نشریه پژوهش های ماهی شناسی کاربردی
سال ششم شماره 1 (بهار 1397)

Association between environmental variables and target species is the most important point in aquatic ecology. This study considered the possible relationship of spatial, temporal and some satellite derived environmental variables on skipjack tuna (Katsuwonus pelamis) distribution to finally help implementing of ecosystem based fisheries management for stock recovery program and management of skipjack tuna. Results of generalized additive model (GAM) (by assuming two distributions; binomial and Gaussian) revealed temporal and spatial explanatory variables plus net primary production (NPP), sea surface temperature (SST), sea surface salinity (SSS), mixed layer depth (MLD) and ocean current indices have greatest impact on skipjack tuna distribution in both cold and warm season. Comparing of two different model showed, binomial distribution had higher ability in final model deviance explanation and its value in warm season was higher than cold season. In addition, habitat suitability study showed suitability of some parameters in cold and warm season were different, then it must be noticed in future studies. Since the first step in implementing ecosystem based fisheries management is the sufficient knowledge on ecosystem and distribution of target species in relationship to environmental variables, therefore this study could help Iranian purse seiners to improve their catch efficiency in order to help to implementing of ecosystem based management for skipjack tuna and future fisheries management in the Indian Ocean and Oman Sea.

In this study, the sagittal morphology of five species belong to the genus Epinephelus (Bloch, 1973) including; Epinephelus areolatus (Forsskal, 1775), orange spotted grouper E. bleekeri (Vaillant, 1877), typical grouper E. coioides (Hamilton, 1822), grouper five strips E. dicanthus (Valeniciennes, 1828), olive stains spotted Epinephelus stoliczkae (Day, 1875) from the Persian Gulf and Oman sea were studied. The results of comparative description and of calculating the three indices (E, R and S) showed that the studied species are different regarding some otolith features. The most differences are related to the rostrum, antirostrum, excisura regions as well as dorsal and ventral rimes. The sulcus is similar in almost all the species, and including a tubular ostia in anterior part, and a strongly curved cauada in the posterior part. However, E. stoliczkae is differing from the other species by having a deep excisura. As results, it can be concluded that like the most bony fishes, variation in rostrum and antirostrum can be used to discriminate species in grouper fishes.

In the present study, a 96 h LC50 of diazinon were firstly determined for Caspian roach (Rutilus rutilus caspicus) juveniles. In order to investigate sub-lethal effects of diazinon on biomarkers, the fish were exposed to its sub-lethal concentrations for 14 days. They were then exposed to water without diazinon for 10 days to evaluate the levels of thebiomarkers after recovery period. The amount of liver enzymes activity except lactate dehydrogenase significantly increased 14 days after exposure compared to control group (p<0.05). The increases in glutathione S-transferase and catalase depended on diazinon concentration, so that highest activity was observed in highest concentration (p<0.05). Liver enzymes activities were returned to their initial levels after 10 days of recovery period, so that, no significant difference was observed in enzymes activity, except superoxide dismutase, between exposed groups and control group (p>0.05). According to the results of this study it can be said that diazinon activate the antioxidant system in Caspian roach and after a recovery period antioxidant condition largely returned to its original state. Also it is suggested that oxidative biomarkers are appropriate indicator to show the health status of aquatic animals exposed to pesticides.

This experiment was conducted to study the effects of two types of prebiotics A, contain 16% beta-glucans and 80% mannan-oligosaccharides, and B contain 30% beta-glucans and 18% mannan-oligosaccharides on weight gain, feed conversion ratio, survival rate, carcass percentage, blood parameters, gene expression of transforming growth factor beta1 (TGF-ß1) at head kidney and intestinal morphology of rainbow trout. One thousand eight hundred of fry rainbow trout (mean initial body weight 6 g) were randomly assigned to nine polyethylene tank (300 lit) which contained 200 fish per each tank. Fish fed daily at 3.5% of mass body weight by one of three dietary treatments containing control (without prebiotic), and experimental diets A and B for 8 weeks. The amount of probiotic in both experimental diets was 0.96 g.kg-1 which get by addition of 1 and 2 g.kg-1probiotic A and B, respectively. At the end of experiment, results showed that growth performance of fish was not affected by prebiotics supplement but carcass percent and survival rate of fish significantly increased by feeding prebiotics (p<0.05). The albumin, total protein and globulin of fish serum were significantly increased by prebiotics supplement (p<0.05) and supplementation of prebiotic B showed higher effects. The prebiotics supplement significantly increased blood lymphocyte and the ratio of length to high of intestinal villus of fish (p<0.05). The gene expression of TGF ß of head kidney was significantly increased by dietary prebiotics supplement (p<0.05) and prebiotic A increased the rate of this gene expression. In conclusion, the results of this experiment showed that using of dietary prebiotics A improved immunity and carcass efficiency of rainbow trout and physiological response of fish are related to probiotic composition.

This study was conducted to investigate the toxicology effects of colloidal silver nanoparticles in the liver tissue of killifish Aphanius dispar during acute and chronic exposures. Acute toxicity test was conducted through 96 h exposure to concentrations of 0 (control), 5, 10, 20, 30, 40 and 50 mg/L and chronic toxicity test through 21 days exposure to concentrations of 0 (control), 0.25, 0.5, 1, 2 and 4 mg/L of silver nanoparticles. To evaluate the histopathological effects of colloidal silver nanoparticles in both exposures, fish liver tissue was examined. Fishes exposed to different concentrations of colloidal silver nanoparticles showed various degrees of tissue damages compared to the control treatment. In liver tissue, damages including hyperemia, hypertrophy, cells vacuolization, increased buildup of pigment cells and necrosis of liver cells were observed and as the concentrations of silver nanoparticles increased, these damages were also increased Since the silver nanoparticles cause damages to fish liver tissue, production and application of these nanomaterials and the release of wastewaters containing these particles to aquatic ecosystems must be under supervision and strict control.

Marine oil spill has negative effects on marine ecosystems. This study aimed to evaluate the effects of Iranian crude oil on some blood biochemical parameters of Asian sea bass (Lates calcarifer) fish. A total of 225 fish with an average weight of 7.22± 1.42 grams and an average length of 8.4 ± 3.47 cm in five treatments and three replications exposed to experimental treatments. Treatments included the control group, crude oil dispersed by chemical method, crude oil distributed mechanically, water-soluble part of oil, and a chemical dispersant as a positive control. Sampling was performed at 48 and 96 hours after exposure. Factors examined include alanineamino transferase (ALT), aspartate aminotransferase (AST), glucose, triglycerides and total protein in the blood plasma. There are not any significant differences in the activity of the ALT, glucose and total protein between all treatment (p >. 05). There are Significant difference between treatments of mechanically oil dispersant and chemically oil dispersant at the levels of the aspartate aminotransferase (AST) after 48 hours with other treatments) p <. 05). after 96 h exposure of treatments, mechanically oil dispersant, showed significant difference with other treatments (p <. 05). Significant affected in the activity blood plasma triglycerides after 48 and 96 h exposure between mechanically dispersed oil and water-soluble part of oil to control showed (p < .05). In general, the data shows that oil pollutants capable of disrupting in blood biochemical parameters such as aspartate aminotransferase and triglyceride levels, The results of this study showed that chemical and mechanically dispersion of oil can be induced a high concentration of oil in the water column, resulted in higher effects in blood biochemical parameters of Asian seabass juveniles at short-term exposure than other treatments.

The Caspian roach, Rutilus caspicus, is considered a new species for sustainable development and increasing the variety of cultured fish species in Iran. The aim of the present research was to study the effect of different levels of gammridae extracts on feed acceptability, utilization, growth performance and salinity stress resistance of Caspian roach. For this purpose, after evaluation of amino acids and fatty acids profiles, extract of gammaridae of Caspian sea shorelines was mixed with distilled water at two concentrations of (1:25 and 1:50) and sprayed on formulated feed by 2% before each feeding. Each concentration was tested in three replicates with a control. The experiment was carried out in 100-liter tanks which were filled by 80%. Twenty fingerlings of the Caspian roach weighted 4.3±0.5 g were introduced to each tank. Fish were fed to apparent satiation 3 times a day for 8 weeks. The speed of feed intake and effect of extract on feed acceptability were calculated in the first 15 minutes of feeding. At the end of the trial, growth parameters (final weight, weight gain, specific growth rate, condition factor, and feed conversion ratio) and resistance against salinity stress (15 mg/l or ppt) were measured. The results indicated that growth parameters significantly improved in fingerlings fed with diets containing gammaridae extract (P < 0.05), although no significant difference was found between two concentrations of extract (P> 0.05). In addition, the study findings showed that survival of fingerlings to salinity stress significantly increased after 72 hours (P< 0.05). The findings of the present study revealed that gammarus extract can increase feed acceptability and improve the growth in the Caspian roach due to its suitable amino acid and fatty acid profile.

This study aimed to investigate the effects of dietary amino-acid L-cysteine on the blood parameters of grey mullet (Mugil cephalus L.), exposed to heavy metals copper and zinc. The required juvenile grey mullets with an average weight of 27.4±3 g were captured from coastal waters of Chabahar Bay. The experimental fishes were exposed to heavy metals Cu and Zn and fed with three diets containing 25, 50 and 100 percentage of cysteine relative to the cysteine content of the basal diet for 45 days. Blood samples were taken from all treatments at three intervals of 4, 22 and 45 days after the onset of the experiment, and hematologic parameters including red blood cell count, hemoglobin and hematocrit and RBC indices of MCV, MCH, and MCHC were measured. Statistical analysis of data collected from the blood parameters showed that heavy metals Cu and Zn combined with different concentrations of cysteine had significant effects ​​(P<0.05) on the amount of red blood cells, hemoglobin, and hematocrit, MCHC, MCH and MCV.These factors had a significant increase in short term (4 days) compared to the control group, and showed a decreasing trend afterwards as the time progressed. The results of this investigation proved that the amnio acid systein does not affect the hematologic factors of grey mullet, and the observed variations in the studied factors were due to the exposure to heavy metals. Overall this research showed that the hematologic factors of this fish can be used as an appropriate biomarker in determination of heavy metals Cu and Zn in water resources.

The sturgeon eggs, upon fertilization and contact with water develop stickiness due to glycoprotein molecules in jelly coat layer. In artificial breeding, egg adhesion is a main problem. So, various techniques have been developed to address this problem. Many of methods being time consuming and may cause damages to the eggs. In this study, Sodium hypochlorite (SH) at 0.03% concentration for 40 s exposure time was tested on stellate sturgeon, Acipenser stellatus eggs and its effects was compared with other de-adhesion methods (Kaolin, tannic acid and clay). The lowest fungal and died eggs (31.94 ± 3.8%; P>0.05) and highest hatching rate (68.06 ± 5.5%; P>0.05) were observed at SH treatment. It was concluded that treatment with SH is a simple, inexpensive and rapid method for de-adhesion of sturgeon eggs.

Rutilus kutum is one of the most important economic bony fish species of Iranian costal of Caspian Sea. In present study, R. kutum fingerlings investigated in two different densities include of 26 and 40 fish/m3. Initial mean weight of fishes was 17.49 ± 1.004 g and the test organism housed in circular concrete pools of 3 m3 capacity with flowing water (0.15 L/second) and continusely aeration in 10 weeks. The result showed that final weight gain in treatment 1 and 2 was 38.1±1.43 and 34.1±1.39 g respectively. Also, growth indices include of weight gain performance, specific growth rate, condition factor and protein efficiency rate increased in high density treatment while food conversion ratio decreased, as their different was significance in two experimental treatments (p<0.05). The kutum reared in low density showed significantly higher survival rate (SVR) (with 88.8%) than high density (with 76.9%) (p<0.05). So, stocking density of 455 gr/m2 is more suitable for kutum rearing in concrete pond with Caspian Sea water.