Sexual maturation, spawning activity and fecundity ofDrepane africana (Osório, 1892) off the Niger Delta Coast, Nigeria

Abstract

Drepane africana is an economically important fish species in Nigerian brackish and marine waters, also prominent in shrimping trawl catches and coastal artisanal shrimping. Information on the maturation and spawning activity of D. africana is needed to establish necessary knowledge on its reproduction off the Niger Delta coast to promote sustainable exploitation. The sex ratio, gonadal stages, fecundity, and gonadosomatic index (GSI) of D. africana were studied between April 2013 and September 2015 (n = 2,124) to establish its sexual maturation and spawning activity off the Niger Delta coast. Sex ratio 1.5: 1 (female: male) was significantly different (p < 0.05). Fecundity ranged from 13,000 to 204,516 eggs with mean of 121,770±76,507 for fish of 10.2 – 39.4cm (24.6±5.5) and 17.9 – 1,350g (381±302.5) body weight and gonad weight range of 16.0 – 43.0g (mean 26.0±4.2). Gonadosomatic indices were higher in females 0.8 – 4.9% (2.3±1.2) than in males 0.2 – 1.6% (0.6 ±0.4). The GSI was high between August - February with the peak in November for this species. Five gonadal stages were observed. The species is an annual spawner; its exploitation during the spawning season should be regulated for proper management in the study area.