Variations Saisonnières Des Paramètres De Reproduction Et Relation Taille-Poids De Auxis thazard (Lacepède, 1800) Capturé Dans Le Golfe De Guinée Par La Flottille Artisanale Ivoirienne

Abstract

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 (

Breeding strategy of Nannothrissa stewarti Poll & Roberts 1976 (Clupeidae) in lake Mai-Ndombe, Democratic Republic of Congo

“…In any case, the energy allocation attributed to the constitution of genitalia appears to be less important for males than for females. These results are consistent with those obtained by Abekan et al (2017) on the study of Auxis thazard Lacepède, 1800 caught in the Gulf of Guinea by the Ivorian artisanal fleet. Two peaks are evident for the females, the first in April and the second in August.…”

Age, growth and maturity of frigate tuna (Auxis thazard Lacepède, 1800) in the Southeastern Brazilian coast

“…Our findings were also similar to previous observations in other locations, such as Indonesia, Sumatra and the Philippines (Noegroho et al, 2013;Tampubolon et al, 2016;Calicdan-Villarao et al, 2017). When samples were analyzed by month, the number of females and males was not significantly different, despite fluctuations over time, in contrast to observations in the Gulf of Guinea, where males were dominant all year-round (Abekan et al, 2017). Conversely, when samples were divided by size, females were most numerous, although only a few classes significantly diverged from the 1:1 ratio.…”

“…The peak of spawning activity for frigate tuna was restricted to spring-summer; however, fish in developing and spawning phases were observed almost year-round, as illustrated by the monthly evaluation of gonad development, and the presence of germinative cells in different developmental stages simultaneously. Like other tunas, A. thazard has an asynchronous oocyte development that leads to long and multiple spawning seasons throughout the year, as observations in India and Gulf of Guinea suggest (Rudomiotkina, 1984;Schaefer, 2001;Ghosh et al, 2012;Abekan et al, 2017). Collette and Nauen (1983) have also mentioned the occurrence of adult fish throughout the year in the eastern Pacific, although spawning activity increases during some months.…”

“…The positive allometric growth (b > 3) observed in our results suggests that frigate tuna in SE Brazil increases faster in weight rather than length. Likewise, frigate tuna in the Indian Ocean, Northeast Atlantic and Gulf of Guinea also exhibits positive allometric growth (Bahou et al, 2016;Tampubolon et al, 2016;Abekan et al, 2017;Herath et al, 2019, Darvish et al, 2020. For the North West Indian coast, Mudumala et al (2018) calculated b < 3 for A. thazard, indicating a negative allometric growth, which the authors suggested to be caused by the absence of juveniles in the samples.…”