نشریه بهره برداری و پرورش آبزیان
سال نهم شماره 4 (زمستان 1399)

In the present study, to evaluate the oxidation quality of fish meal stored at refrigerator temperature for 6 ‎months, a colorimetric nano-sensor aminated graphene oxide - bromophenol blue based on Whatman paper ‎was used. The results showed that the amount of moisture increased from 7.19% to 9.37% and ash content ‎increased from 7.29% to 8.04% during storage (P <0.05). The amount of changing in fat and protein contents ‎showed that fat content decreased from 12.87% to 10.53% and protein content decreased from 54.51% to ‎‎52.37% and showed decrease procedure during the storage period (P <0.05). Peroxide value (PV) increased ‎during the period, and the maximum amount of that was at the end of the storage period with 6.1 meq O2 / kg ‎lipid (P <0.05). The amount of thiobarbiotic acid (TBA) showed increased procedure and finally reach to 3.86 ‎‎(mg MAL / kg meal) (P <0.05). The color changes (ΔE) of the used nanosensor were increased during storage ‎period and changed from 29.04 to 52.67 (P <0.05), and also changed from green to blue and detectable by the ‎naked eye. Pearson correlation coefficients between PV and TBA indices with color changes index (ΔE) were ‎‎0.93 and 0.89, respectively. The results of this study suggest that the use of colorimetric nano-sensor aminated ‎graphene oxide - bromophenol blue based on Whatman paper with a simply color change process can be a ‎novel approach in determining the oxidation quality of fish feed during storage.‎

Fish sausage is one of the products that is produced to create variety and increase the consumption of fish. Since most of these products are made of fish, so they have a very short shelf life. One of the ways to maintain quality and increase the shelf life of such products is to use natural antioxidants. In this study, the essential oil of green pepper (Capsicum annuum) was extracted by water distillation (Clevenger). The amount of total phenol and DPPH in green pepper essential oil was 146.3 mg/g Gallic acid and 1.37 mg/ml, respectively. The extracted essential oil was sprayed on silver carp sausages at concentrations of 2 and 4% (W/V) and stored in a refrigerator. Then, at 5-day intervals, were performed chemical (pH, TBA, and TVB-N), microbial (mesophilic, Pseudomonas, coliforms and mold and, yeast), and sensory evaluation. Based on the results of the sensory, microbial, and chemical evaluation, treatment of 4% green pepper essential oil had the longest duration for 25 days and the difference between 4% treatment with 2% and control treatments was significant (p˂0.05). Therefore, the use of green pepper essential oil is suitable for preserving and extending the shelf life of silver carp sausage.

In order to survey the effect of Thyme (Thymus vulgaris) extract on the common carp , 180 fish with the average weight of 10.84±0.063 were randomly divided into four groups (with Thyme extract added in 0, 0.5, 1 and 2 % to the fish diet) in three replicates (each with 15 fish) for 70 days. At the end of this period, 30 fish from each group were exposed to the seawater with 13 and 14 ppt for 12 hours to survey biochemical parameters and survival rate and resistance, respectively. In this regard, blood samples were collected before salinity stress and 6, 24, 72 and 168 hours after salinity stress. Our results showed that added Thyme supplement into the food has no effect on fish resistance during the experimental period (P>0.05). Cortisol, glucose, total protein, albumin showed no significant differences between treatments before salinity stress (P> 0.05). However, increasing salinity increased cortisol and glucose significantly in all treatments compared to pre-salinity stress (P <0.05). Albumin and total protein did not show any significant difference in any treatments (P >0.05). Based on the results of the present study, adding thyme extract at 0.5, 1 and 2% into the diet did not have any effect on fish resistance and blood biochemical parameters of the common carp exposed to the salinity stress.

The aim of this study was to evaluate different filling media on some quality characteristics of canned rainbow trout. For this purpose, three groups of filler materials including salt water, tomato sauce and sesame oil were used to produce canned products. After three months of treatment at ambient temperature, the results showed that the highest amount of free fatty acids in the treatment of tomato sauce (0.93.0% of oleic acid) and the highest amount of thiobarbituric acid was recorded in the treatment of brine (0.131 ±0.003 mg malondialdehyde/kg) (p < 0.05). Results of trout meat fatty acids profiles revealed that there was no significant difference between the amount of docosahexaenoic acid (DHA), saturated fatty acids, and monounsaturated fatty acids between the treatments of tomato sauce and brine (p < 0.05). However, the highest total amount of polyunsaturated fatty acids (PUFA) was observed in sesame oil treatment (2.76 ± 2.63 g/100 g oil) (P <0.05). The highest level of PUFA in the filler medium was observed in the treatment of sesame oil (43.37 ±2.89 g/100 g oil) and the highest level of DHA was observed in tomato sauce treatment (2.39± 0.15 g/100 g oil). The colorimetric scores also showed that the highest L* levels were related to salt water treatment and the lowest values were related to tomato sauce treatment, and also the highest values of a* (18.32±0.72) and b* (35.90±0.42) were observed in tomato sauce treatment (p < 0.05). The highest results of sensory acceptance were recorded in the canned trout filled with tomato sauce compared to other treatments. According to the results of this study, tomato sauce is recommended as the best filling medium in canned rainbow trout.

This study was conducted to investigate the presence and passage of marine upstream fish in the up-water of Karun River in order to investigate the necessity of constructing a fish passage in the Mard dam structure. In Bahmanshir and Arvandrud Rivers the only and most important marine migratory fish that needs to migrate and presence at up-waters for reproduction and offspring survival is T. ilisha. River fish sampling was done using gill net and local fisher man. Among different reported fish, from physiological point of view, only T. ilisha needs to presence along the Bahmanshir, Arvandrud and Karun rivers from the estuary to upstream. Given the high impact of T. ilisha on livelihoods and the preservation of nutritional health of a large number of local and indigenous inhabitants of these rivers, the conservation of these fish stocks as well as the maintenance of river structures to support its reproductive migration from ecological, social and economic perspective of the region is very important. Thus, the authors consider the construction of a fish way as essential for the dam and shipping lock of the Mared structure. Based on the design prepared for the dam and Shipping Lock of the Mard structure, it appears that the dam structure itself have some parts that can be used as fish paths. Under normal conditions of water regime, during the year, side valves in the shipping lock with open water sea level could provide enough volume and velocity of water to stimulate swimming in T. ilisha as fishing path in Mared dam structure.

Determining morphological characteristics of exotic species is one of the important aspects to ecological studies that can be used in ecosystem management. In this research, some morphological characteristics of three-spined stickleback Gasterosteus aculeatus Linnaeus, 1758 in Gorgan-rud and Qarah-su River estuaries are surveyed. 147 specimens were collected using beach-seine with 0.5 cm mesh from February 2014 to April 2014. Samples were being biometry and age determination was done by otolith. Results showed that maximum age were 2+ and 3+ in male and female, respectively. The maximum length and weight were observed 7.62 cm and 7.43 gr and 6.93 cm and 4.43 gr in female genus in Gorgan-rud and Qarah-Su River estuaries, respectively. The growth model was positive allo-metric in female and male in Gorgan-Rud and Qarah-su Rivers. It was indicated body height and width, distance between initial dorsal fin and anal fin, eye diameter, distance between snout to end of dorsal fin and pectoral fin length showed more importance in distinguishing two populations from Gorgan-rud and Qarah-Su River estuaries. Also, it was observed macroscopic Corynoso mastrumasum in inner organs. It seems, the three-spined stickleback, exotic fish, may seriously dangerous for growth and survival of other fish species in the Caspian Sea basin due to the host of this parasite and transmission in the food cycle.

Alagol, Almagol and Ajigol wetlands of Golestan province have a cross-border chance to improve their position by being included in the list of Ramsar Convention. Climate change, water resources reduction and the pressure exerted by people groups of around the wetlands to exploit their biological and non-biological resources are among the challenges that need to be addressed and monitored as a result of protecting the triple wetlands by themselves. Today, with the implementation of alternative livelihood programs can improve rural economies and thereby reduce their need to use wetland resources. In the present study, after examining the five assets of social, economic, natural, human and physical in the two villages around the three wetlands (Tangli and Ookhi Tappeh) and using the rapid participation method, alternative jobs were set up and then with social evaluation, economic and environmental, the best options for training and expanding jobs to indigenous people have been proposed. The results of this study have shown that in these two villages, out of 13 proposed jobs, 10 environmentally friendly jobs can be planned and launched to support the triple wetlands. These jobs are based on excellence for training and implementation in these two villages, respectively, including Turkmen handicrafts, cultivation of rainfed and low-water-loving agricultural cultivars, vermicompost, ecotourism houses, production of medicinal plants, electricity farms, ostrich breeding and greenhouse products were suggested.