نشریه پژوهش های ماهی شناسی کاربردی
سال سیزدهم شماره 1 (بهار 1404)

Clupeonella caspia fishing in the Caspian Sea has played a significant role in the regional fisheries economy over the past decades. However, a sharp decline in the stock of this species in recent years due to overfishing, environmental changes, and the introduction of invasive species has posed major challenges to the sustainable management of these stocks. This study employs the Stock Reduction Analysis (SRA) model to assess biomass changes and predict the allowable catch of the Clupeonella caspia in the southern waters of the Caspian Sea. This research utilizes historical catch and biometric data of kilka species over the past two decades and applies the SRA model to analyze stock trends and sustainable harvesting rates. Various management scenarios, including fishing effort control, harvest limitations, and setting catch quotas, have been examined. The findings indicate a declining trend in kilka stock, with improper exploitation threatening the biological and economic sustainability of the industry. A comparison of the results with previous studies reveals an increasing share of Clupeonella caspia in the catch composition and a decrease in anchovy Clupeonella caspia harvests. Furthermore, the simulation of management scenarios suggests that implementing catch restrictions and optimizing fishing effort can play a crucial role in the recovery of this species' stock. Based on the study’s findings, it is essential to develop and implement sustainable fisheries management policies, such as setting allowable catch limits and regulating fishing efforts. Utilizing stock prediction models can assist policymakers in making informed and sustainable decisions. This study recommends continuous monitoring of Clupeonella caspia stocks and periodic assessment of their biological status to maintain ecological balance and ensure the long-term economic sustainability of the fisheries sector.

This research aims to determine the physiological effects of the natural antioxidants of olive oil and the synthetic antioxidant of butyl hydroxytoluene (BHT) by studying the fatty acids of the diet and carcass and determining the food shelf life indicators (TVN and peroxide) in Persian sturgeon (Acipenser persicus) breeding was done. For this purpose, 315 juvenile fish with an initial weight of 108 ± 0.02 gr were selected and stored in seven treatments after acclimatization to the brackish water of the Caspian Sea. Three dietary treatments with concentrations of 1, 3, and 5% of olive oil and three other treatments with concentrations of 100, 150, and 200 mg/kg of diet from BHT and the control treatment without olive oil and BHT were fed to the fish, and each treatment with three repetitions for two months. The results showed that the fatty acids levels of diets containing olive oil and fish carcasses that used these diets had significant differences compared to diets containing BHT. The results of food shelf-life indicators showed that the shelf life of diets containing 1% and 3% olive oil increased. Based on the results, the amount of TVN decreased in all treatments compared to the control. However, the lowest increase in TVN was observed in treatments 1 and 2 (56.9 ± 0.38 and 59.8 ± 0.23 meq/100 g), respectively; which was significantly lower than the control and other treatments. The amount of peroxide in the control and treatments 3 and 6 was significantly higher than other treatments; But the lowest amount of peroxide was observed in treatments 4 and 1 (6.8 ± 0.17 and 7.23 ± 0.21 meq/1000 g), respectively, which was significantly less than the control and other treatments. In general, adding the natural antioxidant of olive oil 1 and 3% to the diet increased the shelf life of the diet and preserved the carcass quality of juvenile Persian sturgeon, and its addition to the diet is recommended.

This study compared the length frequency and average catch per unit effort (CPUE) of dolphinfish ( Coryphaena hippurus) caught using gill nets during two different fishing seasons (winter 1401 and spring 1402). Biometric data, including length and weight, were collected from 460 dolphinfish at four major fishing docks in Chabahar County. The length frequency of dolphinfish ranged from 69 to 111 cm. The average length in winter was 88.4 ± 4.9 cm and 86.7 ± 7.6 cm in spring. In winter, the highest frequency (19.3%) was observed in the 77-81 cm length class (45 fish), while the lowest frequency (0.4%) was in the 105-109 cm length class (1 fish). In spring, the highest frequency (19.2%) was in the 89-93 cm length class (44 fish), and the lowest frequency (0.4%) was in the 109-113 cm length class (1 fish). The minimum and maximum CPUE values in winter were 4.9 and 10.77 (kg/net panel/day), respectively, with an average of 8.4556 (kg/net panel/day). In spring, the minimum and maximum CPUE values were 6.15 and 9.9 (kg/net panel/day), respectively, with an average of 7.8083 (kg/net panel/day). While the length frequency of dolphinfish differed between winter and spring, no significant difference was found in the average CPUE between the two seasons.

The current study investigated some biological characteristics of wild-caught and pond-reared pikeperch (Sander lucioperca) from the Lake behind Aras Dam. The examined samples were 58 for wild fish and 33 for cultured fish. Total length, weight, age, gonad weight, condition factor, gonadosomatic index, hepatosomatic index, visceral index, and reproductive parameters in pikeperch were measured. The results showed that the mean total length (51.6 ± 5.4 cm), weight (1150.5 ± 442.1 g), and condition factor (0.8 ± 0.2) were higher in the pond-reared conditions compared to the wild group. The pikeperch examined in both wild and pond-reared conditions were in the age range of 2-4 years, with the 3-year-old age group having the highest percentage in both wild (53%) and pond-reared (71%) groups. The length-weight relationship in the wild conditions was determined as W= 0.0047x3.1269, R2= 0.7953, and in the pond-reared conditions as W= 0.0058x3.0794 with R2= 0.6877. Furthermore, the regression line slope or coefficient 'b' in both conditions was greater than 3, indicating a positive allometric growth pattern. Gonadosomatic, visceral, and hepatosomatic indices in both male and female pikeperch showed a significant difference between different ages (p < 0.05). The highest number of eggs/g in the wild was observed in the pond-reared conditions in the gonad weight range of 60-80 g, with 2183 eggs/g. The results also showed that the highest frequency of oocytes in the stage of III-IV (32%) was in the pond-reared conditions. Since the size and growth potential of pikeperch varies in different environmental conditions, the success of growth and reproduction of this fish in suitable conditions plays an important role in stock rehabilitation. The results revealed that wild pikeperch kept in pond-reared conditions have the potential for reproduction and fry production, making them suitable for this purpose.

The study of changes in absolute and relative fecundity and egg diameter based on the length, weight and age of tench, Tinca tinca in Anzali lagoon was carried out with the aim of developing the science and its application in the artificial propagation of this fish. For this purpose, 130 fish were caught from Anzali lagoon in May and June 2023, of which 89 were suitable for determining the fecundity. These fish had a body weight of 29.2 to 214 g, a total length of 13.5 to 22.5 cm, and an age of 4 to 7 years. The results showed that in the ovaries of adult fish, at least 3 categories or batches of large, medium and small eggs were observed, and the average number of eggs in batch 1 was 18479±6363, the total number of eggs in batch 1-2 was 29500±8507, and the annual absolute fecundity, i.e. the sum of the 3 batches of large, medium and small eggs, was estimated to be 43318 ± 14111. Also, the average annual absolute fecundity of eggs at the ages of 4, 5, 6 and 7 years was calculated as 28112±4828, 35660±7556, 46305±12408, and 60924±19171 eggs, respectively, and the average with the increase in the length and body weight of the fish increased. The average of the relative fecundity of the 1st batch, the total of the fecundity of the batches 1-2 and the annual relative fecundity (the total of the three batches of eggs) were calculated as 194±38, 315±67 and 464±124 eggs per gram of body weight, respectively. The average diameter of the eggs of batches 1, 2 and 3 was determined as 0.95±0.12, 0.63±0.09 and 0.35±0.08 mm respectively in the spawning season. The presence of 3 to 4 batches of eggs in the ovaries of females at the beginning of the spawning season shows that this species spawns several times in the breeding season in Anzali wetland.

Egg collection is a critical stage in rainbow trout (Oncorhynchus mykiss) propagation. Traditional manual stripping poses risks including altered ovarian fluid pH and physical injury to broodstock. This study optimized pneumatic extraction as an efficient alternative, evaluating the effects of gas type, flow rate, pressure, and needle specifications. Eighty 4-year-old female broodstock with a mean weight of 3783.5 ± 0.0035 g were allocated to experimental groups. Survival rate, stripping duration, ovarian fluid pH, fertilization rate, eyed egg stage, and hatching rate were measured. Pneumatic extraction at 1.5 L/min flow rate showed comparable survival to manual stripping (85-90%, p>0.05), while significantly increasing egg yield (497.1 ± 21.3 g vs. 345.0 ± 18.7 g, p<0.01). Gas type had no differential effect on reproductive indices (p>0.05). The method reduced stripping time by 32% (39.8 ± 5.2 s vs. 46.0 ± 6.1 s, p>0.05) and achieved complete abdominal evacuation. Findings establish pneumatic extraction as a standardized and operator-independent technique that enhances hatchery productivity while improving fish welfare by body surface manipulation and repeated anesthesia.

Heavy metals with their property of stability and indestructibility, accumulate over time in various tissues of aquatic organisms, including skin, bone, muscle, etc., and from this path enter the food chain and reach higher levels and consumption by other species are transferred. The present study was conducted to measure the amounts of heavy metals lead, nickel, zinc, iron and copper in the edible tissue of fish table islands (Qeshm, Hengam and Hormoz) in Hormozgan province. In the three mentioned regions, during the two seasons of summer and winter, a total of 180 samples were collected in 1398 (30 samples in each station and in each season separately). After bioassay, the concentration of heavy elements in the studied organ was measured using a flame atomic absorption device (Model 700Contr AA). The results showed that the highest mean concentrations of lead, nickel, zinc and copper were observed in Qeshm Island and iron metal in Hormoz Island and the lowest mean concentrations of metals were observed in Hengam Island. Metal concentrations in the analyzed samples were lower than international standards FAO, WHO, FDA, NHMRC and UKMAFF. Also, the level of potential risk and risk index for non-cancerous diseases in adults and children in the aquifer muscle tissue was less than 1. Therefore, it can be concluded that there are currently no problems for human health in terms of consumption of this fish.