مجله علمی شیلات ایران
سال سی‌ام شماره 2 (پیاپی 124، خرداد و تیر 1400)

This study was carried out to evaluate the qualitative status of chemical analysis including moisture, crude protein, crude ash, crude fat, NDF, (Insoluble fibers in neutral detergent) and ADF. (Insoluble fibers in acidic detergent), and the possibility of aflatoxin and mold contamination in fattening salmon feed used in fish farms in Fars province and fish feed supply factories. The obtained data were analyzed using SPSS software and Duncan test was used to compare the means of the data. The results showed that crude protein in feed GFT1 and GFT2 of factory No.2 had statistically significant difference (P<0.05) from other three factories. Only feed of a factory No. 2 provides the minimum amount of crude protein required for fish in these groups. The amount of crude protein in GFT3 and GFT4 related to factories 2 and 3 higher than that in factories 1 and 4 (p<0.05), but all factories have the minimum amount of crude protein needed by this group. The results of contamination of all samples of forage feed (GFT1, GFT2, GFT3, and GFT4) of fish farms and factories to aflatoxins and mold showed that the contamination rate is lower than the standard. In general, due to the different chemical composition of feed samples in fish farms, different feed supply factories and failure to meet the needs of fish at different ages, it is mandatory to continuous monitoring of feed produced in different factories and providing corrective guidelines to improve nutritional status of fattening fish.

The aim of this study was to investigate the changes in the bacterial quality trend (indicator bacteria) of water and its relationship with some environmental parameters around fish cages culture in the southern Caspian Sea region (Nowshahr-Mazandaran province). For this purpose, water sampling of the southern region of the Caspian Sea in the Tuskatok region of Nowshahr city in Mazandaran province took from January 2017 to December 2016 during the rainbow trout cage culture period at different distances cage (cage shade, 200 and 1000 m).The results showed that in the whole cage culture period, the maximum average of 18750 CFU/ml water bacteria was observed in the 200 m cage station before the cage culture period and the minimum average of 3250  CFU/ml water bacteria was observed in the 200 m cage station at the end of the cage culture period. The presence of total coliform and fecal coliform in water samples was recorded as 18.75 and 2.08%, respectively, and fecal streptococcus water was not observed in any of the sampling stations and in this situation, fish cages culture did not cause contamination. Maximum and minimum water temperature, pH, turbidity, saturation percentage and biological oxygen demand are 26.50 and 7.00 °C, 8.71 and 8.29, 19.71 and 0.52 NTU, 87 and 160, respectively. Percentage of 1.32 and 8.39 mg/l were recorded. Based on the principal component analysis (PCA), the results showed that the variables of pH and water temperature had the highest variance and the total count along with water turbidity in the third component showed a significant positive correlation (p<0.05). As a result, the proper slope of the area, the proper flow of water around the small-scale cages has reduced the microbial contamination in the shade of the cage compared to the stations outside the cage.

At the present study, phlorotannin content, antioxidant properties (DPPH free-radical scavenging and ferric reducing power) and inhibitory of polyphenoloxidase enzyme from Vannamei shrimp (Litopenaeus vannamei) in different extracts (first and ethyl-acetate) extracted from brown seaweeds Nizimuddinia zanardinii, Sargassum ilicifolium, Sargassum cristaefolium and Stoechospermum marginatum with methanol 100% and 70% were investigated. Among different seaweeds species, the highest amount of phlorotannin (13.21 mg PHG/g), DPPH scavenging (72.64%) and reducing power (0.96) were measured in the ethyl-acetate extract of N. zanardinii in methanol 100% treatment. Phlorotannin compounds including Eckol, Dieckol, Bieckol were identified by using of TLC in the ethyl acetate extract of N. zanardinii. The results showed that phlorotannin content and antioxidant activity varies in different species depending on seaweed specie, type of extract and type of extraction solvent. The amount of Vannamei shrimp polyphenoloxidase inhibition was different between various extract and seaweeds; and the highest amount of inhibition (71.11%) was measured in the ethyl-acetate extract of N. zanardinii. The results of present study showed that seaweed extracts with high amount of phlorotannins content could be considered as natural and safe polyphenoloxidase enzyme inhibitor.

Lake of the Persian Gulf Martyrs has been constructed in the northwest of Tehran in 22 urban areas, which in addition to creating a recreational-tourism environment, has caused an increasing economic value to the adjacent lands. The declining water quality of the lake and the increasing abundance of rough and invader fishes such as Prussian carp (Carassius gibelio) and Sharpbelly (Hemiculter leucisculus) are a threat for ecosystem of the lake. In order to control these fishes, pike (Esox Lucius) as a predator was released in the lake. After introduction of pike was studied its diet and growth, and the changes of invasive fish population in 2018-2019. Lincoln–Petersen method showed that the population of Prussian carp was decreased from 20,000 to 8,300 individuals in lake. CPUE showed that population of Sharpbelly has been reduced from 712,000 to about 3,000 individuals in the lake. Using Jolly-Seber method, population of Sharpbelly from the lake shore did not change much during the study period. The population of Pike was estimated at 575 that with continuous feeding of invader fishes had a weight gain of 3.7±6.1 grams per day. The occurrence percentage of Prussian carp was more than other preys; Sharpbelly and topmouth gudgeon (Pseudorasbora parva). Due to the increase in the size of the Pike, the small fish in the lake do not have much nutritional benefit for the pike and in the current situation, only the Prussian carp fish are fed. In order to better control of the invader fish, the use of small-sized predatory fish seems necessary.

The present study was objected to determine of (Qu) on of silver nanoparticles (AgNPs) in gill, brain, and spinal cord tissues of . To this end, the fish (n= 120; average weight= 200±15 mg) were assigned into 4 treatments (in three replicate) and fed with experimental diets containing following additive for 40 days: negative and positive controls (without additive), low dose of Qu (L.Qu, 200 mg kg-1 ), and high dose of Qu (Qu, 400 mg kg-1 ). After feeding trial, the fish were exposed at LC25 silver (0.15 mg L-1). The results of this study showed that AgNPs induced histopathological changes of edema, aneurism, epithelial lifting, , hypertrophy, fusion of lamellae, necrosis, hyperplasia, mucous secretion, clubbed tips, and curvature in gill tissue, and blood congestion in and spinal cord tissues. The highest severity of these histopathological changes observed in the positive control when compared to (p<0.005). treatment reduced the severity of these changes about 25-35% when compared to (p<0.005). The fish fed Qu illustrated the lowest severity of changes (p<0.005). Furthermore, L.Qu and Qu treatments decreased the severity of blood congestion in brain tissue (p<0.005). , taken together, could be as a preventive and therapeutic strategies to ameliorate toxicity of AgNPs.

The spatial salinity patterns which give a picture of the area affected by eutrophication and trophic status changes at the ecosystem. The aim of this study was to determine the area affected by freshwater eutrophication using trophic level (TRIXcs), the risk of eutrophication (UNTRIX) and the nutrient-salinity scatter diagram. Also, the data of the present study are compared with previous year of studies. This research was conducted during 2018 to 2019 in eight transects and at 5, 10 and 30 meter depths of Iranian coasts of southern Caspian Sea. The results showed that mean seasonal changes of TRIXcs and UNTRIXcs were 4.94-5.59 and 3.57-4.17, respectively, which the highest trophic level and risk of eutrophication was observed in summer season. In addition to, trophic level (TRIXcs) risk of eutrophication (NUTRIX=4.30) of near the coast (5m depth) were high. Mean of TRIXcs and UNTRIX between different regions (western, middle and eastern) were not significant. In the present study, the maximum amounts of ammonium and soluble silica near the west coast were recorded in Anzali transect and also under the influence of the largest river Sefidrud in the southern shores of the Caspian Sea, but the points with maximum NOx and phosphate values were observed in the east (Amirabad and Bandar-e-Turkmen transects). The nonlinear relationship between NOx, NH4, DIP and DSi with salinity indicates that river flow and water mixing were affected nutrient concentration and changes of trophic levels in the study area.

This study aimed to identify the effect of environmental conditions on the diversity and abundance of polychaetes in the southern shores of the Caspian Sea in Guilan, Iran. Sampling of seasonal sediments was done (June 2017 - May 2018) in 4 stations and three depths of 1, 5 and 10 m with the help of a Van Veen grab sampler with cross section of 225 cm2 and three replications. Temperature, salinity, pH, dissolved oxygen, suspended solids and organic matter were recorded at each station. A total of 2711 polychaetes belonging to 5 species, 5 genera from 3 families were identified. The highest abundance was related to H. kowalewskii (39%) and the lowest abundance was related to H. invalida species (3%). The mean density in the four seasons of spring, summer, fall and winter was 67.66, 81.25, 48.66, and 28.33 worms per m2, respectively. The highest species diversity was 2.16 species per square meter and the biomass of 62.75 mg/m2 in spring and the lowest was in winter. The highest density, diversity and biomass were 80.41 worms per square meter, 2.33 species per square meter and 70.83 mg/m2 on the shore of Chamkhaleh, respectively; and the lowest were 16.83 worms per square meter, 1.5 species per square meter, and 31.41 mg/m2 on the shore of Chaboksar, respectively. The highest density, diversity and biomass were 127.87 per square meter, 3.68 species per square meter and 107 mg/m2 at a depth of 10 meters, respectively. The correlation results showed that among environmental factors, only organic matter had a direct significant relationship with species diversity. Density had a significant direct relationship with temperature and organic matter. Other factors did not show a significant relationship. The results of stability level of different species in the southern shores of the Caspian Sea (Guilan province) showed that N. diversicolor and H. kowalewskii species exist temporarily and other species randomly.

The catch of the sturgeon has declined severely in the last two decades in the Iranian waters of the Caspian Sea. One of the methods for restocking and rehabilitation of the sturgeon stock, is releasing fingerlings and juveniles fish into the rivers leading to the Caspian Sea. In the present study, in order to a quantitative and qualitative evaluation of the sturgeon fingerlings released into the Sefidrood River, which included: stellate sturgeon (Acipenser stellatus), Persian sturgeon (Acipenser persicus) and Ship sturgeon (Acipenser nudiventris), growth indices, weight frequency percentage, growth rate, condition factor, average daily growth and survival percentage of released juveniles were studied during 2017-2018. The total of 1865506 fingerlings of sturgeon released in 2017 from Shahid Dr.Beheshti Sturgeon Restoration and Genetic Conservation Center which comprised Persian sturgeon with 69.3% and the average weight of 2.3±1.01 g, stellate sturgeon with 23.4%  and the average weight of 2.34±1.06 g, and Ship sturgeon with 7.3% and the average weight of 5.61±2.56 g, and  the  total of 1609448 sturgeon fingerlings released in 2018 which included Persian sturgeon with 68% and the average weight of 1.65±0.75 g, stellate sturgeon with  25.5%  and the average weight of 2.68±1.4 g, and Ship sturgeon with 6.5% and the average weight was 11.6±4.34g. Based on the Pearson correlation analysis, there were a negative correlation between the number of culture days for two species of Persian sturgeon and stellate sturgeon released during the years 2017-2018 in Sefidroud River and growth coefficient, condition factor, specific growth rate and daily growth rate at the end of rearing period (p<0.05). Also, the mean daily growth rate and specific growth rate of Persian sturgeon and stellate sturgeon fingerlings in 2017 were significantly higher (p<0.05) compared to 2018 and even in stellate sturgeon were higher than in Persian sturgeon.

Comparison of profitability of different densities of Litopenaeus vannamei post larvae stocked in earthen ponds, in two 20-hectares shrimp farms base on semi-intensive and intensive culture system located in Delvar site in Bushehr province was performed, in 2019. The ponds with area of 1.2 and 2 ha. In semi-intensive farm was stocked with 17, 30 and 33 42 PL/m2, respectively. In intensive farm the pond was stocked 20, 30 and 40, 50 PL/m2 in the pond of 1.2 and 2 hectare, respectively. The result showed that the cost of feed (59-62%) was the highest cost and the cost of energy included the lowest cost in shrimp rearing. Production in semi-intensive system was more economical, despite of total biomass were produced in intensive system approximately 1.6 times more than semi-intensive. However, total cost of shrimp production was 29 thousand Rials/kg while the net profit was in semi-intensive and intensive culture system 19 and 18 thousand Rials/kg, respectively. According to the obtained results, the most profitable density is 33 and 40 pieces/m2 in 1.2 and 2 hectare, respectively.

This study was conducted to examine the effect of diets containing various amounts of soybean meal and Phyzyme® XP on hematological indicators and serum liver enzymes in Caspian trout (Salmo caspius) with the average weight of 148.1±1.98 g for 85 days. For this purpose, 240 pieces of juvenile Caspian trout were randomly distributed in six treatments, including control treatment (basic diet) and five experimental treatments including  treatment I (basic diet + 2000 IU/kg diet of Phyzyme® XP), treatment II (basic diet containing 20% soybean meal), treatment III (basic diet containing 20% soybean meal + 2000 IU/kg diet of Phyzyme® XP), treatment IV (basic diet containing 40% soybean meal), and treatment V (basic diet containing 40% soybean meal + 2000 IU/kg diet of Phyzyme® XP) with two repetitions per treatment (20 pieces of fish per repetition). The largest amounts of red blood cells and hematocrit were observed in treatments I and III, respectively, which was significantly different only from treatment IV (p<0.05). The largest amount of hemoglobin was observed in the control treatment, which was significantly different from other treatments, except treatment I (p<0.05). The highest number of white blood cells was observed in treatment III, which was significantly different from other treatments (p<0.05). The lowest serum levels of the liver enzymes, including lactate dehydrogenase and alkaline phosphatase, were recorded in treatment I and control treatment, respectively, which showed no significant difference from treatments II and III (p>0.05). Besides, serum levels of these enzymes in treatment V showed no significant difference from treatments II and III (p>0.05). Therefore, according to the results of the present study and no significant differences in the values of most of the parameters between the control treatment and treatment V, it is recommended to replace 40% soybean meal containing 2000 IU/kg diet of Phyzyme® XP, instead of fish meal, in order to achieve an affordable diet without any negative impact on health parameters in the Caspian trout.

In the present study, the effect of Pullulan coating with watercress extract on the quality and shelf life of fresh beluga sturgeon fillet stored in a refrigerator over a period of 16 days was investigated. First, the watercress extract was extracted by ultrasound and soxhlet (solvent) method and the amount of phenolic compounds and antioxidant activity of the extract (DPPH free radical activity test) were determined. The values of phenolic compounds for soxhlet extract were equal to 586.53 mg gallic acid per gram of dry weight and for ultrasonic extract was 879.57 mg/g dry weight and the antioxidant properties of watercress extracted by ultrasound were significantly higher than soxhlet method (p<0.05), so ultrasound extracts were added to the pullulan coating. Then, 4 treatments were included: control, pullulan coating, pullulan coating + watercress extract 500 ppm, pullulan coating + watercress extract 1000 ppm were analyzed by biochemical parameters such as peroxide value (PV), thiobarbithic acid (TBA), free fatty acid (FFA), total volatile base nitrogen (TVB-N) and pH). The results showed, natural preservation delayed chemical spoilage in compared with control treatment (p<0.05). According to the results pullulan coating + watercress extract 1000 ppm significantly retarded lipid oxidation by decreasing peroxide value and thiobarbituric acid production in the samples and it had the lowest total volatile basic nitrogen and pH (p<0.05). The control treatment had only the allowed chemical range for up to 6 days, but the treatment containing pullulan coating + 1000 ppm extract had the allowed values until the end of the storage period. The final conclusion showed that the coating of pullulan with watercress extract could act as a natural antioxidant, delaying chemical degradation and prolonging the shelf-life of fish fillets.

Acanthobrama urmianus is an endemic species of Cyprinidae family in the Urmia Lake basin and important for ecological and sport fishing. The main purpose of this study was to investigate the relationship between the fecundity with length, weight and age in two rivers of Mahabadchai and Siminerud and sampling was carried out from December to June using cast-net and gill-net. The result of the study on 107 female fish specimens from maturity stages 4 and 5 showed that the absolute fecundity of this fish is 1567 to 27228 (11954.3±6991.9) eggs with a diameter of 0.35 to 1.42 and the relative fecundity is 87.9 to 633.9 with an average of 282.6±120.7. Also, with increasing age and size of the fish body, the absolute fecundity increased. Between the absolute fecundity and the total length of equation F= .0034TL 3.545 (r2=.789) and between the absolute fecundity and the weight of the equation F=23.272W1.665 (r2=.766) obtained. The results showed that the rate of fecundity in Mahabadchai in the constant length range was less than Siminerud River.

Investigating the quantitative and qualitative characteristics of resources is one of the key pillars of sustainable development and sound management practices in various fields of environment, fisheries and agriculture. The impact of pollutants on organisms varies according to their type and volume of input. These effects at the highest levels cause the destruction of the fauna and flora of the area and in small amounts eliminate the resistant species. In recent years large-scale invertebrates inhabit sediments reflecting the effects of environmental contamination as a change in their diversity or density, which is why more attention has been paid to biological monitoring studies. In each half-line, sediment samples were taken from the surface layer at 3 different depths of 5, 10, 15 m. Sediment samples were analyzed by ICP-OES (Varian Vista -MPX model) according to ASTM D5258-92, 2013. Shannon Wiener Index, Species Richness Index and Margalef Index were used to assess the Diversity, Dominance and Richness of Macrobentic in the study area. On average, the lowest Shannon Wiener Index of Fereidonkenar Port in spring (0.63), in Summer (0.25), in Autumn (0.54), in Winter (0.37). The lowest Margalev Index of Fereidonkenar Port in Spring (0.45), in Summer (0.25), in Autumn (0.46), in Winter (0.28) was achieved. In the present study, were significantly  higher (p<0.05) compared to Shannon and Margalph Index. Also, the result  shown were different temporal and spatial variations in the structure of Benthic Communities and  stress and contamination were moderate.

An experiment was conducted to evaluate the effect of biofloc system on water quality, growth performance, immunity and body composition of Nile tilapia at different stocking densities. Fry (3.2±0.05 g) stocked in 500 and 1000/m3 in biofloc and clear water system (as control) in three replicates and reared for 50 days. Results showed that the lowest TAN and highest nitrite and nitrate were observed in BFT treatments. Total suspended solid, floc volume and bacteria increased by increasing stocking density. Maximum final weight (12.9g), SGR (3.21 %/day), survival (100%) and the best FCR (0.91) were obtained in BFT (500/m3). There were no significant differences in survival among treatments (p>0.05). Lysozyme, immunoglobulin and catalase of fishes in the biofloc treatments were significantly (p<0.05) better than control. Proximate analysis revealed that protein and lipid content of fishes in BFT were slightly higher than control groups but these differences were not significant. It seems that although fishes in BFT 500/m3 statistically showed better indices than others but due to small differences in growth indices and feed conversion ratio in one hand and no difference in survival rate between 500 and 1000/m3. On the other hands, the study suggests the stocking density of 1000/m3 for larviculture of tilapia in biofloc system to use water and equipment more efficiently.

In recent years the incidence of algal blooms caused by Nodularia to become one of the serious problems and is threated life of aquatic organisms in the southern Caspian Sea. Nodularia is Blue - green algae (cyanobacteria phylum) and due to production of nodularin toxin is importance. In this study, the first, three species of Pseudomonas including Pseudomonas aeruginosa, P .putida and P. fluorescens were isolated from Tajan river estuary and identified using biochemical tests and compared to standard species. The trend of Nodularia spumigena biomass (log 5) and Pseudomonas species (log 7 and 8) were examined in 30 treatments for 10 days in aquarium scale. The results showed that the decline trend of Nodularia in P. aeruginosa and mixed species treatments were better than other treatments and log 8 of bacterium was also more inhibitory effect than to log 7. Similar results were observed in double layer on agar medium and latter treatments had algaecide effect on nodularia. However, P. putida and P. fluorescens treatments had algaestatic properties. The conclusion showed that different strains of Pseudomonas are able to reduce the population of algae N. spumigena in aquarium scale and the results observed in combination treatment were better than other treatments.