Zudaire I., Chassot Emmanuel, Murua H., Dhurmeea Z., Cedras M., Bodin Nathalie. (2016). Sex-ratio, size at maturity, spawning period and fecundity of bigeye tuna (Thunnus obesus) in the western Indian Ocean.
Victoria Mahé : CTOI, 21 p. multigr. (Documents de Réunion ; IOTC-2016-WPTT18-37). Working Party on Tropical Tunas, 18., Victoria (SEY), 2016/11/05-10.
Titre du document
Sex-ratio, size at maturity, spawning period and fecundity of bigeye tuna (Thunnus obesus) in the western Indian Ocean
Année de publication
2016
Type de document
Colloque
Auteurs
Zudaire I., Chassot Emmanuel, Murua H., Dhurmeea Z., Cedras M., Bodin Nathalie
Source
Victoria Mahé : CTOI, 2016,
21 p. multigr. (Documents de Réunion ; IOTC-2016-WPTT18-37).
Colloque
Working Party on Tropical Tunas, 18., Victoria (SEY), 2016/11/05-10
Opportunistic sampling of bigeye tuna (Thunnus obesus; BET) was conducted in the western Indian Ocean from 2010 to 2015 to study important reproductive traits (i.e., sex-ratio, size at maturity,spawning season and fecundity) with the aim to provide reliable information to improve the stock assessment. Overall 507 BET were sampled (including 204 females, 216 males and 87 indeterminate fishes) from which 158 ovaries were analyzed histologically. Significant bias towards females was found in the sex ratio of small individuals while males appeared dominant at large sizes. High reproductive activity was observed from January to March. The size at which 50% of females reach maturity (L50) was estimated at 102±4.5 cm fork length (LF), setting maturity threshold at primary vitellogenic oocyte stage. Mean batch fecundity (FB) was estimated at 0.75±0.52 million oocytes and mean relative batch fecundity (FBrel) at 11.54±7.11 oocytes per gram of fish weight. No significant relationship between fecundity (FB and FBrel) and size (LF) was found.
