Papers by Samia M El-Mahdy
Egyptian Journal of Aquatic Biology and Fisheries
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Egyptian Journal of Aquatic Biology and Fisheries, Jul 1, 2023
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Egyptian Journal of Aquatic Biology & Fisheries, 2023
The marine fisheries of Egypt serve as a valuable economic resource, providing a significant sour... more The marine fisheries of Egypt serve as a valuable economic resource, providing a significant source of sustenance and employment for its populace. However, the sustainability of marine fish stocks is beset by a multitude of challenges including the exacerbation of overfishing due to the augmenting fishing effort. In this study, the economic importance of fish production in Shalateen fishing ground was studied to evaluate its fishery status. The computer program CEDA (catch effort data analysis), where the catch and effort data of the Shalateen fisheries were analyzed using the surplus production models of Fox, Schaefer, and Pell-Tomlinson with three error assumptions of normal, log-normal and gamma. The maximum sustainable yield (MSY) of the catch of some important fishes was estimated in Shalateen to evaluate the present status of the fish stocks exploited in Shalateen waters.
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Egyptian Journal of Aquatic Biology and Fisheries
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Botanica Marina
Macroalgae play a vital role in marine ecosystems, but human effects are threatening the composit... more Macroalgae play a vital role in marine ecosystems, but human effects are threatening the composition and structure of algal communities. In the present investigation, the spatial and temporal variations of species composition, functional groups and percentage macroalgal cover were studied in relation to seasonal fluctuations of some physicochemical parameters, to determine the ecological status of macroalgae in coastal waters along the coast of the northwestern part of the Red Sea, from November 2020 to October 2021. Fifty-five species of macroalgae were collected and identified from the sites studied. Five functional groups of macroalgae were recognized. Among these were two turf-forming species, 34 species of upright fleshy algae, and three crustose algae. There was a large variation in the cover, as well as in the species richness and assemblage structure of the macroalgae in different sites and seasons. Seasonal changes, determined by environmental conditions, led to small chang...
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Asian Journal of Fisheries and Aquatic Research
The lakes’ fisheries play an important role in the Egyptian economy. Egyptian lakes face many cha... more The lakes’ fisheries play an important role in the Egyptian economy. Egyptian lakes face many challenges such as over-fishing, illegal and destructive fishing methods, human activities and pollution which affected the fish production from it. The lakes’ contribution to the Egyptian fish production decreased from about 50% in 80’s to the only 10% during 2017. Lake Nasser, as one of the largest artificial lakes in the world, plays a significant role in Egyptian fisheries. Its mean annual fish production is about 28,000 ton, this constituted 18% of the total fish harvested from Egyptian lakes. The catch and effort data over 15 years were collected from the lake and analyzed to assess its status and to summerize the main problems facing its development and management. Maximum Sustainable Yield of Nasser lake with special reference to the Nile tilapia, the main species in the lake, is estimated based on catch and effort data from 2003 to 2017. The computer software packages of ASPIC had ...
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Egyptian Journal of Aquatic Biology and Fisheries
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Iranian Journal of Ichthyology, 2021
An increased understanding of fisheries target species population dynamics is a key requirement f... more An increased understanding of fisheries target species population dynamics is a key requirement for successful management. Age, growth, and mortality of Indian mackerel, Rastrelliger kanagurta were estimated based on samples collected from commercial purse seine fishery in the Egyptian Red Sea between October 2019 and September 2020. The age estimates were based on two readers to increase the accuracy of results. The age estimates, in the period of study, were observed at a maximum age for both sexes at 4 years old and the most sampled occurrences in the second years (2 years old). The von Bertalanffy growth function was estimated for males at L ∞= 343.83 -0.447 (t+0.474) ; for females at L ∞= 367.37 -0.357 (t+0.767) and combined at L ∞= 353.78 -0.406 (t+0.595) . The mortality rate was determined at 1.35, 1.32 and 1.37 year -1 and exploitation ratio at 0.417, 0.511 and 0.492 year -1 for males, females and combined receptively. The length at first maturity (L 50 ) was estimated at 2...
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International Journal of Ecotoxicology and Ecobiology, 2019
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Otolith morphology analysis is one of the main tools used for fish or fish stock identification. ... more Otolith morphology analysis is one of the main tools used for fish or fish stock identification. Moreover, otolith shape can also be used in fish dietary studies (stomach content) for the identification of prey fishes and their size according to the relationship between fish and otolith sizes. In the present study, the relationship between fish length and otolith morphological dimensions was investigated for the sabre squirrelfish, Sargocentron spiniferum (Forsskål, 1775) (family: Holocentridae). Samples of 185 fish were collected from the coast of the Red Sea, Egypt. To analyze the relationship between fish and otolith, otolith morphometric measurements (length, width, area, perimeter, weight, sulcus, and ostium) and shape factors (aspect ratio, compactness, form factor, rectangularity, roundness, ellipticity, squareness) describing outline shape were extracted using image analysis. Generalized linear models were applied for the relationship between body length and each otolith mor...
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Egyptian journal of aquatic biology and fisheries, 2017
Seabreams (Sparidae) are common coastal fish specie inhabiting tropical and temperate waters thro... more Seabreams (Sparidae) are common coastal fish specie inhabiting tropical and temperate waters throughout the world. Up to date, 117 of 15 genera have been ascribed to this family (Chiba et al., 2009; Iwatsuki and Heemstra, 2011 a,b). Seabreams represent one of the most important fish families in the Red Sea. Its ARTICLE INFO Article History: Received: April. 2017 Accepted: April. 2017 Available online: May 2017
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Egyptian Journal of Aquatic Biology and Fisheries, 2021
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Egyptian Journal of Aquatic Biology and Fisheries, 2021
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Egyptian Journal of Aquatic Biology and Fisheries, 2020
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International Journal of Science and Research (IJSR), 2016
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Egyptian Journal of Aquatic Biology and Fisheries, 2018
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Egyptian Journal of Aquatic Biology and Fisheries
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Otolith morphology analysis is one of the main tools used for fish or fish stock identification. ... more Otolith morphology analysis is one of the main tools used for fish or fish stock identification. Moreover, otolith shape can also be used in fish dietary studies (stomach content) for the identification of prey fishes and their size according to the relationship between fish and otolith sizes. In the present study, the relationship between fish length and otolith morphological dimensions was investigated for the sabre squirrelfish, Sargocentron spiniferum (Forsskål, 1775) (family: Holocentridae). Samples of 185 fish were collected from the coast of the Red Sea, Egypt. To analyze the relationship between fish and otolith, otolith morphometric measurements (length, width, area, perimeter, weight, sulcus, and ostium) and shape factors (aspect ratio, compactness, form factor, rectangularity, roundness, ellipticity, squareness) describing outline shape were extracted using image analysis. Generalized linear models were applied for the relationship between body length and each otolith mor...
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Acanthopagrus bifasciatus is a member of family Sparidae. It is a tropical coastal fish species d... more Acanthopagrus bifasciatus is a member of family Sparidae. It is a tropical coastal fish species distributed throughout the Red Sea and the western Indian Ocean. In the present study, 253 scales from ten specimens of A. bifasciatus (170350 mm Total length) were examined to elucidate their scale characteristics. A wide spectrum of intraspecific variation between different body regions of A. bifasciatus was recorded in terms of scale morphometric indices and primary and tertiary radii counts. The scale characters including rostral field, outer and inner lateral circuli, grooves, denticles, focus region, granulation in caudal field and lateral line canal were studied. Scale morphology and ultrastructure characteristics are important for fish identification, taxonomy and phylogeny.
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Egyptian Journal of Aquatic Biology & Fisheries, 2021
Population structure and differentiation of Parupeneus forsskali (Fourmanoir & Guézé, 1976) was s... more Population structure and differentiation of Parupeneus forsskali (Fourmanoir & Guézé, 1976) was studied by otolith shape variation using the ShapeR package. The quantitative shape analysis was used for studying otolith shapes. The outlines were analyzed with univariate and multivariate methods of Wavelet and Fourier transformations. There were significant differences (P<0.05, ANOVA) between geographically distant populations of P. forsskali collected from the Red Sea, Gulf of Suez and the Mediterranean Sea. The differences between populations were 85 % for the first discrimination. Additionally, the classification success with cross- validation for the three populations was 65%. The misclassification error for the linear discrimination analysis was 0.353. The observed morphological differences were supposed to reflect environmental effects or might be attributed to differences in lifehistory strategies. Studying Population structure and differentiation is important for designing appropriate regulations for effective fisheries management.
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Papers by Samia M El-Mahdy