مجله علمی شیلات ایران
سال سی و دوم شماره 6 (پیاپی 140، بهمن و اسفند 1402)

In this study, the effect of different levels of vitamin C on growth indices, hematology, and antioxidant enzymes activity was studied in Schizothorax zarudnyi. For this purpose, a total of 144 fish was randomly distributed in 12 fiberglass tanks (12 fish per tanks) and fed with 3 dietary treatments containing 100, 500 and 1000 mg/kg of vitamin C and a control group without vitamin C for 60 days. The biological parameters of juveniles were measured at the end of the experimental period. To measure liver enzymes, antioxidant enzymes and also blood parameters, blood sampling from the tail vein of fish were performed. The results of growth indices in different treatments did not show a significant difference with the control group (p<0.05). The highest mean final weight, weight gain and specific growth rate, condition factor, body weight gain percentage and lowest feed conversion ratio were observed in 1000 mg/kg vitamin C treatment. The amount of red blood cells in all treatments was significantly different from the control treatment (p<0.05). The highest amount of red blood cells was in the treatment of 1000 mg/kg of vitamin C, which was significantly different from the control group (p <0.05). Also, white blood cell count increased in all treatments and there was a significant difference with the control group (p<0.05). The highest amount of white blood cells was recorded in the treatment of 500 mg/kg of vitamin C. Which had a significant difference with the control group (p<0.05). The alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase had a significant difference with the control group (p<0.05). The antioxidant enzymes catalase, glutathione reductase, glutathione peroxidase, superoxide dismutase, total immunoglobulin, and total protein are significantly different from the control group (p<0.05). According to the analysis of the results, it can be acknowledged that vitamin C has a positive effect on blood factors and antioxidant enzymes in Schizothorax zarudnyi.

In the current work, a comprehensive assessment of the spatial distribution of heavy metals including Cd, Pb, Ni, Cu, Zn, and Cr was performed in the sediments of mangrove and coral areas from 32 stations located in Tiab, Azini, Lark,  Hengam and Qeshm, Island, Bandar e pol and Bandar Khamir during the 2021 to 2022. The concentration of heavy metals showed significant spatial variations between the areas. The highest concentration of Cd 1.64±0.01 μg/g was observed at the station "Near Tabl village, South of the mangrove trees". The station "Tiab, end of the estuary" had the highest concentration of Pb 17.87±2.17 μg/g. The highest concentration of Ni 135.22±1.85 µg/g was seen in "North Tiab station, irrigation branch". The maximum concentration of metal Cr 18.41±0.41 μg/g was observed at the "Center of mangrove reservoir" station. There was the highest concentration of Zn 94.61±30.74 μg/g in "Azini Station 2" and finally, the highest concentration of Cu 40.5±0.28 μg/g was observed in the station "Khamir port, sandy bed of mangrove trees". The stations located in Tiab and the mangrove reserve had a higher intensity of pollution than other places and showed considerable risks of pollution, especially in terms of Ni and Cd. Cadmium was considered as the most dangerous metal in the studied areas which is probably caused by industrial activities. It is necessary to consider comprehensive and impressive strategies to control and reduce these heavy metal pollutions, especially in Tiab habitats and mangrove reserves where show high intensity of Cd and Ni contamination to identify, and manage the sources of these pollutions and minimize the impact of human activities on mangrove and coral ecosystems.

This study aimed to evaluate the effects of feeding with different types of live feeds on growth performance, survival rate, body composition, and fatty acids profile of great sturgeon (Huso huso) larvae during short-time weaning to dry feed. A total of 1200 great sturgeon larvae with a mean initial weight of 0.43±0.01g were distributed randomly into twelve 80-L circular fiberglass tanks (100 larvae per tank) with three replicates. Afterward, the fish were fed with frozen chironomid larvae (T1), frozen Artemia biomass (T2), and a combination of them (T3). The control group © received only a commercial dry feed (0.5 mm: protein 55.59%, lipid 21.12%, ash 11.76%, and moisture 7.96%) throughout the feeding trial. For weaning, the live feed was reduced by 15% every two days, and the dry feed ratio was also gradually increased. According to the results, the final weight (4.99±0.16g), weight gain (4.57±0.17g), body weight increase (1081.53±72.75%), and specific growth rate (11.75±0.29%/day) were significantly higher in T1 than in other groups (p<0.05). The survival rate (56.50±1.32%) significantly decreased in the control group © (p<0.05); however, no mortality was observed in the group fed chironomid larvae (p<0.05). The crude lipid (1.32±0.08%) and moisture (80.98±0.17%) levels of T1 were higher than other groups, and the crude protein content was significantly higher in T3 (11.26±0.39%) and C (11.44±0.44%) than T1 (9.23±0.39%) and T2 (9.67±0.28%) groups (p<0.05). There was a significant decrease in total n-3 LC-PUFA fatty acids (9.53±0.04%) in T3 than in T1 (11.02±071%) (p<0.05). The EPA/DHA ratio in T1 was significantly higher (0.45±0.03%) than other treatments (p<0.05). Consequently, the administration of frozen chironomid larvae is recommended during a 21-day adaptation period of great sturgeon larvae to the dry feed, due to the optimizing effects on growth indices, survival, and fatty acid contents.

The covid-19 disease caused millions of people in the world to face a food supply crisis. This research was planned and implemented to investigate the impact of the spread of this disease on the fisheries activities of Iran as one of the branches of food supply. The operation of collecting research data through (1) designing general and specific questionnaires, distributing them throughout the country and completing them by fisheries activists in the areas of shrimp farming, coldwater and warmwater, fishing communities, and seafood processing centers of different provinces, (2) gathering information, directives, and necessary data such as the production statistics of the Iranian Fisheries Organization, and (3) a review of the research and actions carried out in other countries. The average reliability of 1044 completed questionnaires was determined as 0.81 based on Cronbach's alpha. The results showed that during the outbreak of the disease, providing inputs and raw materials for growers and processing factories was more difficult (with an average of 65±3%) and more expensive (with an average of 56±5%). The domestic and international restrictions imposed during the quarantine period can be considered as one of the main factors for the difficulty in providing raw materials. In this context, 79% of these people believed that the transportation of raw materials was more difficult these days and affected the supply of the product. The decrease in demand and the increase in the cost of production increased the amount of storage of the manufactured product, which increased the risk and cost for the producers. 70% of the respondents have observed and announced the concern about disease transmission by fish and the decrease in demand among consumers. In the field of employment and economy, the increase in the cost price of the produced product was observed to a higher extent in aquaculture sectors and seafood processing factories. Instead, the fishing community reported the highest rate of job loss among the research target groups. 80% of the production sectors announced that their income decreased during the outbreak of the disease. Also, the results of this research showed the reduction of workers and employees of the production sectors in all groups during the outbreak of the disease. In general, about 78% of the audience announced that the fisheries activities of the country were affected by the negative effects of the coronavirus disease. According to these results and the short-term impact of this disease, among the strategies to deal with crises, the strategy of endurance for similar crises is proposed. To increase the resistance of the country's fisheries sectors in similar cases in the future, solutions and measurements have been proposed such as classifying fisheries activities as vulnerable businesses, developing assistance programs and emergency operational packages, implementing promotion and information measures, regional management in the provinces to meet the needs of the markets, extending, automatic renewal of farm exploitation licenses, the strengthening and development of cold storage plants and processing factories, the necessity of immediate support for local fishermen, and the expansion of online methods of selling aquatic products.

In this article, the total concentration of toxic heavy metals such as lead (Pb), cadmium (Cd), mercury (Hg), and arsenic (As), which are mandatory elements of the World Health Organization (WHO) and the Food and Agriculture Organization of the United Nations (FAO), were determined to measure the health of the edible tissue of the Caspian Sea Rutilus kutum. 90 samples of Rutilus kutum were collected in three northern provinces (Gilan, Mazandaran, and Golestan) during 2021-2022. The concentration of Pb, Cd, Hg, and As of Caspian Sea Rutilus kutum samples were prepared by standard method and acid digestion. All samples were analyzed using flame, graphite furnace, and cold steam of the atomic absorption spectroscopy instrument. The results showed that 90% of all data samples (90th percentile) concentration of toxic metals in Rutilus kutum tissue decreased in the order of Cd >As>Hg>Pb. The amounts of Cd, As, Pb, and Hg in Rutilus kutum tissue were observed at not detected-0.31, 0.001-0.15, 0.001-0.060, and 0.001-0.020 mg/kg wet body weight, respectively. Also, the statistical analysis showed that two types of correlations were found between the concentration of metals and the total length and weight of Rutilus kutum: for Cd with total length (r=-0.46) and with fish weight (r=-0.51), for As with total length (r=0.30) and with fish weight (r=0.27), It showed negative and positive, respectively, but mercury and lead metals did not show correlation with biometric parameters. Comparing the current results with international standards showed that the four toxic metals Cd and As, Pb, and Hg were lower than the FAO and WHO standards concentration. The findings showed that the health risk assessment parameters (EDI, HQ, and THQ) for all metals were much lower than the recommended values. This showed that the consumption of Caspian Rutilus kutum in the study area did not have any adverse effects on human health due to the contamination of toxic metals.

This research was carried out in order to determine the length and age composition, calculate growth and mortality parameters and calculate the biomass of golden gray mullet in the Iranian waters of the Caspian Sea during the year of 2022-2023. The biometric data were collected from beach seine fishing cooperatives in the Guilan, Mazandaran, and Golestan provinces. The mean (± SD) fork length and total weight were measured at 29.9±4.8 cm and 305.7±143.0 g, respectively. The age range was 2 to 11 years, and more than 74.4% of the age group were 3 to 4 years with the mean (± SD) fork length of 26.3±5.1 and 31.3±5.6 cm, respectively. In the relationship between fork length and total weight, the values of a and b were calculated as 0.018 and 2.836, respectively, with a correlation coefficient of 0.97. Growth parameters, including the von Bertalanffy growth equation constants (K, L∞, and t0), were determined as 0.14 (/year), 64.0 cm, and -1.02, respectively. Mortality parameters, encompassing total mortality (Z), natural mortality (M), and fishing mortality (F), were calculated as 0.95, 0.30, and 0.65, respectively. The biomass of golden gray mullet was determined 12155.5 tons. This research provides valuable information in the direction of sustainable management and protection of golden gray mullet stocks in the Iranian waters of the Caspian Sea.

Knowledge of the proximate composition of invertebrates such as sea cucumbers helps to improve our understanding of the nutritional importance of these organisms. In this study, the approximate composition (protein, fat, ash, and moisture) of two species of sea cucumbers, Holothuria leucospilota and Stichopus herrmanni, in Chabahar Bay during 4 seasons of 2022, was investigated based on standard methods. Sea cucumbers were transported to the laboratory after collection. Approximately 20 grams of muscle was used for each sample. Analysis (in triplicate) was performed to check the proximate compounds. The results showed that the percentage of protein than fat was higher in both cucumber species and the percentage of protein and fat in H. leucospilota species was higher than S. hermanni, so that the highest crude protein in the summer season was for H. leucospilota species (72±0.54). 7.7%) and the lowest value was recorded for S. hermanni in spring season (3.23±0.26%). The highest fat content was observed in the spring season (4.56±0.29%) in H. leucospilota species and the lowest in winter season (1.47±0.66%) in S. hermanni species. The percentage of moisture and ash was higher in S. hermanni species than H. leucospilota. The highest humidity percentage was for summer season (87.09±0.45%) in S. hermanni species and the lowest for winter season (81.63±0.48%) in H. leucospilota species. The highest amount of ash was in autumn (4.81±0.49%) for S. hermanni and the lowest for H. leucospilota in summer (1.23±0.28%). Compared to the other studied species, H. leucospilota species is nutritionally more suitable due to its high caloric value and sufficient crude protein content.

Rocky shores or artificial structures increase the diversity of sessile and mobile fauna. On the Southern shores of the Caspian Sea, these areas have been constructed artificially. The bivalve Mytilaster lineatus is one of the non-native species of the Caspian Sea, which widely distributed in the southern coasts. In this investigation, a certain level of the breakwater walls in in both regions of the Anzali port and the Caspian port were scraped and cleaned off all organisms. The population structure, growth, and abundance of M. lineatus were seasonally investigated in the sampling units. M. lineatus species was not present inside the port area of Anzali region, while it was established in the marina area of the Caspian port but its abundance was gradually decreased. A gradually increase in the abundance and biomass of the bivalves was observed in both marine parts of the mentioned regions. Five months after the beginning of survey, all length classes were observed in the population after five months and the height length of 13 mm present in the specimens. One year after the first sampling, the maximum length was 17.13 mm. The growth rate in summer-autumn was calculated at about 0.075 mm per day. After one year, the biomass was about 2 kg per square meter, which shows that this species is extremely invasive in the southern Caspian regions. The abundance of this species in areas far from the coast can provide the food resources for many species such as sturgeon fish and Kutum, which can be investigated by a pilot program with creating artificial habitats.

This study aimed to compare reproductive indices of broodstocks between and within (control and selected treatments) four different populations common carp of Hungarian-originated (TATA), North Iran, China-originated (RAN), and South Iran (Khuzestan). Control and selected treatments in each population comprised the average of the broodstock population and those chosen deliberately from 30% above the population mean (apart from shooter fish with excessive growth and out of the normal range), respectively, to calculate the genetic progress. Male and female reproductive indices were checked respectively by evaluating sperm quality (spermatocrit, sperm density per milliliter, percentage of motile sperm, and motility duration) and measuring working and relative fecundity, ovum and hydrated egg diameter, fertilization rate, hatching rate, the larval survival rate, and larval size after hatching. The results showed that, despite the high fecundity in the South Iran population, it has the lowest egg diameter and larval survival rate (p<0.05). Although the China-originated (control and selected treatments) population had the lowest sperm volume, sperm density per milliliter, and percentage of spermatocrit among different populations, the selected-treatment had the highest motile sperm percentage and the motility duration, which resulted in the most elevated fertilization rate belonging to it (p<0.05). The highest survival rate 24 hours post-hatching was observed in China-originated (control and selected) and North Iran-control, and the lowest in TATA (control and selected), North Iran-selected, and South Iran populations (p<0.05). China-originated control population gained the highest larval survival rate 72 hours after hatching. Although it did not differ significantly with the North Iran (control and selected) and TATA-control (p>0.05) populations, it has meaningful difference with the South Iran, TATA-selected, and China-originated-selected (p<0.05). The larval size in TATA-selected, North Iran-control, and South Iran is significantly smaller than other populations (p<0.05). There is no considerable difference in larval length size of the North Iran population between the control and the selected treatments, but it is significantly more in control than selected treatments in the China-originated and TATA populations. This finding illustrated that the selective breeding of broodstocks did not affect the reproductive indices within populations and the larval survival rate in F1. However, it improved the larval size. China-originated and North Iran populations performed satisfactorily in male and female reproductive indices, respectively, and it is worth bringing into mind hybridization between the two populations in future studies.

A comparison of fatty acid levels of rainbow trout reared in brackish water and freshwater in the southern region of the Caspian Sea was done using four types of commercial feed. The fish with equal density and biomass were reared for 90 days. The fish weight was 500 g at the first of rearing, and they reached more than 1700 g at the end of the breeding period. To determine the fatty acid profile, 5 samples from each farm were taken from the dorsal muscle of the edible tissue of fish at the end of the rearing period. The results showed that the rearing environment, in addition to affecting fish growth and feed efficiency, also affected the meat composition of the fatty acid profile of fish meat. The maximum weight gain of the fish in freshwater was 1025 g, and in brackish water was 1291 g with a food conversion ratio of 1.27-1.32 and 0.97-1, respectively (p<0.05). The feed efficiency rate was obtained in fresh water 1.07-1.97 and in brackish water 2.29-2.59 (p<0.05). The total saturated fatty acids of fish in freshwater (22.24±1.07%) was lower than in brackish water (25.69±0.22 %) (p<0.05). The total of monounsaturated fatty acid and polyunsaturated fatty acids differed in farms independent of diet and rearing environment (p<0.05). However, the amount of omega-6 fatty acid was optimal (17.52-31.26%), and omega-3 fatty acid (0.10-0.12%) was far less than similar studies outside Iran. As a result, a small amount of omega-3 unsaturated fatty acid was used in the composition of the primary ingredients of the feed. Generally, the growth process, feed efficiency, and meat of rainbow trout raised in brackish water in a sea cage environment has relatively better quality than fish raised in freshwater.