the CPUE of species. Regression models showed only a significant impact of depth on the CPUE of Penaeus semisulcatus, and the capture of Metapenaeus affinis lacked any statistical effectiveness of environmental variables.

This study investigated the effects of different levels of vitamin E on growth performance and blood indices of Caspian trout (Salmo caspius) juveniles. Six diets with different levels of vitamin E including 0, 10, 20, 40, 80 and 160 mg kg-1 were prepared. The actual amounts of vitamin E in diets were determined using high performance liquid chromatography and were as follow: 4.9, 8.6, 17.4, 35.4, 78.8 and 137.0 mg kg-1. In total, 360 fish (initial mean weight of 9.32±0.34 g) were randomly distributed in 18 cylindrical tanks (20 fish per tank) with the working volume of 900 L. Each tank was randomly assigned to each of the experimental diets with 3 replications. The fish in each tank were fed with the respective diets for eight weeks and finally their growth indices and blood parameters were evaluated. The results showed that the final weight, daily growth coefficient and feed efficiency ratio of fish increased linearly (p<0.05) and quadratic (p<0.05) with increasing the vitamin E levels and reached the highest value in fish fed with 78.8 mg kg-1 vitamin E. Significant linear (p<0.05) and quadratic (p<0.05) increases in red blood cells (RBCs) and white blood cells (WBCs), hemoglobin content and hematocrit percentage were also determined by increasing in dietary vitamin E concentration. The percentage of neutrophils in fish blood reached the lowest level after feeding with the highest amount of vitamin E (137.0 mg kg-1 vitamin E) while the highest percentage of lymphocytes was recorded in fish fed with 78.8 mg kg-1 vitamin E. The findings of the present study showed that vitamin E could improve the performance and blood parameters of Caspian trout. The best level of vitamin E was estimated to be 82.16 mg kg-1 based on the daily growth coefficient and 102.98 mg kg-1 according to WBC number.

Most fishermen use traditional methods to identify areas with fishing potential. Increasing demand for fish and the need to exploit marine resources in a cost-effective manner and reduce human activities have made the introduction and application of new methods important considerations. The use of remote sensing in fishing leads to successful fishing and reduces the cost of fishing and human activities. In this research, we have tried to identify the distribution of Yellowfin tuna in the Oman Sea using Remotely Sensed system and draw a map of their possible presence. For this purpose, the distribution patterns of tuna fishes were studied through catch data and monthly remotely sensed data (sea surface temperature, chlorophyll-a, sea surface heights, salinity and wind speed) for the years 2016 and 2017 in the Oman Sea using GIS and multi-criteria evaluation. The results showed use of remotely sensed data to determine the spatial and temporal distribution patterns of Yellowfin tuna is more than 70% accurate. By studying, the output of the catch distribution map and the test data was determined the proposed model is of optimal power for identifying Yellowfin tuna. On this basis, it can be mentioned that remotely sensed data could show potential fishing zone with a least error. Therefore, in future studies, the use of remotely sensed data for location of fishing and fishermen guidance is suggested, Also the results of this research could help fishery managers to ecosystem fisheries based on management and reducing the fishing effort for fish finding.

The aim of this study was to optimize the extraction conditions of hydroalcoholic extract of Tetraselmis suecica under 50, 70 and 90°C, duration 20, 70 and 120min and dry matter to solvent ratio of 10, 20 and 30 mL/g.  The effect of adding hydroalcoholic extract of Tetraselmis algae at concentrations of 0, 350, 550 and 1000ppm to Thunnus albacares oil were investigated during 56 days of storage as well. The highest percentage of free radical scavenging of 69.19% was measured at 120min, extraction temperature of 50°C and ratio of 30 mL/g solvent to dry matter. The hydroalcoholic extract of Tetraselmis contained 25.15 mg/g GAE phenolic compounds and 0.85±0.05mg/g QE flavonoid compounds, respectively. The highest antioxidant power was measured at a concentration of 1000ppm of hydroalcoholic extract of Tetraselmis algae (81.14±0.16 %) which was higher than the antioxidant power of BHT with a concentration of 0.01% (60.24±0.18%). The control treatment had the highest and the yellowfin tuna oil treatment containing 1000ppm hydroalcoholic extract of Tetraselmis had the lowest level of oxidation indices (peroxide, thiobarbituric acid and p-anisidine). The results of kinetic experiments, protective factor, antioxidant power and induction period (IP) in all three concentrations of hydroalcoholic extract of Tetraselmis were higher than control and BHT. The results showed that treatments containing three concentrations of 350, 550 and 1000ppm hydroalcoholic extracts of Tetraselmis algae had a higher protective factor and antioxidant power compared to BHT and this extract could replace synthetic compounds.

This study was conducted to understand the health status of Karaj River ecosystem as one of the most important rivers in Iran, the physicochemical parameters, toxicity and saprobic indices were analyzed due to sampling from 12 stations in 2021. Identification of benthic organisms and calculation of biological value was performed. Qualitative status, toxicity analysis, measurement of PAHs along with statistical analysis were performed as well. According to the results, the general water quality index decreased in downstream except for the branches. Toxicity had fluctuating and generally decreased from upstream to downstream. The biological value index had the highest rate in Chamran Park and the lowest recorded in Haft Cheshmeh branch. In terms of saprobic index, the river categorized in Oligosaprob, β-mesosaprob and α-amesosaprob classes. Upstream stations had favorable status compared to downstream in both cold and warm seasons. Karaj basin subdivision maps were prepared based on the Munich method, IRWQIsc index and the combination of saprobi map, BOD and land use in the region. The results of the analysis confirmed the important role of human activities in river water quality, especially in rural and garden uses, and in the next stage, roads. From upstream to downstream, the number of pollutant sources has increased and their roles were evident. Development of rural areas negatively increased BOD and benthic index. Therefore, it is necessary to monitor and treat wastewater, to issue the environmental standards for agriculture activities and groundwater uses, as well as deal with violators with the aim of conserving the river.

Regarding the superior role of grass carp (Ctenopharyngodon idella) in aquaculture industry, this study was conducted to evaluate the effects of catching and transportation on stress responses and hematological parameters of 2 years old grass carp with an average weight of 1.10±0.23 kg. For this purpose, the mentioned indices were measured before catching (control), immediately after catching, after transportation to the market and 2, 6 and 24 hours post arrival of fish to the market. Cortisol, glucose and lactate levels increased immediately after catching to 6 hours after catching and decreased significantly at 24 hours after catching but did not reach the initial level. In hematological indices, the mean corpuscular volume, mean corpuscular hemoglobin, the number of white blood cells, lymphocyte, neutrophil and monocyte were significantly different among the times (P<0.05). The number of red blood cells, hematocrit, hemoglobin, and mean corpuscular hemoglobin concentration did not show significant different among fish (P<0.05). The results of this study showed that due to the effects of catching and subsequent transport stress on physiological status of grass carp, in order to supply fish with worthy health and quality to the market, it is necessary to provide optimum methods to reduce the stress.

Use of effective substances to inhibit bacteria in the aquatic environment due to indiscriminate and long-term use of antibacterial substances such as antibiotics seems to be necessary. Polyethyleneimine (PEI) is a synthetic polymer with antibacterial properties and chemical formula (C2H5N)n which consists of many side groups of NH2, the use of this polymer due to its antibacterial property in binding with different substrates can be considered. Among these substrates that are widely used in aquaculture is Zeolite. In this study, zeolite was coated with PEI polymer with two concentrations of 1 and 2 mg/l and after confirmation by Fourier transform infrared spectroscopy (FTIR) analysis is placed inside the filters. The function of the filters was determined by measuring the bacterial load of the water, survival and growth of post larvae. The results showed that negative control, treatment of zeolite modified with concentration I, treatment of zeolite modified with concentration II of PEI polymer, treatment of natural zeolite and positive control at 104 CFU/ml Aeromonas hydrophila bacteria on the 10 days of the experiment were grew 50, 125, 125, 348 and 380 colony/100 ml in TSI medium, which shows a decrease of 67.1% of the bacterial load in both modified treatments with concentrations I and II of PEI polymer compared to the positive control. Also, the survival rate of postlarvae showed a significant increase in the treatment of modified zeolite with concentration I and II compared to the negative control (P<0.05). However, there was no significant difference between treatments in dry weight and length (P>0.05). Finally, after summarizing and comparing the results of this study with others, it can be concluded that the use of zeolite modified with PEI polymer in the filtration system of giant freshwater prawn Macrobrachium rosenbergii post larval rearing tanks has a potential effect on bacterial reduction of Aeromonas hydrophila bacteria.

The aim of this study was investigation of some reproductive traits of Aphaniops hormuzensis in the Mehran River. Of 664 recorded individuals, 290 specimens were male (43.67%), and 374 specimens were female (56.32%). The sex ratio (females/males) was 1.28:1 (P<0.05). The smallest and biggest size of fish were 19.8 mm and 45.7 mm, respectively which belonged to female. Both sexes showed negative allometric growth. Fecundity ranged from 4 (total length 22 mm, weight 0.36 g) to 73 (total length 45.7 mm, weight 2.3 g) eggs per individual. The highest value of GSI obtained in April (14.32±5.18). This fish had actively breeding during March to October with a remarkable peak in spring. Asymptotic length (L∞), growth rate (k) and t0 were 45.69 mm, 0.73 per year, and -1.19 for males, respectively and 47.05 mm, 0.72 per year and -1.2 for females. The obtained results of this study can be used for determining the strategies for further conservation and management policies of this species with the aim of preserving the biodiversity.