نشریه پژوهش های ماهی شناسی کاربردی
سال هشتم شماره 4 (زمستان 1399)

Presence-absence and abundance of each fish species in a river habitat depends on several factors and they prefer a specific range of each habitat factor. The present study was carried out to investigate habitat suitability index of Capoeta capoeta and the effect of habitat factors on its distribution and abundance in Roodbabol branch of the River Babolrood (Mazandaran Province). To do, fish sampling was performed at 20 sampling stations during December 2017 and January 2018 and 11 habitat factors were measured at each sampling station. Then, habitat suitability curves for each parameter and suitability index of each station were obtained using HABSEL software. Also, determination of distribution pattern of C. capoeta and its relation with the best habitat factors were surveyed using dbRDA analysis according to its abundance at each station in Primer+Permanova (Ver. 6).Based on the HABSEL results, C. capoeta inhabiting in Roodbabol prefers wide locations with low water flow speed, temperature between 14 to 18°C, average depth (22 to 30 cm), average altitude (140-180 m), average EC (260-300 μS/cm), small grain size of substrate rocks (100-125 mm), high level of dissolved oxygen (12 to 13 mg/l), and average salinity (1.5-1.7 mg/l) which are covered by bush and shrubs and shadow level is 41-70%. Also, dbRDA graph based on DistLm model indicated that factors of depth and width in the first order and water flow with EC in the second order affected the abundances differences of C. capoeta among various stations.

Understanding the habitat requirements of native species is essential for sustainable exploitation, along with the conservation of biodiversity of riverine ecosystems that have undergone extensive changes in human activities. In this study, the Zarmood River, an important tributaries of Tajan River in the north of Iran was investigated to evaluate the habitat preference of Kura fish in different ages. For this purpose, a suitable site  was first selected and then  by electrofishing agrigate  at 110 points fishes were caught. At each point where fish were caught, environmental parameters such as depth, flow velocity, abiotic and biotic substrate type were also measured. Results have shown that fish of different ages have different preferences.

Study of fishes in aquatic ecosystems is important in many ways, including ecology, ethology, conservation and management of water resources, reserves and aquaculture, so the present study compared the geometric morphometrics of Barilius mesopotamicus populations in Iran. Some 460 specimens were sampled from Zardmashin, Aalaa, Jarrahi, Dez, Shur, Meymeh, Changooleh, Kangir, Doyrej, Ahram, Zohreh, Kheirabad, Karzin, Shahpur and Darolmizan rivers in Bushehr and Tigris basins. Some 17 meristics were counted under a stereomicroscope. The data were analyzed with multivariate statistical methods including PCA, DFA, CVA and cluster analysis. Multivariate comparisons showed no significant differences in the studied populations. Kruskal-Wallis analyses of the means of all meristic traits showed significant differences among different basins, although the PCA and CVA tests did not present these differences very well, thus generally, the studied populaions were overlapping.

Three-spined stickleback (Gasterosteus aculeatus) is one the main model species which can be easily cultured in laboratory condition. Since it is invasive species in the Caspian Sea and the origin of its entrance is not clear. Furthermore, the three-spined population in South of France in Delta of Rhone River (Camargue wetland) is distinctive from other European populations especially Mediterranean population, therefore, Genetic comparison of three-spined stickleback between Gorgan bay (Iranian Coasts) and Camargue Wetland (South France Coasts) was studied by COI sequencing in this study. For this reason, 10 individual fish were sampled from each studied region and kept in Ethanol 96% until the time of experimental performance. After DNA extraction and PCR Reaction by one pair of Cytochrome Oxidase 1 (COI), Results of sequencing showed that the amplified sequence has 680 bp. The low number of haplotype and low haplotype diversity in both studied region dedicated the low genetic diversity of those populations. Level of FST as a Genetic distinction was 0.333 which is indicated high Genetic distinction of both population. Inspite of low Genetic distance (0.002) between two groups based on Kimura 2 Parameters method (K2P), phylogeny tree showed that the fish population of Gorgan bay and Camargue wetland formed a distinctive sub-clade. Even it is hypothesized that these two population have mutual origin but due to low supportive degree (bootstrap) the relationship between clades was not solved and the origin of three-spined sticklebacks of Gorgan bay was not properly evaluated.

Gorgan Bay and the southeastern coasts of the Caspian Sea in the Golestan Province are important biological and fisheries areas., while in recent years, they have been heavily contaminated. In present study, the dynamic of fishes, using stable nitrogen and carbon isotopes was evaluated to determine the diet and its trophic status, which can accurately chart the ecosystemchr('39')s biological conditions. Accordingly, in September-October 2015 at 5 ecological stations, sampling of prephytones, macrophytes, macro invertebrates and fish, were taken and dominant species were subjected to isotope analyzes using the EA-IRMS device. The results of the nitrogen-15 and carbon-13 isotopes indicate an imbalance in ecosystem conditions that alters the diet of the organisms and reduces the efficiency of the food web. The main factors of pressure on the ecosystem, the closure of the main channels of the sea to the bay, the entry of various pollutants into the ecosystem and weak physiography of Gorgan Bay, were determined.

In the present study, time series data of catches of Ribbonfish (Trichiurus leuptrus), in the Persian Gulf and Oman Sea from 1973 to 2018 were used and the fishing trend and average relative increase rate of catches of this species for this period estimated. Using fishing trend (linear regression equation) and average relative increase rate in catches of Ribbonfish over 21-year period, the amount of harvest for the next 5 years (2019-2023) for the whole Persian Gulf and Sea of Oman and for each province, were predicted. Finally, the harvests of 32000 t, which ensure sustainable exploitation of Ribbonfish and sustainability of jobs created by this fishery in the Persian Gulf and Sea of Oman, proposed and recommended to Iranian fisheries authority for implementation.

Biodiversity conservation is one of the most important issues in todaychr('39')s world. Few studies to date on the biodiversity of the waters of the Persian Gulf and the Makran Sea indicate its remarkable species richness. This study aimed to investigate the morphometric differences of three fish species (I.edentulus, I.spilotus and I.pox) from Blenniidae and the populations of the studied species in the Makran Sea. A total of 67 specimens were captured during the spring and summer 1397 from the three stations of Tis, Lipar and Darya-bozorg by a hand net. 34 morphometric traits were measured using digital caliper. Three species and their populations were analyzed by SPSS software using univariate statistical methods (GLM) and Duncan. Multivariate analysis such as principal component analysis (PCA), and discriminant function analysis (DFA) and cluster analysis based on Euclidean distance were performed to investigate inter and intra-specific morphological differences in PAST statistical software. The results showed considerable similarities between I.spilotus and I.pox. Differentiation of three populations of I.spilotus species was mainly in the pectoral fin and the results showed significant differences (p<0.05) among the populations of this species. The body shape was considerably difference between the two populations of Lipar and Darya-bozorg of I.pox species. DFA analysis separated the later populations, as well. Although, the results of this study, based upon the traditional morphometric method was able to show the differences between the studied populations, Geometric Morphometrics and genetic studies could complement this research in the future.

Oxynemacheilus bergianus is found in several inland water basins of Iran. Due to its wide distribution, this study was conducted to investigate its morphological variation in basins of Caspian Sea and Namak Lake of Iran using geometric morphometric technique. For this purpose, a total of 115 specimens from five river (Sefid and Ghezel Ozan (Caspian Sea basin), Jajrood, Kordan, Qom (Namak Lake basin)) were caught and compared using geometric morphometric method. The results indicated a completely different body shape patterns in the studied populations. The results also showed a significant difference between the body shape of the studied and groups the most differences were related to tail length and depth, body depth, head length and position of the dorsal, anal and pectoral fins. The observed shape patterns can indicate habitat-dependent morphological separation and geographical distances that the geometric morphometric method was highly capable of separating morphological features due to their high capability.

The use of free amino acids in fish diets typically results in a change in dietary behavior and more feed intake. The purpose of the present study was to investigate the effects of different levels of amino acids L-Proline and L-Alanine on common carp. For this purpose, 450 number of juvenile common carp with an average weight of 14±0.2 g were randomly distributed in 30 tanks 300 liter equipped with aeration system. Fish for 60 day were fed with 10 treatments dietary includes three levels of proline (0.5, 1 and 1.5 %), three levels of alanine (0.5, 1 and 1.5 %), three levels of proline-alanine combination (0.5, 1 and 1.5 %) and basal diet (control). Blood samples were taken at the end of the period. At the end of the period, the treatments were exposed to 15 ppt salinity at the end of the period to evaluate the resistance of the fish to salinity stress. The highest amount of erythrocytes was observed in the combination treatment 0.75 + 0.75 proline-alanine, but there was no significant difference with other combination treatments and 1.5% alanine treatment but with other treatments, especially the control treatment showed a significant difference. White blood cell count was the highest in the combination and control treatments, which was significantly different from the other treatments. Hemoglobin, hematocrit, lysozyme, immunoglobulin, total protein and liver enzymes (ALP, AST and ALT) were not significantly different among all treatments. MCH was highest in 1% proline treatment which had significant difference with combination treatment 0.75 + 0.75 + proline-alanine but did not show any significant difference with other treatments. MCV value in combination treatment 0.75 + 0.75 + proline-alanine was significantly different from other treatments. Also, MCHC values ​​were not significantly different among all treatments. The highest amount of lymphocytes was observed in the combination treatment 0.5 + 0.5 and 0.75 + 0.75 + proline-alanine which was significantly different from other treatments, especially control treatment. The highest amount of neutrophils was observed in 1% proline treatment and the lowest value was in combination treatments (without significant difference) which were significantly different from other treatments. There was also a significant difference in the amount of monocytes and eosinophil between treatments. The highest survival rates were 58.60 ± 1.46 and 53.84 ± 4.41 in combination treatment 0.75 + 0.75 and 0.5 + 0.5 proline-alanine, respectively. Finally, it can be said that there is a significant difference in some of the results, it seems that the two amino acids L-proline and L-alanine at the combined level of 0.5 + 0.5% can be effective in improving hematological and survival parameters in juvenile cyprinus carpio.

To investigate the effect of its various aspects and the effect on growth, nutrition, and biochemical composition of body, Asian Sea bass fish with an average initial weight of 33 ± 0.9 gr were experimented in three hundred-liter polyethylene circular tanks in three repetitions. Feeding was done twice a day for up to 60 days. The results showed that growing Asian sea bass in fresh-water and seawater did not have a significant effect on growth performance indicators (except for the average final length) (P > 0.05). The mean secondary length in saltwater treatment was significantly higher (P < 0.05). Therefore, In addition, among the calculated nutritional parameters, only the food index received between treatments had a significant difference (P < 0.05) and other indicators and biochemical body compounds did not show a significant difference (P > 0.05). Cultivation of freshwater fish has a lower feed conversion ratio (0.92 ± 0.06); however, these changes were not significant. Overall, the study showed that it can withstand a wide range of different salinities for 60 days and grow well without showing any casualties.