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The study of monitoring the environmental effects of fish cageculture on the southern shores of the Caspian Sea in the Nowshahr region was carried out from the autumn 2017 to summer 2018. Sampling of fish e was performed in four directions north, east, south and west around fish cageculturd. Sampling was performed during two periods, including the beginning of breeding activity and the middle of the breeding period. Fish were sampled using nets with mesh size of 24, 26, 28, 33, 40, 43, 44 and 55 mm. A total of 4 families and 9 species were identified, including Cyprinidae (whitefish and gypsy blackfish), pike family (Caspian pike and Caspian kilka), pike family (sand buffalo, deep-sea pike and Sirman buffalo) and salmon family ( Rainbow trout). Identified fish include Rutilus frisii, Alosa caspia, Neogobius fluviatilia, Clupeonella cultriventris, Ponticola bathybius, Ponticola syrman, Neogobius caspius, Vimba vimba and rainbow trout (Onchorhynchus mykiss). Overall, the frequency of fish caught around fish cageculture showed that the Clupeidae with 52% had the highest frequency and other families including Gobiidae with 33%, Cyprinidae with 14% and salmonidae with 1% in the ranks. They were next. Examination of the presence and absence of different species of fish around fish cageculture showed that 88.9% of fish were present in the western part of cages and in the eastern 66.7%, southern with 33.3% and north with 11.1%. Based on data analysis and one-way data test and Duncan test, in terms of average length, they were divided into two groups, with north and south directions in one group and west, east and south directions in the other group. The average fork length of fish had significant differences in different directions (p <0.05). In conclusion, From 16 different species of fish recorded in the annual catch of the Fisheries Organization of Iran that have economic and commercial value, 5 species were in around cagecultur with 31.5% which could be due to feeding habitat.
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