جستجوی مقالات مرتبط با کلیدواژه "h" در نشریات گروه "شیلات"

This research aimed to investigate the effect of gamma-aminobutyric acid supplementation on the growth and survival indicators of rainbow trout fry kept at high density, for this purpose, 585 fry with an average weight of 5 ± 0.03 grams in 5 experimental treatments with High density (129 pieces in 69 liters) and a negative control group with normal density (69 pieces in 69 liters) were included. The test treatments included a positive control group, treatments 100, 200, and 300, which were fed with gamma-aminobutyric acid supplement sprayed to the commercial diet at the rate of 0, 100, 200, and 300 mg/kg, respectively during 7 weeks, . At the end of the breeding period, the growth indices including weight gain, food conversion coefficient, specific growth coefficient, specific growth rate, condition factor, protein yield ratio, and survival percentage were examined. In all the growth indices, there was a significant increase in the feeding groups. Gamma-aminobutyric acid supplement compared to the negative control group was observed, the highest of which was related to the treatment of 300 mg of GABA supplement (P < 0.05). The lowest food conversion factor among the experimental treatments was related to the 300 mg group, which had a statistically significant difference with the positive control group (P<0.05, no deaths were observed in any of the groups. The results showed that adding a gamma-aminobutyric acid supplement to the diet of rainbow trout raised in high density moderates the negative effects of stress resulting from high density on growth indicators and improves these indicators.

The aim of this study was to investigate the effect of adding cottonseed meal and a mixture of organic acids to the diet on growth parameters, economic justification, and nitrogen and phosphorus retentions in rainbow trout. For this purpose, six triplicate treatments consisting of six diets were considered in a 3 × 2 factorial design, where two levels of cottonseed meal (0% and 15%) and three levels of organic acid mixture (a mixture of lactic acid, citric acid, and potassium sorbate in equal proportions) at 0%, 0.5%, and 1% were added to the diets. A total of 270 rainbow trout with an average weight of 14.0 ± 0.35 g were stocked in 18 aquaria containing 40 L of water, with a density of 15 fish per aquarium. The above diets were offered to the fish for 8 weeks at a daily rate of 3 to 4 % of biomass. The aquariums were equipped with a semi-closed system including aeration, physical filter, biological filter, and UV filter, with a daily water exchange of 30% during the experimental period. After the feeding trial, sampling of the fish muscle was conducted. The results of this study showed that adding cottonseed meal to the diet had no significant effect on final weight, fish production per unit volume of water, or feed cost; however, it significantly reduced the growth rate and increased feed conversion ratio. Additionally, adding organic acids to the diet had no significant effect on fish growth parameters. The addition of cottonseed meal to the diet did not significantly affect the phosphorus and nitrogen content in the fish muscle; however, adding organic acids to the diet significantly increased the phosphorus content in the fish muscle. Overall, the results indicated that cottonseed meal could be used at a level of 15% in rainbow trout diet. Although this amount of cottonseed meal significantly reduces growth and increases feed conversion ratio, it does not have a significant economic impact on trout production. Furthermore, adding organic acids at levels of 0.5% to 1% to the trout diet, while having no positive effect on growth, efficiency, or feed cost, does increase the phosphorus content in the fish muscle.

This study was conducted to study the catch composition of Largehead hairtail (Trichiurus lepturus) hand and line and some biological characters of T. lepturus in northern waters of Oman Sea (Remin fishing port).  Sampling was done by hand and line used in the region by four motor boats each of which included 4 fishermen from February to May 2022. 6955 fish were caught which include T. lepturus, Sphyraena jello, Carangoides chrysophrys, Terapon jarbua, Strongylura strongylura and Otolithes ruber. Among them T. lepturus with 97.66% had the highest percentage and O. ruber with 0.01% had the lowest percentage of catch. The maximum and minimum total length of T. lepturus caught were 128 cm and 42 cm, respectively. The optimal size of T. lepturus was 85.63 cm and the infinite length was estimated at 131.13 cm. Also, the length of sexual maturity was calculated as 66.57 cm. The results showed 84.36% of T. lepturus were mature and only 15.64% had a length less than the length of the first sexual maturity

The purpose of this research is to estimate the amount of nitrogen output resulting from raising juvenile Huso huso (Linnaeus, 1758) in the proposed pens located on the southeast coast of the Caspian Sea using the nitrogen dynamics model. In this research, nitrogen excretion was measured by storing 30,000 juvenile Huso huso in 750 square cages, the end of which was connected to the graft (pen) at a depth of 2 meters during 7 months of rearing (June to December) with an initial weight of about 30 grams and The final weight was about 750 grams at the end of the period and the average food conversion ratio was 1.5 and the percentage of survival was 82%, and the production of about 18 tons of fish was estimated. The results showed that at the end of the breeding period, it can be expected that the total amount of nitrogen and phosphorus (inorganic) entering the sea will be 0.919 and 0.123 tons, respectively. According to the dynamic model, the nitrogen discharged into the sea at 20 meters from the cage is estimated to be 0.13 mg/liter and 0.01 mg/liter at 1000 meters, which indicates compliance with the minimum radius of 100 meters from each cage to the next cage. Is.

Due to the decline in the population of Caspian salmon (Salmo caspius) in the southern part of the Caspian Sea, the age and growth of this fish were studied in the Dohazar River in Tonekabon to improve conservation programs. In December 2018, 63 fish samples were collected using an electroshocker. Among these, 21 females and 42 males were captured, resulting in a sex ratio of 2:1, with a significant difference between the sexes (p<0.05). The length range of males and females was 7.5–18.5 cm and 6.5–21.5 cm, respectively, while their weight ranges were 3.99–65.5 g for males and 2.51–95.42 g for females. Age determination was conducted using scales. The age range of the population was from +1 to +5, with females distributed across 5 age groups and males across 4 age groups. The highest age frequency in all cases was in the 1+ and 2+year age groups. The von Bertalanffy growth equations for males and females were calculated as Lt = 230.462{1-exp(-0.327(t-(-0.240)))} and Lt = 300{1-exp(-0.213(t-(-0.139)))} respectively. The mean Monro index for the total sample was 2.26, with 2.23 for males and 2.28 for females. The study results show a significant decrease in the growth parameters of the species across all age groups. Both the growth coefficient and the asymptotic length of the species have decreased compared to previous years.

Global concern over the overfishing of elasmobranches is well known, with an increasing number of studies in various regions of the world. The Gulf of Oman, like other ecosystems, the increasing fishing fleet and fisheries are considered important factors affecting aquatic resources. This study aimed to assess CPUA and biomass of batoidfishes and also biomass variation in the Gulf of Oman during two last decades. Sampling was carried from October to January using research bottom trawler of “FERDOWS1”, into 8 strata from Bandar Abbas (strata J) to marine border of Pakistan (strata Q). Overall, 1743 samples of batoidfishes belonging to 15 species and 10 families were recorded. The results appeared minimum and maximum CPUA in strata L and P with 1651.5 and 34.7 kg, respectively. Also, minimum and maximum biomass were found in strata L (1341.7 tonnes) and N (16.1 tonnes). Examining the trend of changes in CPUA and biomass from 2004 to 2017 showed that, with the exception of strata L, there were decreasing trend in all other strata. The results of the present study make it clear that after the apex predators, the meso-predators are also under threat, and the future of the Gulf of Oman ecosystem and the stability of the food web require proper management for the sustainable preservation of resources of the food web.

In order to investigate the possibilities and solve the obstacles and problems of ornamental fish farmers, information was collected online by designing an electronic questionnaire. The results of the 66 investigated farms in the country showed that, on average, 14 species of freshwater ornamental fish are produced in each farm, and 10% of the farms produced more than 25 freshwater species in each farm, of which 9 species were oviparous—according to Friedman's test, Biomare, Tetra, and Tropical food brands had the highest demand and level of satisfaction among imported brands in Iran, respectively. The most important live food consumed in the ornamental fish industry is Artemia, which was reported as one of the most important challenges of Artemia in Iran, its high price with 66.2% and low hatch percentage with 58.5%. About half of the farmers did not have communication with universities and the Iranian Fisheries Organization to solve their problems. One of the reasons for visiting the university was to solve the problem of fish diseases, to increase the reproduction rate, and then to improve the quality of water and wastewater. For disease problems, the main priority of farmers was to consult with other farmers and refer to literature. Based on the results of the chi-square test, water restrictions, and water quality control, the quality of Iranian feed brands, the hire of experts and skilled workers, the lack of credit aids and bank facilities, the lack of suitable feed, and the final price, the lack of formation of a trade :union: council, the increase in the price of inputs and currency, and the lack of space for fish farming has greatly affected this industry in Iran.

The aim of this study was to determine the optimal salinity for rearing the juveniles of Starry Sturgeon (Acipenser stellatus) in enclosed environments. Sturgeon with an average initial weight of 54.11 ± 1.54 g were raised in 500-liter fiberglass tanks (average temperature 22.58 ± 0.14 °C)in a control group (freshwater) and two treatment groups (6  and 12 ppt) in 3 replicates for 60 days. They were fed with commercial feed (Faradaneh) twice a day. At the end of the rearing period, specific growth rate (SGR), weight gain (WG), condition factor (CF) and hepatosomatic index (HIS) in experimental fish (12 ppt) were significantly elevated compared to control fish (p≤ 0.05). Food conversion ratio (FCR), on the other hand, was significantly reduced in the experimental fish (p≤ 0.05). The survival rate of fish was 100%. Intestinal villi length and internal space were significantly elevated and reduced in 12 ppt salinity, respectively (p≤ 0.05). The results suggest that the optimal salinity at this point of Starry Sturgeon life is the Caspian Sea water salinity (12 ppt) which provides the conditions for introducing this species as a suitable species for rearing in enclosed environments in natural water resources. Considering that A. stellatus lives in waters with diverse salinities at different stages of its life, it is important to know the appropriate weight and salinity for releasing in order to increase the percentage of survival and improve growth.

AbstractThe study investigated the effects of substituting fishmeal with different levels of hydrolyzed protein on the serum biochemical composition and immune system of beluga (Huso huso) fry over a 48-day period. A total of 750 fish were randomly assigned to five groups: a control group (no hydrolyzed protein), three groups with varying levels of hydrolyzed protein (2.75%, 5.5%, and 8.25%), and a positive control group (commercial feed). The study found significant differences in glucose levels among the groups (P<0.05), with the control group having the highest glucose level. Treatment 2 had the highest total protein and lipid levels, which significantly differed from the other groups (P<0.05).  Liver enzyme levels (ALT, AST and ALP) did not vary significantly among the groups (P>0.05).  There were no significant differences in cholesterol levels (P>0.05). Regarding immune factors, treatment 2 exhibited significantly higher total immunoglobulin levels compared to all other groups except for treatment 3 (P<0.05). Lysozyme levels did not differ significantly between the control group and treatments 1, 3, and 4 (P>0.05); however, treatment 2 displayed the highest level. IgM and ACH50 activity did not differ significantly across all groups (P>0.05). In conclusion, replacing fishmeal with hydrolyzed protein at a concentration of 2.75% to 5.5% improved performance in blood biochemical and immune parameters of beluga fry when compared to the control group.

The aim of this study was to investigate the effect of in fall and winter on the hematological and serum biochemical factors of 3-4 years old great sturgeon in the penclture ) located in the Gorgan Bay (Caspian sea) and processing sturgeon center of Marjani for 6 months.  Huso huso individuals were anesthetized withclove powderand 5 mL of bloodwas sampling from a total of 15 great sturgeon specimens were apparentlyhealthy by caudal venous puncture each of the examined panes (3 pins)in different seasons.Blood was analyzed with routine method and standard formulas used in fish hematology. the results showed thatthere are no any differences between the mean corpuscular volume, cortisol levels and activity of Alanine aminotransferase enzyme in the different season(p>0.05).But, by examining other parameters, the highest WBCs number, Activity of aspartate aminotransferase and alkaline phosphatase enzymes in summer, the highest RBCs number, hematocrit concentration, total serum protein in spring, the highesthemoglobin concentration, the mean corpuscular hemoglobinand themean corpuscular hemoglobin concentration in autumn and the highest glucose levels in winter were observed, which were significantly increased in comparison with other seasons (p<0.05). Overally, based on these results, it can be rectified that temperature changes as a result of season transition may have an important role on Blood factors of Huso huso. As with the same ecological conditions, with changing the temperature of the environment, we will see different changes in the blood factorsin the Beluga.

In the issue of aquatic management and assessment of freshwater fish species, it is important to examine habitat preference and habitat suitability indices, because the presence of many species in an aquatic ecosystem indicates the suitable conditions of their habitat. Therefore, this study was carried out to investigate and preference habitat of Oxynoemacheilus zarzianus in the Sirvan River. Sampling was done from different parts of the river (regarding depth, width and etc.)  in 7 stations each with 3 repetitions and a total of 21 stations. Sampling was performed along 30 m at each station against the direction of the river velocity, from the downstream of the river to the upstream. Ten environmental factors including pH, temperature, total dissolved solids, electrical conductivity, Altitude, depth, river width, velocity, and bed slope were measured. The results showed that the highest and lowest total SI values ​​for studied species were obtained for the altitude (0.237) and river width (0.1), respectively. The results showed that the highest abundance and presence of O. zarzianus were in places with gravel beds, which probably preferred these places to avoid predators. The value of the total suitability index also showed that this river is not a suitable habitat for Zarzian loach. Therefore, it is necessary to consider special management measures for this species, whose presence has been reported in this river recently.