Caractéristiques morphologique et histologique des gonades de Pseudotolithus elongatus (Bowdich, 1825) de la lagune Ebrié en Côte d’Ivoire

Pseudotolithus elongatus est un poisson régulièrement rencontré dans les débarquements de la pêche artisanale et commerciale pratiquée en lagune Ebrié. Cependant, en Côte d’Ivoire aucune étude n’a encore été menée sur cette espèce bien qu’elle ait une valeur commerciale élevée et qu’elle soit beaucoup prisée par la population. Du fait de l'intérêt commercial que présente P. elongatus, l'étude de sa reproduction est nécessaire si l'on souhaite assurer la pérennité de l’espèce et satisfaire le consommateur. L’étude de la morphologie et de l’histologie des gonades a été basée sur la taille, la forme, la coloration la présence ou l’absence d’ovocytes mûrs, le diamètre des ovocytes et l’observation histologique. Les résultats obtenus ont révélé six stades de maturation des gonades avec une gamétogenèse continue observée chez cette espèce. L’ensemble de ces informations contribueront à pérenniser l’espèce par une gestion rationnelle du stock.   English title: Morphological and histological characteristics of the gonads of pseudotolithus elongatus (Bowdich, 1825), from Ebrié lagoon, Côte d’Ivoire Pseudotolithus elongatus is a fish regularly met in the landings of the artisanal and commercial fishing on Ebrie lagoon. However, in Ivory Coast no study has been conducted on this species although it has a high commercial value and it is very appreciated by the people. Because of the commercial interest of P. elongatus studying its reproduction is necessary if one wishes to improve operations in order to ensure the sustainability of the species and satisfy the consumer. The studies of gonads morphology and histology of Pseudotolithus elongatus was based on the size, shape, staining of the gonads, the presence or absence of ripe oocytes, the diameter of the oocytes and the histological observation. The results obtained indicate six stages of gonad maturation with continuous gametogenesis observed in this species. All of this information will contribute to perpetuate this species through rational management of the stock. &nbsp

Biologie De La Reproduction Du Sciaenidae Pseudotolithus Elongatus Dans La Lagune Ebrie (Cote d’Ivoire)

The study of reproduction of Pseudotolithus elongatus in the Ebrie lagoon was investigated between July 2013 and June 2015 on a whole of individuals of 550 specimens. the total length ranges from 14.5 to 42.7 cm. The monthly evolution of the gonado-somatic index (GSI), the liver-somatic index (LSI), the condition factor (K), the Sex-ratio, the fecundity, the diameter of eggs revealed that this species spawns throughout the year but the main breeding period was in raining season. Sex-ratio observed was in favour of females (1: 1. 14; X2 = 2.26; p > 0.05). The percentage of mature specimens by sexes was calculated for each size class. Total length at first maturity was 21.06 cm for females and 20.21cm for males. The ripe ovaries contained 39883-814757 eggs. The relative fecundity was 216-1979 eggs per g of body weight of females. And the mean diameter of eggs is 336 ±138 microns

Reproduction De Heterotis Niloticus (Cuvier, 1829) De La Riviere Agneby (Cote d’Ivoire)

The reproductive biology of Heterotis niloticus has been studied from monthly samples taken from artisanal fishing on the Agneby river during the period june 2013 to May 2015. The whole sample consisted of 498 specimens of which 269 females and 229 males were examined. Sex-ratio observed was in favour of females (1: 1.17; X2 = 3.21; p > 0.05). The monthly evolution of the gonado-somatic index (GSI), the liver-somatic index (LSI), the condition factor (K) and maturation stages suggests that this fish has two periods of reproduction. The two periods were respectively from june to august and from november to december. The standard length at first sexual maturity was 490.6 mm for females and 436.3 mm for males. The absolute fecundity was ranged from 5424 to 25591 oocytes in females of 595 mm to 780 mm standard length. The relative fecundity was 3752± 1491 oocytes/kg of female