نشریه بهره برداری و پرورش آبزیان
سال نهم شماره 3 (پاییز 1399)

The present study was conducted to extract antioxidant compounds from Azolla filiculoides using the ultrasound-assisted and Taguchi optimization methods. The results demonstrated that ultrasound sonication time has no significant effect on DPPH radical scavenging and total phenolic compounds (p> 0.05). The highest concentration of the extracted phenolic compounds was measured in the mixture of ethanol and water (p < 0.05) as well as in dried sample to solvent with the ratio of 1:15 (p < 0.05). The percentage of DPPH radical scavenging exhibited a wide range, with the highest level (75.5%) at 15 min (p> 0.05). Moreover, this index in the ethanol extract was considerably higher than that of in the other treatments (p < 0.05). Concerning Taguchi optimization method, mean comparison was performed after designing the experiments and revealed that the ethanol extract was chosen as the optimum treatment with the ratio of 1:10 of dried powder to solvent for 15 min. Taken together, A. filiculoides could be used as a cost-effective antioxidant source.

The fishery has direct and indirect effects on the aquatic resources and the entire ecosystem, and the structure and functioning of the food networks will change the ecosystems of the sea. The average (± standard deviation) of total catch during the 21 years of the study period was 70852 ± 131819 t with a 95% confidence level of 161,2122 t and 101515 t, with a significant increase in the trend (P 0.05 and R = 0.12). The increase in total fishing and the fishing in balance index, as well as the decrease of the trophic level index and the beginning of a reduction in the level of fishing for mollusks and cartilage fish in this province, can indicate the severe changes in the structure of aquatic species in this area. According to the above results, it can be said that in the current situation, the catch is out of optimal condition and it is recommended to reduce the exploitation or at least not increase exploitation.

In this study, the effect of adding Gracilaria persica powder on the fish sausage produced from common carp surimi in five experimental treatments including the control group (with no preservative agent), TN (with standard sodium nitrite weight ratio, 0.02% w/w), 3, 6, and 9% algae powder was evaluated. Various quality parameters of the produced sausage samples including total volatile nitrogen content (TVN), free fatty acids (FFA), cook loss, pH, expressible moisture content and water holding capacity were measured on 0, 7, 14, 21 and 28 days under the refrigerated conditions. At the end of the experiment, the highest content of TVB-N was in non-algae samples and the lowest value was in 9% algae (p < 0.05). The lowest amount of FFA was observed in the samples containing 6% and 9% algae powder (P <0.05). The highest value of cook loss was in the control group (65%) and the lowest value was obtained in 9% (50%). The highest percentage of expressible moisture content was observed in the control sample (25%) which had a significant difference with others (P <0.05) and the lowest value was in 9% algae powder (7.5%). The highest and lowest water holding capacity of the samples were measured in 9% algae powder and the control group, respectively. This study confirmed the possibility of producing the fish sausage without nitrite in order to ensure the consumer health and also maintain the product quality. The results of this study showed that the use of Grasillaria persica macroalga powder at the level of 9% showed the best results in the studied parameters.

The production of warm water fishes in the country accounts for half of the aquaculture products and is one of the most important factors in the development of this industry in the country. Nutrition and growth of these fish are directly and indirectly dependent on the primary production of the ponds. Phosphorus is one of the most important factors affecting primary production in warm water fish ponds but is also one of the major limiting factors of production due to the lack of access by primary producers to this critical element. Because of the type of management conditions governing these ponds, such as organic fertilization, feeding, entry of various organic matter through inlet water and lack of annual dredging, the organic load of sediments is very high and insoluble organic phosphorus forms a large part of total phosphorus in this ecosystems. Today, one of the most important approaches to increase the amount of water-soluble phosphorus using insoluble organic phosphorus sources in sediments is the use of phosphorus-releasing bacteria (PRB). These bacteria dissolve various insoluble organic phosphorus compounds in sediments by various mechanisms, such as secretion of enzymes. The purpose of this study is to introduce and investigate the challenges facing the selection and use of phosphorus-releasing bacteria affecting insoluble organic phosphorus compounds in sediments. Because choosing the right type of insoluble phosphorus source used in the isolation process of these bacteria can be an effective step to improve the performance of introduced bacteria (as biological fertilizers) for use in warm water fish ponds.

Regarding the valuable role of fish in health and its importance in household food basket, the present study aimed to investigate the status of fresh fish and fishery products consumption and to analyze the barriers to fish consumption among army personnel. The research was conducted among 306 army personnel through administering a questionnaire in Tehran, Mazandaran, Golestan and Khorasan Razavi provinces. Analysis of variance was conducted to identify significant differences across the three consumer groups (consumers with weekly, monthly, and yearly fish consumption) and demographic differences were also identified through analysis of variance and independent samples t-tests. Findings revealed that per capita consumption for fish, canned fish, and overall consumption was 4.3, 1.2, and 5.5 kg, respectively. Only 7.8% of households had fish in their weekly consumption. Findings also indicated that the more affordability of chicken compared to fish (particularly in household with less financial potential), having less purchase power among household (especially in northern household), the risk of using fish, dissatisfaction with fish quality (especially among less knowledgeable household with diploma degree), Lack of easy availability of fish (particularly in Mashhad and Shahriar), convenience orientation, difficulty preparing fish and being less expertised regarding selecting, preparing and cooking of fish (especially in non-coastal areas and among the youth) were among the main factors leading to decreasing fish consumption among Army households. The results of this study can in the educational and executive planning of the relevant national and military authorities to encourage households to consume fish and timely intervention to improve it be helpful.

The Persian Gulf hosts great biodiversity. With 400-450 species of fish, the Persian Gulf is a unique area in terms of biodiversity. Different systems of aquaculture based on the introduction of native or non-native species have a special place in aquaculture. Species diversity in aquaculture is an attempt to maximize the benefits of species diversity such as resistance to disease, rapid growth, economic production, etc. within the framework of the ecological conditions created in aquaculture. Among species of fish in the Persian Gulf, most species belong to coastal fish, which include 85 species (65.38%), followed by pelagic fish (17 species), flounders (13 species), demersal fish (5 Species), tuna (4 species), cod and fatty fish (3 species), and unidentified marine fish (3 species). In recent years, increasing attention has been paid to marine species in Iran, accompanied by a focus on the development of aquaculture in marine environments. The cobia (Rachycentron canadum) is a fast-growing species native to tropical and semi-tropical regions. This native species of the Persian Gulf and the Gulf of Oman is a rich source of Omega-3. Currently, a large number of fish species are being harvested in the Persian Gulf. Calculation of maximum sustainable harvest quotas for each species is one of the goals of fisheries management, requiring information on fish stock

In this experiment effects of singular or combined administration of formic acid and Pediococcus acidilactici on growth indices and resistance to salinity in common carp fingerling (Cyprinus carpio) were investigated. For this purpose 228 fish with average weight of 5.5±0.5 gr, were fed diets supplemented for 8 weeks using experimental diet including probiotic (0.1%), formic acid (0.3%), combination of probiotic and formic acid and a control group. At the end of feeding trial growth indices and resictance to salinity were evaluated. Significant differences (P≤0.05) were observed in final weight and weight gain in fish fed combined probiotic and formic acid compare with singular probiotic and control group. SGR and survival percentage showed no significant difference between treatments (P≥0.05). The least FCR were observed in fish fed combined probiotic and formic acid (p < 0.05). The results of this experiment showed suitable effect of using probiotic and formic acid espsially in combination form on growth and resistance to salinity in Common carp.

New sustainable aquaculture technology which is called biofloc technology (BFT) that consumed food waste, organic matter and compounds produced during the production by aquatic animals. Biofloc has two major roles: maintenance of water quality, by the uptake of nitrogen compounds and generating microbial protein which results in reducing feed conversion ratio and a decrease in feed costs. Biofloc is a rich natural source of protein and lipid available 24 hours per day for aquatic animals. The current problem in biofloc system is the difficulty in controlling and management of bacterial community composition for achieving optimal water quality and aquatic species health. More than 2000 bacterial species developed well in water containing biofloc., That most include photoautotrophic, chemoautotrophic and heterotrophic communities and heterotroph bacterium plays a key role in BFT. This review gives descriptive information about a bacterial community associated with biofloc, and its influences on aquatic species intestinal microbiota, which can further be applied to research on immunity, disease resistance and nutrition in aquaculture.

In this study, The effect some growth factors of Common carp (Cyprinus carpio) of feeding with different sources of zinc and iron (Nano-particles) was investigated. For this purpose, 420 specimens (with an initial average weight of 7.4 ± 45 g) were prepared. Fishes were sterilized and adapted to the laboratory conditions for 10 days. Then, fish were randomly divided into seven groups. The first group was considered as control and other groups received 10, 50 and 100 µg of iron and zinc nanoparticles per gram of diet for 75 days, respectively. The results of biometry showed that the fish fed with nanoparticles had better growth indicators than fish of control group. Also, improvement of growth indicators in fish fed with zinc was concentration-dependent, so that the greatest increase in growth factors was related to the zinc concentration (100 µg per g), but this finding was not observed in the fish fed with iron. The results showed that the adding of iron and zinc Nano-particles in the diet may play an important role in increasing and improving growth factors of Common carp.