Population Parameters and Stock Assessment of Spangled Emperor Lethrinus nebulosus (Forsskål, 1775) in Jubail Marine Wildlife Sanctuary, Saudi Arabia MONA M. S. AL-QISHAWE, THAMER S. ALI* & ASMA A. ABAHUSSAIN Department of Natural Resources and Environment, College of Graduat Studies, Arabian Gulf University, Bahrain *Corresponding author: thamersa@agu.edu.bh Abstract: Stock of the spangeld emperor (Lethrinus nebulosus) sampled from commercial catches at Al-Freya landing site in the Jubail marine wildlife sanctuary, east of Saudi Arabia, was assessed from April 2012 to January 2013. Length-based stock assessment method using the FiSAT II software package showed that the von Bertalanffy growth (L∞Ȍ and K were 56.38 cm TL and 0.203 year -1, respectively. The annual growth rate showed that L. nebulosus attained the lengths 10, 18, 25, 31, 35, 39, 42 and 45 cm at the mean of the relative ages (0–XII), respectively. The total mortality, natural mortality and fishing mortality rates were 1.09 year -1, 0.45 and 0.64, respectively. The current exploitation rate (Ecurrent = 0.59) was beyond the optimum exploitation rate (Eopt = 0.522) and marginally lower than the maximum exploitation rate (Emax = 0.646). The length at first capture (Lc) was 22.24 cm, which is considerably smaller than the mean of maturation length (Lm) as reported in the Arabian Gulf (32.5 cm) as well as lower than the length at which yield per recruit could be maximized (39.5 cm). The results suggest that an increase in mesh size regulations for gillnets should be rapidly implemented to protect the stock of spangeld emperor in the east Saudi coast as immediate management action to be adopted by Jubail Fisheries Directorate. Keywords: Jubail, Saudi Arabia, Spangled Emperor, Stock assessment. INTRODUCTION Lethrinidae is a family commonly known as emperors, emperor breams, and pigface breams. These fishes are widely distributed in tropical waters of the Pacific and Indian Oceans across Red Sea, Arabian Gulf and East Africa to southern Japan and Samoa, with lesser extent in the eastern Atlantic. ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ ـــــــــــــــــــــــــــــــ Received: Sept. 25, 2016, accepted: Dec. 14, 2016 Biological and Applied Environmental Research, 2017 Volume 1, Number 1, 1-16