Papers by Mohamed G. Desouky
Fisheries and Aquaculture Journal, 2019
The evaluation and management of fisheries resources requires knowledge of spatial and temporal c... more The evaluation and management of fisheries resources requires knowledge of spatial and temporal changes in the habitat-associations of fishes as well as studying the biology and dynamics of commercial fishes of that fishery. The thin lip mullet, L. ramada is one of the most important and high valued species in Bardawil lagoon, Egypt. Long term commercial catch statistics show a significant decrease in the commercial landings of grey mullet in Bardawil lagoon since 1995. By learning more about this species and protecting the habitat upon which it depends, we can ensure that this important valuable fish remains abundant. Age was determined based on scale's readings of fish collected in May 2017 to December 2017 and in May 2018 to October 2018. Growth parameters, mortality rates, exploitation level as well as the critical lengths and ages were estimated. Based on yield per recruit analysis, the mullet fishery in Bardawil lagoon was found to be heavily exploited. The study suggested some applicable reference points for sustaining and optimizing the thin lip grey mullet yield in Bardawil lagoon.
Iranian Journal of Ichthyology, 2020
Population parameters of the Nile tilapia, Oreochromis niloticus were studied based on 1500 speci... more Population parameters of the Nile tilapia, Oreochromis niloticus were studied based on 1500 specimens (8-31cm TL) collected monthly from the Lake Manzala for one year. Age was determined based on scales’ readings and found to be five years. The length-weight relationship can be expressed as W=0.0143*L 3.08 . The von Bertalanffy growth equations were L t =34.51 [1-e -0.38(t+ 0.39) ] for growth in length and W t =776.12 (1-e -0.38(t+0.39) ] 3.08 for growth in weight. The estimated total, natural and fishing mortality rates were 2.02, 0.82 and 1.20 y -1 , respectively. The exploitation rate (E) was 0.59 and size at first capture (L c ) was estimated as 14.4cm TL. The relative yield per recruit reached maximum at an exploitation rate (E max ) of 0.6. Oreochromis niloticus stock may be unsustainable due to intensive fishing pressure to meet demand of growing populations, unless proper action is taken to manage the stocks.
Egyptian Journal of Aquatic Biology and Fisheries, 2015
Clariid catfishes are of great economic importance as protein food in adequate prices. For severa... more Clariid catfishes are of great economic importance as protein food in adequate prices. For several years, species of the genus Clarias (Scopoli, 1777) have been used in local fish culture, where they proved to be a fast growing protein source. Age, growth, mortality and relative yield per recruit of Clarias gariepinus in Lake Manzalah, Egypt, were investigated. The maximum life span based on otoliths' readings was 8 years, while the von Bertalanffy growth parameters were L∞= 86.88cm, K= 0.31/year and t 0 =-0.39 year. The mean annual instantaneous total, natural and fishing mortality coefficients were 0.98, 0.37 and 0.61/year, respectively. Accordingly, the exploitation ratio was 0.62, which was higher than the optimum one. Relative yield per recruit analysis revealed that C. gariepinus is over exploited in Lake Manzalah where the E 0.5 was lower than the current one (E 0.5 = 0.35). Some recommended management actions should be applied to strengthen the ban of fishing in the spawning season or in the nursery ground and to adopt a legal minimum size to protect the young and small-sized fish. In addition, to make any regulation more effective, all stakeholders (fishermen, scientists, non-governmental organizations and policy makers) should work together to establish a comanagement plan to conserve this valuable stock.
Fisheries and Aquaculture Journal, 2019
The evaluation and management of fisheries resources requires knowledge of spatial and temporal c... more The evaluation and management of fisheries resources requires knowledge of spatial and temporal changes in the habitat-associations of fishes as well as studying the biology and dynamics of commercial fishes of that fishery. The thin lip mullet, L. ramada is one of the most important and high valued species in Bardawil lagoon, Egypt. Long term commercial catch statistics show a significant decrease in the commercial landings of grey mullet in Bardawil lagoon since 1995. By learning more about this species and protecting the habitat upon which it depends, we can ensure that this important valuable fish remains abundant. Age was determined based on scale’s readings of fish collected in May 2017 to December 2017 and in May 2018 to October 2018. Growth parameters, mortality rates, exploitation level as well as the critical lengths and ages were estimated. Based on yield per recruit analysis, the mullet fishery in Bardawil lagoon was found to be heavily exploited. The study suggested some applicable reference points for sustaining and optimizing the thin lip grey mullet yield in Bardawil lagoon.
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Papers by Mohamed G. Desouky