In this study, the seasonal variation in sex ratio, macroscopic stages of sexual maturity, gonado-somatic ratio, hepatostatic ratio, condition factor, and size-weight relationship in Auxis thazard from Gulf of Guinea were studied from January to December 2016. Sex ratio observed was in favor of males (1: 0,78; X² observed = 20,16 ˃ theoretical X² = 3,84 ; p ˂ 0,05). The variation of maturity stages associated with GSI, HSI, and K during different seasons of the year showed that this specie spawns throughout the year. Length-weight relationship was W = 0,0039 L 3, 4108 (R 2 = 0,93 ; N = 291) for males, W = 0,0036 L 3, 4376 (R 2 = 0,91 ; N = 227) for females, and W = 0,004 L 3, 4118 (R 2 = 0,92 ; N = 519) for the combined sexes. The b value was significantly higher than the theoretical value of 3 for males (t-test, t = 233,218, p ˂ 0,05), for females (t-test, t = 227,776, p ˂ 0,05), and for all individuals (t-test, t = 315,821, p ˂ 0,05). This situation however indicates a faster increase of the fish in weight rather than in length. ResumeDans cette étude, la variation saisonnière de la sex-ratio, des stades macroscopiques de maturité sexuelle, du rapport gonado-somatique, du rapport hépato-somatique, du facteur de condition et la détermination de la relation taille-poids chez Auxis thazard provenant du golfe de Guinée ont été étudiées de janvier à décembre 2016. La sex-ratio déterminée a montré une prédominance des mâles (
The rainbow runner, Elagatis bipinnulata, which belongs to the Carangidae family, is regularly encountered in the landing of artisanal fishing in Abobo-Doumé (Republic of Côte d'Ivoire). The object of this work is to study the diet of Elagatis bipinnulata according to the marine seasons and the size of the various specimens (immature and mature). About 900 fish measuring between 43 and 93 cm (fork length -FL) were examined from September 2015 to August 2017. On the 900 examined stomachs, 541 were empty, which is giving a vacuity coefficient of 60.11%. A feeding index (IRI: index of relative importance of food item) combining three methods percentage occurrence, numerical method and weight method) was used. The identification of the items found in the stomach contents revealed that the principals food items were fish (%IRI=48.85) and crustaceans (%IRI=45.78). Cephalopods (%IRI=4.17), fish detritus (%IRI=1.2) and crustaceans (Portunus puber) (%IRI=0.55) are accidental food. The diet of the species does not change according to the seasons and the size of fish.
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