مجله علمی شیلات ایران
سال سی و دوم شماره 1 (پیاپی 135، فروردین و اردیبهشت 1402)

This investigation was carried out to determine the effect of feeding strategies on growth performance, biochemical parameters, and hematological indices in male rainbow trout (Oncorhynchus mykiss) broodstocks. For this purpose, 45 broodstocks with 475.55 ± 54.24 g (mean ± S.D) were divided into three treatments and fed at satiation, restricted feeding (50% of satiation limit), and starvation levels in concrete ponds. The flow rate was 1 liter per second for each replicate and the broodstocks were fed for 8 weeks with extruded feed. According to the results, the final weight of the starvation treatment had a significant decrease compared to the restricted and satiated treatments (p<0.05). Moreover, the weight gain, body weight increase and specific growth rate showed significant differences among the treatments (p<0.05), but the condition factor was not significantly different (p>0.05). A significant difference was observed in feed conversion ratio between the restricted and satiated groups (p<0.05). Hematological indices did not show any significant difference between the treatments (p>0.05). In the blood biochemical parameters, plasma glucose level in the starvation treatment showed a significant difference with the restricted feeding and satiation treatments (p<0.05). In addition, blood globulin level of the starved fish was significantly different with the starvation treatment (p<0.05). In general, the present study showed that unpredictable stresses during the breeding season and the consequent reduction or interruption of feeding regimes could adversely affect the performance of male breeders, including growth indices and some physiological parameters.

The research study the effect of changing light color on the length and weight composition of common sprat (C. caspia) catch in conical lift net with a mesh size of 8 mm (knot to knot). For this purpose, in January 2018 the sprat fish caught by three fishing vessels during 30 times of fishing operations at 50-40 m depth in Amirabad fishing port. The results showed that from total number of 2874 caught, C. caspia with 79% was the most catch and C. engrauliformis and C. grimmi with 14% and 7% of the catch, respectively. Fish caught in blue light had a larger length range and more weight. While the fish caught in red light had the lowest length range and the lowest weight. In blue and red light, the highest and lowest average length and weight of C. caspia was 11.59 cm, 11.00 cm, 11.47 grams, and 11.00 grams, respectively. The length and weight of C. caspia caught in white light was intermediate.  The average length and weight of C. caspia caught using blue and red color, and white and red color had a significant difference (p<0.05).

The Caspian Sea is a unique brackish system in terms of water salinity, so evaluation of pollution criteria based on the water quality of the same sea is past and present. In this study, information was collected from 2008 to 2010 and analyzed during the project during these years, sampling of eight transects shorelines was performed seasonally at stations 10, 20, 50 and 100 m of depth in two summer and winter seasons for water and sediment. The results showed that the concentration of organochlorine toxins in the aquatic environment depends on its entry through the rivers leading to it and its concentration in water varies in different seasons and regions. The results showed that the concentration of organochlorine pesticides in the aquatic environment increased in winter of 2008 with the highest percentage of pesticides in spring, summer, autumn and winter in middle, middle, east and west and maximum percentages, respectively. Toxins were found in the water samples of the eastern part of the region by 75% in spring. Also the maximum concentration of organochlorine toxin belonged to α-Endosulfan toxin with a concentration of 3.86μg/l which was recorded in Nowshahr at 50 m depth of surface water. Conclusion In the current situation, the concentration of chlorine toxin compounds in the appropriate range and distance from the shore of water quality conditions is more suitable for fish farming in cages. Therefore, it is suggested to consider the establishment of fish cage culture at 50 m of depth.

The current research has been conducted to identify the impact of the spread of the Covid-19 pandemic on the breeding and propagation centers of coldwater fish, including the impact of inputs, production, and the supply process. The statistical population of this research was the propagation, rearing, and intermediate farms of coldwater fish in Tehran, Mazandaran, Fars, Kohgiluyeh and Boyer Ahmad, Kerman, Guilan, Zanjan, Chaharmahal and Bakhtiari, Isfahan, Lorestan, Markazi, and West Azerbaijan provinces. The number of farms investigated in this research was 75 farms. The results of this research showed that the outbreak of the Covid-19 disease had a strong impact on production activities in coldwater farms. For example, the fresh sales were decreased in 78% of the investigated farms. Restaurant demand for fish decreased in 82% of farms, and overall 90% of respondents reported a decrease in fish purchase demand in their sales markets. Also, the supply of inputs such as fish feed, eggs, and fry was faced with problems in more than 80% of the farms. The same problem was observed for selling products, where 93% of the respondents believed that the main reason was the restrictions on travelling during the lockdown. Finally, 93% of the respondents stated that the restrictions created during the outbreak of the disease had a negative impact on the production process, of which 67% declared that this impact was great. The results of the current research indicated the initial shock to the country's coldwater aquaculture industry in the early days of the outbreak of the Covid-19 disease. Results of present study are consistent with similar studies conducted in other countries. For this reason, using the strategy of endurance during the occurrence of similar crises through the compilation of government guidelines to support the aquaculture industry is known as the most appropriate strategy for the continuation and survival of the industry.

The impact of the covid-19 pandemic on job opportunities losing and life quality reduction of the traditional fisherman community of Iran in order to guide the interventions to maintain the employment and provide the livelihood of the fishing communities were studied in 2021 through an online electronic questionnaire. The data collection was done in a simple random way by sending the link of the questionnaire to the fishing community using the WhatsApp social network. The data quantification method was used to describe the results. A total of 693 questionnaires were received, of which 98.6% were men and 1.4% were women. On the other hand, 76.9% of the interviewees were young people under 50 years old. The results showed that 61.3% of the interviewees confirmed that at least one of their family members lost their job, 84.5% stated that their income decreased, and about 83.2% declared that they had lost their jobs for more than a month due to the spread of the Corona virus. Staying at home to avoid being exposed to the disease as the main reason for unemployment was declared by 65.3% of interviewers. Almost 32% of interviewees stated that they have the possibility of finding an alternative job, and among them, free labor jobs with 42.5% and agriculture with 25.8% were the most important alternative ways of generating income. The outbreak of the Covid-19 pandemic has negatively affected the livelihood of the Iranian fishing society, 89.3% of the fishing society was generally worried about preparing food during the Covid-19 pandemic period, and 59.6% were not able to provide their health and medical items. The results of this research recommend the intervention measures of the government regarding the livelihood of the fishing community during unemployment due to crises.

Nowadays, monitoring of heavy metals accumulation in aquatic tissue is one of the important research approaches to assessment of ecosystem health. This study investigated bioaccumulation of five heavy metals (cadmium, lead, zinc, chromium, and copper) in muscles of two fish species, Cyprinus carpio and Sander lucioperca in the Ilganeh Chai River. During 2020-2022, totally 52 samples (25 Zander and 27 Carp) were randomly taken where the Ilgineh River drains into the Ilgineh River Basin. The tissues of each fish were separated and digested in the lab and then analyzed using an atomic absorption spectrophotometer. Comparison of the mean concentrations of the heavy metals showed that the highest bioaccumulation levels in both fish species belonged to copper and the lowest to cadmium. These highest levels were lower than the maximum permissible levels set by the World Health Organization. The food-safety risk assessment of the heavy metals indicated that the estimated daily intake (EDI) value was lower than the tolerable daily intake (TDI) and risk assessment on non-carcinogenicity showed the highest levels of THQ were found for cadmium and the value of total non-carcinogenic (HI) for none of the elements was not higher than one . In addition, the highest value of cancer risk (CR) index belonged to cadmium (8×10-5), which was lower than the international standard permissible limit (1×10-4). Overall, the comparison of the bioaccumulation levels of the heavy metals in muscles of fish species examined with health index and international indicated that consumption of fishes are safe for human in this river.

The aim of this study was to evaluate the diet of the green tiger prawn, Penaeus semisulcatus for 12 months from January to December 2018 in the coastal waters of Hormozgan province. During this period, the intestinal contents of 673 of the two morphotypes of green tiger prawn including banding (417) and non-banding (256) were examined by the volumetric method. The results showed that the gut diet composition of both includes diatoms, dinoflagellates, crustaceans, mollusks, foraminifera, worms, and digestive material. There was no significant difference in the diet of the two types and males and females of green tiger prawns. Also, the study of the FP index showed that green tiger prawns were voracious creatures and their feed preference in female and male bonding was crustaceans 56% and 46% and 27% and 30% in diatoms, respectively, and in non-bonding types as well 65% and 57% in crustaceans and were 17% and 20% in diatoms respectively. Also, feed preferences in the next priorities for different sexes of both morphotypes included foraminifera, worms, unknown digestive substances, mollusks, and dinoflagellates with different percentages, respectively. There was a significant difference in the type of diet in different size classes so after crustaceans, diatoms were identified as the next preferred food in younger prawn diatoms and in older shrimp. The study of nutrition in different seasons of the year showed that crustaceans had the highest frequency and food preference in both morphotypes in all seasons and diatoms in summer, although the results related to the type and preference of food seasonally and based on the sex of shrimp showed no significant difference (P> 0.05).

The present research project has been implemented with the aim of introducing aquatic research axes based on the pillars of food security. For this purpose, the stakeholders, strengths and weaknesses, threats and opportunities of the sub-sector of fisheries and aquatics were investigated and the basic research axes were determined based on the elements of food availability, access to food, food consumption and health, and the stability and sustainability of food. Also, in addition to determining the research axes, the research priority of different groups and species of aquatic animals was determined based on the scoring index (0-10). The results showed that the beneficiaries of the fisheries sector have a wide range and the main ones who will directly benefit from the research results are aquaculture farmers, fishermen, processors and exporters of aquatic products. From the point of view of strengths, weaknesses and opportunities and threats, the existence of valuable genetic resources, fisheries knowledge and the country's policies for the development of fisheries and aquatics are among the strengths, and natural factors such as pollution of water resources, reduction of marine resources and climate change are among the most important threats. are counted From the point of view of the main axes of research in the pillar of food availability, fishing, stock assessment, aquaculture, health and aquatic diseases, in the pillar of access to food, supply markets, economic and social issues and the final price of the product, in the pillar of food consumption, quality and consumption culture, in the pillar of food sustainability, sustainable exploitation of aquatic life, reduction of waste, and increase in productivity were identified as priorities. In terms of species priority based on fertility, cold-water fish breeding, production management in shrimp, cold-water and warm-water fish, product health and transformation industries were given the highest points. In Caspian Sea aquatics, the most research points were given to health, nutritional value, storage, maintenance and market, and important Persian Gulf and Oman Sea aquatics received the most points for health and exploitation management.

Regarding the use of cypermethrin insecticide in agriculture in West Azerbaijan and the possibility of its entry into the Urmia Lake, the present study was conducted to investigate the effect of cypermethrin on growth, survival, and some physiological parameters of Artemia urmiana. For this purpose, the LC50 of cypermethrin for 24, 48, and 96 hours in the nauplii, post-larva, and adult stages were obtained using the probit test. The average LC50 of 96 hours was used to study the effect of chronic toxicity. Then, the Naplii was cultured in 4 treatments including the control group, 25% LC50, 50% LC50, and 100% LC50 for 15 days. At the end of the experiment, growth, survival, antioxidant enzymes activity, and digestive enzymes activity of the whole body were evaluated. The results showed that different concentrations of cypermethrin decreased the growth and survival of A. urmiana (p<0.05) and the amount of this decrease depended on the age of Artemia and the exposure duration. The highest decrease in growth and survival of different life stages of A. urmiana was observed in the 100% LC50 group. The results of antioxidant enzymes activity showed that cypermethrin decreased the levels of superoxide dismutase, catalase, and malondialdehyde (p<0.05), but there was no change in the activity of glutathione peroxidase (p>0.05). Also, the activities of lipase and alpha-amylase enzymes were decreased (p<0.05), but no significant difference was observed in the alkaline protease activity (p>0.05). In conclusion, the cypermethrin insecticide decreased the growth, survival, and antioxidant and digestive enzymes activities in A. urmiana.

This study was carried out to investigate some reproductive traits of Periophthalmus waltoni in the coast of Sirik city. Overall, 496 samples were collected during a year that 291 samples (58.67%) were male and 205 samples (41.33) were female. The sex ratio (M/F) was calculated as 1.41:1 (p<0.05). The smallest captured fish was male (4.8 cm) and the largest captured fish was female (15.5 cm). Based on the results, the average total length and body weight of males were significantly more than females (p<0.05). The male and female showed negative allometric growth. Also, b value of the male (2.65) was more than the female (2.63) (p>0.05). Absolut fecundity and relative fecundity were counted as 5216±2098 and 368±136 eggs, respectively. The results showed a direct relationship between the egg number and total length. According to the results, spawning period was recorded from January to May with two peaks in April and January, which was associated with a maximum mean of total length in this time. On the other hand, the results showed that there is an inverse relationship between temperature and gonadosomatic index.