Studies on age, growth, and mortality rates for management of the redspot emperor, Lethrinus lentjan (Lacepède, 1802) in the Egyptian sector of Red Sea
Zaahkouk, S., Khalaf-Allah, H., Mehanna, S., El-Gammal, F., Makkey, A. (2017). Studies on age, growth, and mortality rates for management of the redspot emperor, Lethrinus lentjan (Lacepède, 1802) in the Egyptian sector of Red Sea. EKB Journal Management System, 21(1), 63-72. doi: 10.21608/ejabf.2017.2384
Samir A. Zaahkouk; Hassan M. Khalaf-Allah; Sahar F. Mehanna; Fahmy I. El-Gammal; Ahmed F. Makkey. "Studies on age, growth, and mortality rates for management of the redspot emperor, Lethrinus lentjan (Lacepède, 1802) in the Egyptian sector of Red Sea". EKB Journal Management System, 21, 1, 2017, 63-72. doi: 10.21608/ejabf.2017.2384
Zaahkouk, S., Khalaf-Allah, H., Mehanna, S., El-Gammal, F., Makkey, A. (2017). 'Studies on age, growth, and mortality rates for management of the redspot emperor, Lethrinus lentjan (Lacepède, 1802) in the Egyptian sector of Red Sea', EKB Journal Management System, 21(1), pp. 63-72. doi: 10.21608/ejabf.2017.2384
Zaahkouk, S., Khalaf-Allah, H., Mehanna, S., El-Gammal, F., Makkey, A. Studies on age, growth, and mortality rates for management of the redspot emperor, Lethrinus lentjan (Lacepède, 1802) in the Egyptian sector of Red Sea. EKB Journal Management System, 2017; 21(1): 63-72. doi: 10.21608/ejabf.2017.2384

Studies on age, growth, and mortality rates for management of the redspot emperor, Lethrinus lentjan (Lacepède, 1802) in the Egyptian sector of Red Sea

Egyptian Journal of Aquatic Biology and Fisheries
Article 6, Volume 21, Issue 1, April 2017, Page 63-72  XML PDF (573.27 K)
Document Type: Original Article
DOI: 10.21608/ejabf.2017.2384
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Authors
Samir A. Zaahkouk1; Hassan M. Khalaf-Allah1; Sahar F. Mehanna* 2; Fahmy I. El-Gammal2; Ahmed F. Makkey2
1Zoology Department, Faculty of Science, Al-Azhar University, Cairo, Egypt
2Fish Population Dynamics Lab, National Institute of Oceanography and Fisheries, Egypt.
Abstract
Age, growth and mortality are very important parameters for rational exploitation and management of the fish population.  Age, growth, mortality and exploitation rates were studied to assess the current status of the redspot emperor Lethrinus lentjan stock in the Egyptian sector of Red Sea. The study was based on a total of 943 specimens that collected during 2014 and 2015 with total length range of 11.5 to 50.7 cm. Results showed that, the maximum life span of L. lentjan in the Egyptian Red Sea was 6 years and age group one is the most frequent one forming up to 54% of the total catch. L. lentjan attains its highest growth in length at the end of the first year of life (24.45 cm) after which the annual increment in length decreases gradually with the further increase in age. The b-value of length-weight relationship was estimated at 3.03 indicating a tendency towards isometric growth. The composite coefficient "kc" and the relative condition factor "Kn" were fluctuated according to different fish length groups and months. The length at first capture was Lc = 20.11 cm with corresponding age Tc = 0.58 year. The total mortality of L. lentjan (Z= 1.52/yr), natural mortality (M = 0.35/yr) and fishing mortality (F = 1.17/yr) were lead to an exploitation ratio of E = 0.77.  The high values of both F and E are reflecting the high level of exploitation of this species in the Egyptian Red Sea waters.
Keywords
Lethrinus lentjan- Age- Growth- mortality rate- Red Sea- Egypt
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