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Aims: Monitoring of the fish biomass is one of the basic principal of fisheries management, but ornamental and reef fish stocks, because of difficulty of estimating their abundance, have been less studied than others. The aim of this study was to estimate the standing biomass of ornamental and reef fishes in Larak Island, in the Strait of Hormuz.
Materials &Methods: Standing biomass of the fish species was assessed seasonally using Underwater Visual Census Method (UVCm) in coral reefs and  mesophotic coral reefs in Larak Island throughout 2018 and 2019. Two popular methods in UVCm (belt transect and stationary point) were used based on topography of sea bottom. The confidence interval of estimated standing biomass is calculated using bootstrapping method.
Findings: The standing biomass of ornamental and reef fishes is estimated as 2522.18, 5222.17 and 1325.15(Kg.) in Site 1, Site 2 and Site 3, that are located in 3-15meters depth. The standing biomass at Site 4, was estimated as 884.13kg. The minimum were observed in summer, also the result showed  that the standing biomass in summer was significantly lower than other seasons (P <0.05). In addition, the temporal diagnostic test showed that population structure of fish in the spring, autumn, and winter seasons was similar but significantly different from the population structure in summer.
Conclusion: The less of standing biomass in summer season can be affected  by seasonal migrations of fish in tropical and subtropical waters to deeper waters, in order to trade of the stresses caused by temperature fluctuations.
 

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Estimation of coral fishes biomass is needed as a basic benchmark for assessing the ecological status and fishing potential of coral reefs. Different methods are used to sampling the biomass of these communities, that direct observation is one of the preferred methods with respect to the non-destructive advantage. The purpose of investigation was to estimation standing biomass of coral fishes by Underwater Visual Census method (UVCm) in Abu-Musa Island seasonally from October 2019 to September 2020. also confidence interval was calculated of these estimations from the bootstrapping test (95%). Standing biomass of Coral fish and their confidence interval (95%) by bootstrapping simulation (n=479) were determinated 2923.6 kg., 4576.2 kg, and 1645.4 kg for the stations one, two and three respectively. The difference in the biomass standing of coral fish in three station could be related to the lack of differences in the amount of developed reefs, coral communities and significant differences in habitat availability.  Also, the standing biomass of coral fishes in the Abu-Musa Island are limited, that can be attributed to their low habitat, shortage of carrying capacity and the short life of the Persian Gulf basin, and stress that occurs in the ecosystem, especially bleaching events, that need more study in the future.

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The use of Artificial reefs(A.Rs) are one of the methods used to rehabilitation of fish stocks. This involves studying the grain size composition of bed sediments and  Total Dissolved Solids (TDS), which are crucial components in terms of their location. For this purpose, three stations with three repetitions were selected in the eastern and western of Jask City Bay and the study was conducted in the summer and winter seasons of 2023.In the study of total suspended solids, the minimum value with the mean and standard deviation was 25.9±0.46(mg/lit)at the fourth station in the Eastern basin during winter 2023. The maximum value with the mean and deviation was 36.39±0.62( mg/lit )at the third station in the western basin during summer 2023. The analysis of sediment grain size in the stations revealed that the lowest and highest amounts of sand and silt were found in the western basin at 76.4% (third station, summer 2023) and 88.5% (second station, winter2023) respectively. Firstly, the strength of the substrate (grain size) is the most essential factor in establishing structures, which contributes to ecological and biological success. Considering the optimal range of this component stations, suggested as the suitable areas for installation of A.Rs, one area(Western of  Jask City Bay) and two area(Eastern of  Jask City Bay), respectively.