نشریه علوم آبزی پروری پیشرفته
سال سوم شماره 1 (بهار 1398)

In order to improve the physical and mechanical properties,reduce permeability to water vapor, antimicrobial properties and increase hydrophobicity, Salvia officinalis essential oils was combined with the chitosan-tragacanth-clay film. The combination of nanocomposite with three levels of S. officinalis essential oil (1, 1.5 and 2%) in order to choose the best coverage for using in the maintenance of rainbow trout were studied. The best properties of film (Mechanical and antibacterial properties and water absorption)were showed in1.5 % S. officinalis essential oil in combination with nanocomposite. Samples coated with this bionanocomposite, showed the lowest amount of total bacterial loadand phsycrotrophic bacteria when compared to the control during 16 days storage period (p<0.05). According to the results, the combination of chitosan-tragacanth-clay withS.officinalisessential oil, can improve the physical and mechanical properties of chitosan in the film, moreover it can improve its ability to seafood preservation like trout.

Controlling reproduction in captivity is indispensable for aquaculture. In some fish, spawning conditions can be made by manipulating the light period and water temperature. But in many breeding fish, the progression in each stage of reproduction requires the administration of hormones from outside the body of the fish. In some fish, these hormonal manipulations are just as a management tool for increasing egg production and ease of work in the workshops. As for the rest of the fish, external hormones are the only way to produce eggs that will surely be fertilized. Hormonal manipulation of breeding fish is based on the use of the LH luteinizing hormone that acts directly on the gonadal surface, or on the synthetic agonists of the GnRHa gonadotrophin releasing hormone that acts on the surface of the pituitary to induce endogenous LH. Today, there are relatively few known hormones in finch fish, a relatively small amount of protein production. But those that have been cultivated have played a decisive role in aquaculture production systems, and their use in an appropriate framework and in a safe and sustainable way is not expected. In this paper, in addition to reviewing mechanisms for regulating reproduction in fish, important natural and artificial hormones used in aquaculture in the world and Iran, and their scientific and practical applications have been analyzed.

This study was carried out in 27 study stations in Shijan, Siahkishim, Abkenar, Hendekhaleh and Rogaha(River outlets), during conducting research hydrology  and  hydrobiology and preparing Atlas of  plankton in the Anzali wetland during the years 1994 from 2014. Sampling was done by (P.V.C) tube, For phytoplankton (1 liter of  water sampels) were Collected and fixed with 4% formalin and then transferred to the laboratory and after quantitative and qualitative studies with inverted microscope were taken picture them by Nikon photo microscop.  In total, 19 genus and 32 species were identified in the Cyanophyta. This phylum includes a category known as Myxophyceae, commonly called the "Blue Green Algae", The  most  abundant  species of Cyanophyta are Oscillatoria sp. ,Merismopedia  convoluta ,Microcystis  aeruginosa and  Anabaena spiroides. All members of this category have maximum frequency in the summer and early autumn seasons (October), and their most frequent distribution is in the Abkenar area. In general, the purpose of  this research  was  to  determine  the  role  and  importance  of  the environmental management of this group in Anzali wetland ecosystem. also, by studying  the  population, biomass  and  distrbution of  plankton  in  different areas  of  this  wetland, the production  and  fertility potential were evaluated  and  its environmental  effects in fish life have been met to restore the natural reproduction sites of migratory fish and feeding their larvae.

Identification and classification of cold water fishes in water resources of Iran is scientifically and economically very important. The study of geographical distribution, biological traits and ecological status of species groups in inland water resources and cultured systems are considered as base of programming for the conservation and sustainable exploitation of the genetic resources of these fish. According to the most reliable references, the most important indigenous cold water species in Iran with high economic value include several species of fish from Salmonidae (Salmo caspius and S. trutta), Cyprinidae (Squalius turcius) and percidae (Sander lucioperca). Problems such as genetic disorders and subsequent adverse and unfavorable their effects on rainbow trout, reduced stock of Caspian salmon (spring race), over-exploitation and illegal (Salmo trutta, Squalius turcius, Sander lucioperca), the lack of biological information from other species (Squalius turcius) have caused the genetic reserves of these species to be critically endangered, endangered and vulnerable.  Rainbow trout and Salmo caspius (because of their economic and nutritional importance) and Salmo trutta and Sander lucioperca are protected and exploited in the priority due to their vulnerability.

Territory of Digiche Environmental Assessment Plan for warm water culture in Geographic Coordinates ″ 49 ″ 55 ° 54 ″ 14 ′ 56 ° 54 East Longitude and ′ 7 ′15 ° 37 ″ 48 ′ 19 ° North Width Gonbad Kavous city (Golestan province) is located. The number of ponds exceeds 47 with a total area of over 380 ha with a net surface of about 324 ha, including carp farming. Implementation of the project will result in various changes and impacts on environmental resources (physical, biological, social, economic and cultural), so understanding how these effects are created will help to prevent or reduce these negative effects. The Leopold Matrix along with a checklist has been used to assess the environmental impacts of the Digiche area design. Using the above method, the effects of each of the construction and operation phases are predicted based on the matrix of activities and their effects. Based on the results, the construction phase (-46) has a negative score and the exploitation phase (+10) has a positive score on the physical environment and the construction phase (-29) has a negative score and the operational phase (+13) has a positive score on the biological environment also, the construction phase (+ 137) has a positive score and the operational phase (+ 327) has a positive score on the social, economic and cultural environment. Therefore, the implementation of modernization and optimization of other fishery systems has some adverse effects on the environment, but it seems that considering management strategies to mitigate the negative effects of the project on the environment, implementation of management plan and environmental monitoring and considering the positive impacts of the project on the area, the overall implementation of the project has positive and beneficial consequences for the local people, fishermen and fish farmers in the area. Also improved by implementing problems such as water scarcity due to loss of water in the canals, overall status of fish farming activity in the area, migration from rural areas to urban areas, lack of employment and consequently lower income and welfare of the people. There will be a positive trend. Therefore, implementation of the project is recommended and emphasized with regard to environmental measures.

Northern pike is the second most economically valuable fish species in Anzali lagoon which annually is caught 50 to 180 metric tonns in the area. The study of feeding regime of immature individuals of Esox lucius has been carried out in Anzali lagoon from April 2006 to March 2007. The main aims of the study were to determine the ecological role of the species in the area in order to manage its stock and elevate awareness level of fish culturists, too. Totally, 246 specimens of 0+ to 2+ years old with the total length 5.5 to 41.2 cm and weight 1.1 to 1438.0 g , respectively were studied. The results showed that the vacuity index was 17.9%. The mean length of gastrointestinal tract was 0.93±0.11 (mean±S.D) The mean fullness intensity index was 374.3±456.8 which showed a significant difference in different seasons, ages and stations (p <0.05). The study found that the young pikes in the Anzali lagoon fed 40 taxa of animals that fish had the most diversity, indicating euryphagous feeding behavior. Carassius gibelio, Proterorhinus nasalis, and freshwater prawn, Macrobrachium nipponense, were identified as secondaryfood items with 12.4%, 12.4% and 10.4%, respectively and these preys had the most relative importance in pikes growth, with 52.8%, 16.0% and 8.1% respectively. The present study showed that pike feeds especially more abundant, low-mobility and medium-sized preys, throughout the year, so that adequate prey should be provided for their breeding in order to decrease cannibalism risk.