Biologie de la reproduction du Cichlidae Tylochromis jentinki dans la lagune Ébrié (Côte d'Ivoire)

Von Atsé, Boua C & K.J. Konan

Cybium, vol. 33 (n. 1): pp 11-19 (31-März-2009)

" This work describes some aspects of reproductive biology of the Cichlidae Tylochromis jentinki(Steindachner, 1895) in Ébrié lagoon (Ivory Coast). Fish were sampled with gill nets from February 2004 to January 2006. The whole sample consisted in 1850 specimens with standard length (SL) ranging from 75 to 235 mm and weight from 11.90 to 407.57 g. Immediately after capture, SL was taken to the nearest 1 mm, and total body weight (TW) and eviscerated body weight (EW) to the nearest 0.1g. The gonads and the liver were then removed, weighed to the nearest 0.001 g. The reproductive period of T. jentinki was established by analysing the temporal evolution in the frequency of the maturity stages and monthly variations in the gonadosomatic index (GSI), the hepatosomatic index (HSI) and the condition factor (K). Sex-ratio was established taking into account the sex determinations. The sizes at which 50% of the specimens became mature (L50) were estimated by means of logistic function that was fitted to the proportion of the mature individuals using a nonlinear regression. The sex-ratio for the overall sample showed a statistically significant predominance of females (1: 1.2; χ2 = 14.54; n = 1850; p < 0.05). The first sexual maturity size was 118 mm (SL) for males and 126 mm for females. The smallest mature female was 81 mm (SL) while the smallest mature male was 93 mm (SL). Both monthly gonadosomatic index and macroscopically determined gonad stages strongly indicate that Tylochromis jentinki in Ébrié lagoon spawns in April and from October to December. Tylochromis jentinki exhibits a breeding strategy in relation to the lowest salinity and the food variability conditions. The reproduction of this species was synchronized to take advantage of the beneficial optimal environmental conditions in order to ensure greatest survival of the young. During oocyte growth, the hepatosomatic index and the condition factor increased. On the other hand, spawning leads to a decrease of HSI and K. Absolute fecundity was 105 and 465 oocytes for females of 114 and 230 mm (SL). The mean relative fecundity was 2223 ± 765 ovocytes Kg-1 of females. The mean oocyte diameter was 5.51 ± 0.27 mm at spawning "

Klassifizierung: Verhalten, Afrika.

Sprache: French

Atsé, Boua C & K.J. Konan. 2009. "Biologie de la reproduction du Cichlidae Tylochromis jentinki dans la lagune Ébrié (Côte d'Ivoire)". Cybium. vol. 33 (n. 1): pp 11-19 (crc02513) (Kurzfassung)