نشریه پژوهش های ماهی شناسی کاربردی
سال یازدهم شماره 3 (پاییز 1402)

Given the importance of Pampus argenteus (Euphrasen, 1788), and the overfishing pressure, this study aimed to determine some population parameters of this species (mortality and growth parameter) in the Persian Gulf and Oman Sea. Sampling was carried out using trawl, gillnet, and Moshta during 12 months from April 2018 until March 2019. In this study, 955 biometric samples were weighed. An information-theoretic, multi-model inference (MMI) approach was taken to analyzing grow and best model was selected using Akaike’s information criteria (AIC). Chen & Watanabe Method was used to estimate the natural mortality. Mean length and weight values (mean ± standard error) for males were 16.68±0.22 cm and 202.71±7.75 gr, respectively and for females were 20.57±0.34 cm and 350.12±15.95 gr, respectively. Results showed that the Gompertz was the best model for male and female. The logistic model can be used to explain growth of males (considering to Akaike difference was less than two). The value of asymptotic length, k and L0 in Gompertz Model were estimated 29.53 cm, 0.527 year-1 and 4.1 cm for males, respectively and 36.2cm, 0.448 year-1 and 4.1 cm for females, respectively. Natural mortality, fishing mortality and total mortality and E was calculated 0.7, 0.81, 1.51 and 0.54, respectively. Results of this study shows that this specie is under overfishing pressure and need to better management policies in this area including time, place and fishing gear limitation for catching. Also overfishing can be reduced with building Marine Protected Area.

Estimation of initial production capacity is one of the important principles of water resources assessment and management. Due to the size, depth and different positions of wetlands (inlet area, middle and near the dam base) of some physicochemical parameters of water, plankton (phytoplankton and zooplankton), macrobenthos and fish from 3 stations, in Alagol wetland, 2 stations in Ajigol wetland and 2 stations in Almagol wetland were sampled for one year from winter 2016 to autumn 2017. Comparison of the three wetlands, the results showed that in all seasons, the highest biomass per hectare was observed that phytophagus fish and zoophagus fish in Ajigol is much higher than the other two wetlands. Regarding benthic fish biomass, most biomass was observed in spring, summer and winter in Almagol wetland and in autumn in Ajigol wetland. The highest abundance in all three wetlands is related to Gambusia and in excluding Gambusia fish, the highest abundance in Alagol wetland is related to crucian carp, in Ajigol capoeta and common carp and in Almagol, crucian carp and in relative weight, phytophaguus and crucian carp were the dominant fish. Also, catfish are found only in Alagol lagoon. It seems that the role of releasing benthic fish such as common carp should be considered more and invasive fish should be controlled.

The purpose of this study is to identify the Zooplankton and Macrobenthic communities and to determine the water quality using the Saproby and Hilsenhoff indices in the downstream of Tajan River with the aim of investigating the place of release fish fry. In this research, 7 stations were selected along the Tajan River from the downstream of Tajan Bridge to the mouth of the river and sampling was done monthly from May to October 2022. In Zooplankton sampling, 100 liters of water were filtered by a plankton cone net. Sampling of Macrobenthoz was done by Grab device (225 cm2) and Sorber sampler (1600 cm2) with 3 repetitions in each station. A total of 25 Zooplankton species were identified during one-year sampling in different stations from Holoplankton and Zoobenthoz groups. During this survey, 8 families including Chironomidae, Simuliidae, Baetidae, Hydropsychidae, Gammaridae, Lumbriculidae, Spionidae and Erpobdellidae were identified. The results showed that all the stations are on average in the β-mesosaprobity quality class with relatively polluted water. Based on Hilsenhoff biological index, the degree of organic pollution and water quality in different stations range from the high quality class (no pollution) in stations 6 and 7 (at a distance of 1 km from the coastline and the estuary) to the medium class with relatively significant pollution in station 1 and 2 (after Tajan Bridge and 15 km below Tajan Bridge). According to the results, it can be said that these indicators are suitable for evaluating the water quality of Tajan River and more suitable indicators should be used for stations 6 and 7. Station 4 at a distance of 7 km from the sea coast (Soteh) had the best water quality conditions with little pollution, thus it seems that the best place to release fish fry in terms of water quality conditions is in Soteh. Due to the proximity of the water quality distance in the study area, habitat parameters should be taken into account to determine the exact location of the release of fish fry.

Contaminants in aquatic ecosystems cause tissue damage in fish. In some cases, the effects of pesticide degradation on non-target organisms (aquatic) are greater than on target organisms (pests), which in turn causes faster and more aquatic deaths. The use of safety stimuli seems to be essential. The aim of this study was to investigate the effect of different prebiotic levels of Pleurotus ostreatus on histological characteristics of tilapia (Oreochromis niloticus) exposed to chlorpyrifos. This research was conducted in the fall of 2019. For this purpose, 120 tilapia fry were divided into 4 treatments for 42 days. Then, 0.5 ppm concentration of chlorpyrifos was added to each group for 16 days. At the end of the period, the fish were anesthetized with clove anesthetic solution (220 mg / l) and their liver tissue and gills were isolated for histological studies.  The results showed that the treatments exposed to 0.5 ppm chlorpyrifos (poisoned control without prebiotics) had the most destructive effect on liver and gill tissue. However, combined prebiotic treatments of Pleurotus ostreatus and chlorpyrifos improved tissue damage, indicating detoxification, and a concentration of 0.2 ppt Pleurotus ostreatus had the best performance against tissue damage to the liver and gills of tilapia, indicating improved resistance.

The effect of inclusion of Nanoselenium to the commercial diet on the growth indices, liver enzymes and immune system of juvenile Acipenser stellatus was investigated. Individual 120 juveniles with an average weight of 21.93±1.03 g were fed with diets A, B, C and D (containing 0.1, 0.2, 0.3 and no Nanoselenium) for 8 weeks. At the end of the rearing period, blood samples were prepared from fish to evaluate liver enzymes and immune system indices. The final weight and daily growth in fish fed with diet A (0.1 mg /kg) were significantly higher than those fed with diet C (0.3 mg/kg). But there was no significant difference with fish fed with diet D (non Nanoselenium). The condition factor and protein efficiency ratio of fish fed with diet containing 0.1 mg/kg Nanoselenium was significantly higher than fish fed with diets C and D. There was no significant difference in the of total immunoglobulin (IgM) and complement (ACH50) in different groups, But the secretion of lysozyme in fish fed with diet B was significantly higher than other groups. There was no significant difference in the activities of alkaline phosphatase, aspartate aminotransferase and alanine aminotransferase enzymes in fish fed with diets containing Nanoselenium compared to the treatment without Nanoselenium. It seems that inclusion of 0.1 and 0.2 mg of Nanoselenium per kilogram has a positive effect on the growth indices and immune system of Acipenser stellatus in growth stage.

The aim of this research was to investigate the effects of different postbiotic levels on growth indicators, feed consumption and antioxidant defense system in rainbow trout (Oncorhynchus mykiss). For this purpose, rainbow trout fry (2-3 grams) were fed with experimental diets containing different levels (zero (control), 2, 4 and 8 grams per kilogram) of postbiotics for 8 weeks. At the end of the period, the growth indices and serum antioxidant defense system values were measured. Growth indices (average weight, specific growth rate, food conversion ratio, survival rate) were not significantly different between fish fed with postbiotic based on Saccharomyces cerevisiae yeast compared to the control group, although the increase in growth compared to the group The witness was observed. The highest numerical value of growth was obtained in fry fed with 8 grams of postbiotic per kilogram. Also, improvement of food conversion ratio was observed in fry fed with postbiotics. Although statistically, this decrease in food conversion coefficient was not significant. In all antioxidant factors, a significant difference was observed between the control group and the 8 g/kg treatment group. A significant difference was observed in the amount of catalase enzyme between the control group and the treatment group of 2 grams and 8 grams per kilogram. Also, similar results were observed regarding the activity of the superoxide dismutase enzyme, so that a significant difference was observed between the control group and the 8 gram treatment group. Regarding the glutathione peroxidase enzyme, a significant difference was observed only between the control group and the 8g/kg treatment, and the highest amount of this enzyme was observed in the 8g/kg treatment. According to the results of the present study, it can be concluded that the use of postbiotics based on Saccharomyces cerevisiae yeast in the diet of rainbow trout can be recommended to improve the growth indicators and also increase the capacity of the antioxidant defense system in rainbow trout.