129 RESEARCH PAPER SUSTAINABLE AQUATIC RESEARCH www.saquares.com Sustainable Aquatic Research (2023) 2(2):129-144 DOI: 10.5281/zenodo.8302192 e-ISSN: 2822-4140 Spawning Season, Spawning and Nursing Grounds Identification of Asian Seabass, Lates calcarifer (Bloch, 1790) in the Bay of Bengal, Bangladesh Mohammed Ashraful Haque 1,2* , Md. Istiaque Hossain 2 , Shanur Jahedul Hasan 1 , Probin Kumar Dey 3 , Md. Ashekur Rahman 2 , Yahia Mahmud 1 1 Bangladesh Fisheries Research Institute, Mymensingh, Bangladesh 2 Department of Fisheries, University of Rajshahi, Rajshahi, Bangladesh 3 Department of Fisheries, University of Chittagong, Chittagong, Bangladesh. Citation Haque, M.A., Hossain M.I., Hasan, S.J., Dey, P.K., Rahman, M.A., Mahmud, Y. (2023). Spawning Season, Spawning and Nursing Grounds Identification of Asian Seabass, Lates calcarifer (Bloch, 1790) in the Bay of Bengal, Bangladesh. Sustainable Aquatic Research, 2(2), 129-144. ArticleHistory Received: 26 June 2023 Received in revised form: 19 August 2023 Accepted: 21 August 2023 Available online: 31 August 2023 Corresponding Author Mohammed Ashraful Haque E-mail:ashrafbfri@gmail.com, Tel: +880-1712-781357 Keywords Lates calcarifer Spawning ground Nursery ground Bay of Bengal Gonadosomatic Index Abstract The Asian seabass is a coastal perciform fish, faces limitations in natural recruitment due to a lack of suitable spawning and nursing habitats in the coastal waters of Bangladesh. This study aimed to uncover the spawning season, as well as spawning and nursery grounds, for seabass in the Bay of Bengal, Bangladesh. The research employed direct seabass collection, supported by the Gonadosomatic index and histological study, to identify the spawning phase. Findings revealed that seabass spawning aligns closely with the lunar cycle, with spontaneous spawning occurring during the new and full moon during the transitional monsoon period (April-June). Local fishermen have been harvesting seabass in the Moheskhali channel for over 50 years. A total of 762 running ripe males and females were captured from spawning grounds, exhibiting a male-to-female sex ratio of 4:1. Approximately 80% of females were observed in egg- releasing condition, with some partially spent and others initiating egg-laying post-capture without abdominal pressure. The peak spawning period was in May, with the entire spawning season spanning from April to June. Among 17 sampling sites, three were identified as seabass spawning grounds (Fadarchar, Bukkhilanirchar, and Barchar), while eight were identified as nursery grounds (SM para, Nuniarchara, Ghativanga, Chowfaldandi, Ramu, Gomatoli, Dulahazara, and Badarkhali). Seabass nursery periods extended from May to September, with the catch per unit effort of seabass larvae in nursery grounds ranging from 50-80 individuals/hour. The study underscores the need for habitat conservation and management to enhance reproductive and recruitment success, ultimately enhancing Asian seabass populations in Bangladesh.