فصلنامه شیلات
سال هفتاد و یکم شماره 4 (زمستان 1397)

In the present study, the effects of Lactobacillus rhamnosus oral administration on blood biochemical parameters of rainbow trout (Oncorhynchus mykiss) were evaluated under the stress induced by sub-lethal toxicity of malathion. A total of 180 fish with the mean weight of 43±2.6 g were divided into four experimental groups; control, oral administration of probiotic, exposed to malathion with oral administration of probiotic and exposed to malathion with probiotic free diet. Selected dose of malathion was 0.036 mg/L and the probiotic were also used at 1 g (1010 cfu/g) per kg of diet. At the end of the 28-day experiment period, the percentage of weight gain and some of the blood biochemical parameters of the fish were examined. The results showed a decrease in the percentage of weight gain in fish treated with malathion and oral administration of L. rhamnosus supplement did not have a significant effect on increase of this index (P<0.05). Providing probiotic diet to fish treated with malathion significantly increased the total protein and albumin levels compared to basal diet (P>0.05). Blood cortisol level in fish treated with malathion was higher than control group and oral administration of L. rhamnosus significantly decreased it compared to control diet (P<0.05). Plasma enzyme activity assay showed that using L. rhamnosus probiotic, except ALP of plasma did not have a significant effect on the activity of other enzymes in fish treated with malathion (P<0.05). According to the results, it can be concluded that oral administration of L. rhamnosus probiotic for rainbow trout at the time of exposure to sub-lethal toxicity of malathion does not have an effect on the reduction of tissue disorders and tissue damage but it can be useful in reducing stress and improving the immune system of the fish.

This study aimed to investigate effects of ecological conditions, physical and hydrological parameters of a river, and to examine the appropriate method to determine Alburnus mossulensis fish habitat desirability in the Dinvarab River in the Kermanshah province. Ecological factors including physical and hydrological variables of the habitat (water flow velocity, depth, river width, water temperature, the percentage of bedrock, average diameter of rocks, vegetation type of substrate, total soluble solids, electrical conductors and pH) were measured from the downstream to the upstream across the 1 km range and 854 specimens were caught from all stations. Habitat Suitability Index of each station was calculated using the software of R using four arithmetic average, geometric mean, minimum and maximum. The results showed that the average arithmetic model was the best method for calculating the habitat suitability index in this study. The station 2, with a habitat suitability index of 0.8 was the most desirable habitat for A. sellal. By calculating the optimal habitat area, it was found that 406.801 m2 of the River is suitable habitat for A. sellal. Assessment of the habitat conditions of this native fish can be useful in managing the Dinvarab River ecosystem to protect the habitat of the fish in environmental studies of water resources.

Persian Vimba (Vimba persa) is one of the most important fishes in Caspian Sea. This fish immigrates to rivers and wetlands during the reproductionseason. This study aimed to evaluate and compare the reproductive ability and histological properties of gonads in Persian Vimba immigrant to the Anzali Wetland and Sefid River. For this purpose, 114 fish were caught during reproductiveseason. Biometry, age determination, reproductive features and histological study of gonads were performed. The results showed that significant differences between different age groups in terms of weight, total length, gonad weight, gonad length and fecundity (P<0.05). There was no significant differences in terms of GSI, liver weight, HSI and relative fecundity (P>0.05). In addition, fish of the Anzali Wetland and Sefid River had a significant differences in terms of gonad weight, liver weight, HSI index, fecundity and relative fecundity (P<0.05) and no significant difference in terms of total length and fork length (P>0.05). Furthermore, there were stages of III, IV and V in the ovary development, and stages of III and IV in the testis development. Female Persian Vimba of Anzali Wetlandhad every three stages but female of the Sefid River had stages III and IV. Since the reproduction of fishes in Anzali Wetland is began and ended earlier than those of the Sefid River, it can be concluded that the reproductive time of Persian Vimba in Anzali Wetlandis occurred earlier than those of the Sefid River.

With the development of aquaculture during last years, there is increasing need to intensive culture methods and using recirculating water without losing its quality. Using ozone as a potent oxidant agent would lead to convert TAN and nitrite to nitrate and decrease in water turbidity. Among different methods of ozone injection, the method of serial injection has lower qualitative fluctuation and toxic impacts compared to others. The present study was conducted based on a factorial experimental design with a control (without ozone injection) and three ozonation levels (100-120, 250-300, and 450-500 mV) three times per day, each time 3 hours  after feeding with two levels of water exchange (2 and 6% of total water volume). Twenty fingerling of rainbow trout, O. mykiss, (17.2±2 g) were randomly distributed to experimental tanks. Measurement of the water quality parameters and biometry of fish were determined during study period. Serial injection of ozone was led to increase and decrease of nitrate and nitrite, respectively (P<0.05), both of them were less in 6% than 2% water make up. Although the highest ozone level reduced 17.6% TDS, but this change was not statistically significant (P>0.05), Also, ozone and its interaction with the water make up, did not have a significant effect on total ammonia and total phosphorus (P>0.05). On the other hand, water make up had significant effects on concentration of TDS (P<0.01), total ammonia and total phosphorus (P<0.05). While the effect of water make up and its interaction with ozone levels on nitrate and nitrite concentration was not significant (P>0.05). Ozone significantly affected on (FCR) decreasing, condition factor (CF) and specific growth rate (SGR) increasing (P<0.05); while water make up and its interactions with ozone levels did not have a significant effect on these issues (P>0.05). Based on the results, it can be said that using ozone in ORP level about 450-500 mV, improved water quality and ozonation along with an increase in make-up water level to 6% would lead to decrease in food conversion ratio and improve of condition factor and specific growth rate, and is a useful approach that can be used in super intensive and recirculated aquaculture systems.

In the present investigation, the quality of Kilka surimi (Clupeonella cultriventris) prepared by washing and pH shifting methods was studied during frozen storage (up to 3 months). During storage, the quality of surimi was evaluated by thiobarbitoric acid (TBA), total volatile compounds (TVB-N) and water holding capacity (WHC). The results showed that in the washing method, TBA index was higher than the pH shifting method (P<0.05). In terms of WHC index, although in both methods, this index was decreased during storage, however this decline wasoccurred more in the pH shifting method (P<0.05). TVB-N index in surimi provided by washing method were slightly higher than pH shifting method. The results showed that the quality indices in surimi produced by pH shifting method is better than those of washing method.

This study was carried out to find developing stages of Sterlet sturgeon (Acipenser ruthenus) during the daily sampling from hatching to 20 days post hatch (DPH). Samples were fixed in formaldehyde and measurements were carried out by a loop equipped with a micrometer. In this study, with increasing the age, all organs increased in sizes except in yolk sac volume which was decreased by increasing the age and absorbed in 10 DPH with mean total length (TL) of 19 mm. Melanin plug concentrated in last part of the digestive tract in 1 DPH larvae with mean TL of 8.2 mm, and in 4 DPH with 12.6 mm TL, started to excreted while in 7 DPH (16 mm TL) completely excreted with the opening of the anal. According to the results, for increasing the growth rate and resistance of larvae, it is recommended that to start the feeding of Sterlet sturgeon from 7 DPH.

The present study was performed in to investigate the changes in blood biochemical factors of Flower horn (Vieja synspilus) fed diets containing different levels of cow skin protein hydrolyze. For this purpose, a total of 216 fish were fed levels 20% (T1), 40% (T2), 60% (T3), 80% (T4) and 100% (T5) replacement of cow skin hydrolyze instead of fish meal for 100-days. Control diet (T6) have no cow skin hydrolyze. At the end of experiment, biochemical blood factors, including glucose, cholesterol, triglyceride, uric acid and total protein were measured. The results showed that glucose and triglyceride of treatment T2 with average of 41±0.88 mg/l and 152±0.69 mg/dl compared to control one with 40±1.87 mg/l and 149±1.81 mg/dl, respectively, were higher (P<0.05). The least amounts of glucose and triglyceride were observed in T5 with 38±2.65 mg/l and 143±1.72 mg/dl, respectively and in the case of triglyceride difference was significant with control treatment (P<0.05). The blood cholesterol in control treatment was 248±0.93 mg/dl higher than other treatments and the lowest level of cholesterol was measured in the treatment T5 (241±1.66 mg/dl) (P<0.05). The highest total protein and uric acid with 4.4±0.26 g/dl, and 0.11±0.04 mg/dl, respectively, were in T5 (P>0.05). The results represented the effecting the serum biochemical factors by type of diet.

Zooplankton is one of the major animal groups in aquatic freshwater ecosystems. Zooplankton community composition evaluation is a useful approach of water quality assessment. Therefore, the present study was aimed to investigate Behesht-Abad River zooplankton community (diversity and density) alterations at different seasons. The sampling operations were carried out from the autumn 1394 until the summer of 1395. The results were showed the presence of 3 orders of zooplankton including cladocera, copepoda and rotifera. Moreover, rotifera represented the predominant component but cladocera were the lowest. Summer population density was more than other seasons while the lowest zooplankton abundance were in winter season period. In addition, density of zooplankton was high at Koohrang and Behesht-Abad rivers crossing (station 6) while Bagh-Rostam spring (station 4) were lowest population density. Moreover, according to Shannon and Simpson biodiversity were elicited the highest biodiversity during summer and the lowest biodiversity during winter.

In this study, Sargassum angustifolium pigments were extracted by soaking method to identify process variables and optimize extraction conditions. In order to reduce the cost of extraction, RSM method and the optimal design with 3 independent variables and 5 replications at the central point (to calculate process repeatability) were completely randomized to determine the best combination of variables. Effective in the extraction process, chlorophyll a, total chlorophyll, total carotenoids and fucoxanthin were used. The results showed that the highest amount of fucoxanthin, total carotenoid and total chlorophyll was obtained in optimal conditions for 4 hours, 100% ethanol and 1:5 solid-liquid ratio. If the highest amount of chlorophyll a for 6 hours, 100% ethanol and a solid-liquid ratio of 1:10. The values ​​obtained in the experiment with the values ​​predicted by the software have logical relationships that indicate the appropriateness of the models used.

Iran is one of the main producers of Caviar. Culture of sturgeon is great economic and ecological importance for countries like Iran in the Northern provinces, including Guilan, Mazandaran and Golestan. This research aimed to identify and prioritize benefits and risks in this industry and its results could cover the risk management process by assisting managers. This study is applicable based on objective and data collection methods descriptive survey. For this purpose, we designed a questionnaire covering economic and ecologic aspects of the activity and distributed it to an expert team comprised economists, statisticians and aquaculturists. Data were analyzed using Excel and Expert choice software. With putting the benefits and risks in the most relevant category, a proposed hierarchy structure has been introduced for benefits and risks priority. Finally, because of the plurality nature of these indexes, AHP has been used for the rank benefits and risks in this study. The results showed that, benefits: maintaining sturgeon, favorable profitability and risks: Lack of experts, sturgeon diseases have the highest rank and also benefits: production of knowledge development, illegal fishing and risks: shortage of target market, insurance support have the lowest rank etc.