Dhurmeea Z. auteur aut IRD Zudaire I. auteur aut IRD Chassot Emmanuel auteur aut IRD Cedras M. auteur aut IRD Nikolic N. auteur aut IRD Bourjea J. auteur aut IRD West W. auteur aut IRD Appadoo C. auteur aut IRD Bodin Nathalie auteur aut IRD text journalArticle eng text/pdf reformatted digital access The reproductive biology of albacore tuna, Thunnus alalunga, in the western Indian Ocean was examined through analysis of the sex ratio, spawning season, length-at-maturity (L50), spawning frequency and fecundity. From 2013 to 2015, a total of 923 female and 867 male albacore were sampled. A bias in sex ratio was found in favor of females with fork length (LF) < 100 cm. Using histological analyses and gonadosomatic index, spawning was found to occur between 10°S and 30°S, mainly to the east of Madagascar from October to January. Large females contributed more to reproduction through their longer spawning period compared to small individuals. The L50 (mean ± standard error) of female albacore was estimated at 85.3 ± 0.7 cm LF. Albacore spawn on average every 2.2 days within the spawning region and spawning months, from November to January. Batch fecundity ranged between 0.26 and 2.09 million oocytes and the relative batch fecundity (mean ± standard deviation) was estimated at 53.4 ± 23.2 oocytes g-1 of somatic-gutted weight. The study provides new information on the reproductive development and classification of albacore in the western Indian Ocean. The reproductive parameters will reduce uncertainty in current stock assessment models which will eventually assist the fishery to be sustainable for future generations. specialized OCEAN INDIEN 036 040 11 12 e0168605 [22 en ligne] 2016 1932-6203 https://www.documentation.ird.fr/hor/fdi:010067421 10.1371/journal.pone.0168605 1932-6203 [F B010067421] https://www.documentation.ird.fr/hor/fdi:010067421 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers17-01/010067421.pdf IRD - Base Horizon / Pleins textes 2017-01-16 2021-06-02 fdi:010067421 fre