نشریه پژوهش های ماهی شناسی کاربردی
سال پنجم شماره 3 (پاییز 1396)

Feeding habits of bamboo shark (C. arabicum) were studied monthly in Persian Gulf (Bandar Abbas area) during the period from November 2015 to April 2016. A total sample of 180 specimens (including 102 males and 78 females) ranging from 37/2 to 73/4 mm total length, were caught in Persian Gulf waters (Bandar Abbas up to Qeshm island) using trawl and bottom gill nets. The contents of the stomachs consisted of mainly large quantities of fish (47%), crustaceans (31%), mixed materials (unidentifiable matter) (19%) and molluscs (3%). Based on the major food contents observed in different seasons, fish item was the most dominant in March (63 %) and the crustaceans items and Mollusca were the most dominant ones in January (45 %) and November (8%), respectively. There was no significant difference in terms of the diet composition in both sexes, but significant differences were observed in the preference for food items in different size groups. The Stomach emptiness index (CV) index varied significantly in both sexes that was ranged between 3/3- 23/3% and 3/8 - 11/8 % for male and female, respectively. Additionally the results showed that the maximum and minimum of Gastrosomatic index (GaSI) observed in March and April 2016, respectively.

Common carp (C. carpio) is remarkable commercially in the southern Caspian Sea, especially in the southeastern coast. Its biology in natural environments has been less studied despite the commercial importance and value of this species. In this study, a total of 328 specimens were sampled and analyzed during the sampling period. The minimum and maximum length for females and males were 63 mm and 99 mm, 656 mm and 563 mm, respectively. The species included 11 age groups on the basis of biometric data and the autopsy. Analysis of fish feeding strategies and percentage of empty digestive tract in different seasons was conducted using the Costello (1990) graphical method. Out of the 328 fish which were examined, 235 empty stomachs and 66 stomachs containing food were observed. The Stomach emptiness percentage was variable between 69.72 to 75 % in which the maximum and minimum was reported for winter and spring, respectively. Feeding indexes including: probability percentage (Fi), frequency percentage (Ai) and dominance index (Ip) were examined in the digestive tract during different seasons. In all seasons, the highest digestive content was related to molluscs. The annelids presented the second highest content in the fish stomach in spring and plants indicated the highest content in fall and winter. The most reason for changing in the priorities of the food items during the period of study is the abundance of available food sources. In fact, C. carpio is an opportunistic and flexible feeder based on abundance and accessibility of foods.

Population variations of southern king fish (A. mossulensis) from Tigris, Persis, Kor and Hormuz basins were investigated using morphological and molecular approaches. Measurement of 39 morphological characters in 110 specimens which were collected from 17 southern rivers showed that significant differences were observed in meristic characters among some populations. The results were in congruent with data from PhiPT index and K2P distance acquired from 1022 nucleotide of cytochrome b gene. According to the results obtained from 17 experimental populations, differences in meristic and molecular characters made Kor river basin population different from Hormuz and Persis sub-basins, while mentioned population was not different morphologically from Tigris sub-basin populations. Moreover, populations from Hormuz and Persis sub-basins were inseparable. Despite low gene flow observed in analysis of molecular variance between Kor basin population and most of other populations, there was no significant correlation between geographic and genetic distances. The morphological and genetic variations revealed among populations of this species might be caused by complex geological history of the region and relative or complete separation of basins from each other. Therefore, according to the data provided by this study, the divergence was evaluated at intra-specific variations.

To determine inter- and intra- population morphological variation of Caspian vimba (V. persa), a total of 135 specimens were caught by cast net and beach seine in southern Caspian from Gorganrud and Valiabad rivers and Larim and Mahmoudabad coastal waters. In the present study, 27 morphometric and 10 meristic characteristics were examined. Based on principal component analysis, linear combination of 27 morphometric and 10 meristic characteristics resulted in factors that showed certain specifications of relationships among characteristics. In morphometric characteristics, 6 factors with 79.26% and in meristic characteristics, 5 factors with 71.86% of phenotypic variation among individuals were chosen and Eigen values were greater than one. Discriminant functional analysis showed high similarity percentages among individuals in different regions. Cluster analysis revealed that Larim and Valiabad populations were separated from the rest of populations regarding morphometric and meristic characteristics, respectively. Significant difference was observed regarding most of morphometric characteristics among the populations, while this significant difference was observed only in a few meristic characteristics among the populations. Principal component analysis, discriminant functional analysis and cluster analysis showed that populations in four regions were not entirely separable. However, it is possible that they are from different populations due to different ecological conditions among study areas.

Kutum (R. kutum) is regarded as the most important commercial bony fish in the southern Caspian Sea. Restocking of this fish is done by releasing the larva produced by artificial propagation. In the present study, genetic diversity and structure of wild populations (caught in Gorgan bay and Gomishan wetland) and hatchery population used for restocking were investigated and compared using ten microsatellite loci. The microsatellite loci showed high polymorphism. The mean number of alleles was 9.4, 8.9 and 8 for Gomishan wetland, Gorgan bay and hatchery samples, respectively. The mean observed heterozygosity was 0.80 for Gomishan wetland samples, 0.798 for Gorgan bay samples and 0.728 for hatchery samples. Despite the lower levels of allelic diversity and heterozygosity of hatchery samples, no significant difference was observed in this respect. Twenty six cases out of 30 tests showed significant deviation from Hardy-Weinberg equilibrium. Moreover, high deficiency of heterozygosity was observed in some of loci. The mean values of Fst and Rst as the indices of genetic differentiation were obtained 0.018 and 0.044 respectively indicating low differentiation between the samples. The highest value of genetic distance was observed between Gorgan bay and hatchery samples. According to UPGMA dendrogram, the wild samples were separated from the hatchery ones. According to the obtained results, wild populations of Kutum had proper allelic and gene diversity in the investigated regions. However, considering the persistence of restocking programs by artificial reproduction, it is necessary to establish appropriate strategies to maintain and improve the observed diversity in wild populations.

Multispecies fishing is one of the traditional pots characteristics (Gargoor). The aim of this study was comparison of bait types (sardine, cuttlefish and catfish) and the bait shapes (pieces and minced), and their effects on catch composition, using eighty-four Gargoors (14 treatments and 6 replicates) in 2 stations located near-shore (4 miles) and off-shore (11 miles) of Gasheh beach (Lengeh Port) with soaking time of 24 hours. Results showed that the bait types had significant effect on frequency of Epinephelus coioides, Pinjalo pinjalo, Lutjanus johnii, Pomadasys Kaakan, Otolithes ruber and Argyrops spinifer. Epinephelus coioides had the highest frequency in both stations. The highest catch frequency was observed for cuttlefish and sardine baits and the lowest was observed for catfish bait. Regarding the comparison of biodiversity indices, Margalef index (D) revealed no significant difference among seasons in both stations. Evenness index (J) showed significant difference among seasons only in near-shore station, but for Shannon index (H’) significant difference was observed among seasons in both stations. Consequently, sardine in spring and cuttlefish in winter as bait had the best efficiency. In addition, because of low efficiency, using of catfish as bait is not recommended.

In a feeding trial, the effects of four levels of lipid (10, 15, 20 and 25%) and raw energy (including 18.8, 19.9, 21.4 and 22.5 kJ) with the same protein (45%) were evaluated to determine the appropriate level of lipid and dietary energy on growth performance and carcass composition of Siberian sturgeon (A. bearii). A total of 120 fish (15.6 ± 0.33 g) were randomly assigned to 12 fiberglass tanks of 500 liter (n=10 per tank) and fed manually 3 times per day for 12 weeks with ad libitum feeding. Results of growth trend at the end of the period showed that the fish fed with lipid content of 10 to 15 percent obtained significantly more weight gain (WG) and specific growth rate (SGR) than the fish fed with diet containing 20 and 25 percent of lipid. However the feed conversion ratio of fish fed with lipid content of 10 to 15 percent was significantly lower than other treatments. Analysis of fish carcasses indicated the significant differences in the composition of lipid, protein and ash. According to the results of present study, increasing of the lipid levels in diet of Siberian sturgeon (A. bearii) up to 15% can cause an improvement in growth rate, diet efficiency and carcass composition.

Cyanide-induced oxidative damage may be involved in tissue lesions caused by sub-lethal cyanide poisoning. In the present study, some biomarkers of oxidative status were evaluated in liver, kidney, gill, and brain of Common Carp affected by cyanide poisoning. Moreover, possible beneficial effects of Spirulina were investigated for improvement of oxidative status and prevention of further changes. A total of 90 fish (approximately 60g) were divided into three groups, with 30 fish in each group. Group 1 served as the control. Group 2 were exposed to 0.4 mg/L potassium cyanide and received the diet without Spirulina. Fish in group 3 were fed with Spirulina (10% in the diet) in KCN (0.4 mg/L) polluted water during 30 days. The findings of the present work showed that a significant increase was observed in malondialdehyde concentrations in liver, kidney and brain of common carp following cyanide exposure. In addition, cyanide poisoning caused increment of protein carbonyls in both liver and kidney, although this increase was only significant in kidney. Supplementation of Spiulina in group 3 showed that the levels of malondialdehyde in liver, kidney, and brain effectively decreased and also it caused decrease in renal protein carbonyls to the levels that were not significantly different from control group. The findings of the present study showed that Spirulina has ameliorating effect on the KCN-induced oxidative damage in tissues of carp. Based on the present results, it can be suggested that Spirulina might have preventive effects on cyanide poisoning in carp and its dietary supplementation may have beneficial effects especially for fish species inhabiting in polluted aquatic environments.

In the present study, a piece of the ovary of a 6 years old female Sterlet sturgeon (A. ruthenus), a farmed fish (729 g and 47.3 cm), was removed after anaesthetizing with clove carpel powder (0.4 g/lit). Ovarian follicles were isolated from each other and were washed using sterile phosphate-buffered saline (PBS) containing antibiotics. Follicular cells were then separated by treating oocytes with 0.25% Trypsin-EDTA in Ca2 and Mg2 free PBS and were cultured in medium L-15 supplemented with 20% FBS at 22°C (1.25×106cells/ml). After twelve days, when confluent monolayer cells covered the bottom surface of the flask, the cells were dislodged by Trypsin-EDTA solution (0.25%), and were then washed with PBS containing antibiotics and sub-cultured. In the experiments, ovarian follicular cell were cultured in L-15, DMEM/F12 and M199 media, 10%, 15% and 20% of FBS, and were incubated at 20°C, 22°C and 25°C. Cells in L-15 showed better growth but no cell growth observed in the other media. The cells could grow at temperature between 20°C and 22°C, and the results showed that the optimum temperature for cell growth was 22°C. In addition, the growth rate of follicular cells increased when the FBS proportion increased from 10% to 20%, with the optimal growth at the concentrations of 20% FBS. Most proliferation of cells obtained when the L-15 medium was supplemented with 20% FBS and the incubation temperature was 22°C. The most proliferation of cells obtained in L-15 medium with 20% FBS at 22°C.

Agricultural pesticides are important chemical pollutants which are extensively used worldwide. In this study, the effects of sub-lethal concentrations of Chlorpyrifos were investigated on haematological parameters of Grass Carp. In the present experiments, first the lethal concentration (LC50) of Chlorpyrifos was calculated, then the effects of different concentration of LC50 (10, 20 and 30 %) were studied on cortisol, glucose, RBC, hematocrit, hemoglobin, WBC and some other blood factors of Grass carp (C. idella) during 14 days. Blood sampling was performed at 12hr, 24hr, 96hr, 7d and 14d and blood factors were measured using standard methods. Result showed that with the increase in pesticide concentration, a significant increase was observed in the concentrations of glucose, cortisol, RBC, Ht, Hb, MCV, MCH and MCHC at 12hr and 24 hr, and then the mentioned parameters decreased at the end of the experiment period. In addition, WBC, lymphocyte and eosinophil significantly increased at high concentrations of pesticide, and monocyte and basophil decreased. According to the results, Chlorpyrifos have shown the intensive effects on physiological and immunological characteristics of the carp. Additionally, blood factors, especially the amount of RBC and WBC, can be introduced as health bio-indicator of Grass carp and aquatic environment.