Rabbitfishes, family Siganidae, are one of the most abundant fishes inhabiting the Red Sea and now widely distributed in the Mediterranean. Age and growth of Siganus rivulatus, the most common species, were studied from samples collected randomly between October 2017 and October 2018 from Shalatein landing site. Otoliths of 2000 specimens were used for age determination and the maximum attained age for this species was four years. The von Bertalanffy growth parameters L ∞ , K and t o and the instantaneous annual rates of total, natural and fishing mortality were estimated and consequently the exploitation rate was determined. It is found that the current exploitation level is higher than the optimum one reflecting the intensive exploitation of S. rivulatus in the Southern Red Sea, Egypt. Yield per recruit analysis revealed that fishing effort should be decreased. This can be adopted through closed seasons/areas, increase of mesh size, increase of minimum landing size and setting of a total allowable catch (TAC).
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 been used. The surplus production model of Schaefer was applied in this study. The obtained results proved the over exploitation situation for the lake fishery and to achieve the sustainability many applicable measures are recommended.
The fishery status of two carangid species; Carangoides bajad and Caranx melampygus from Shalateen fishing area, Red Sea, Egypt has been evaluated. Yield per recruit of the two species as a function of different values of fishing mortality coefficient, age at first capture and natural mortality coefficient was estimated. For C. bajad it is found that, the current fishing mortality coefficient (1.34 / y), age at first capture (0.35 y) and natural mortality coefficient (0.34 / y) give a yield of (304.8 g) per recruit. While for C. melampygus, the current fishing mortality coefficient (1.75 / y), age at first capture (0.35 y) and natural mortality coefficient (0.25 / y) give a yield of (675.63 g) per recruit. Yield per recruit for C. bajad and C. melampygus showed that, the maximum (Y/R) was obtained at F max = 0.5 and 0.8 for C. bajad and C. melampygus respectively. For management purposes, the fishing mortality which is related to the fishing effort of C. bajad and C. melampygus should be reduced by at least 50% as well as the length at first capture which is related to the mesh size should be raised to the length at first maturity to maintain this valuable fishery.
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