Reproductive Biology of the African Lungfish (Protopterus annectens) in the Flood Plains of Cross River State

This study examines the reproductive biology of the African lungfish Protopterus annectens in the floodplain ecosystems of Cross River State, located in Nigeria's South South geopolitical zone. Protopterus annectens is a commercially harvested and ecologically unique fish exhibiting bimodal respiration and aestivation, yet reproductive data from Nigerian populations are scarce. Fish were sampled from artisanal fishers and directly from floodplains during both flood and recession phases over a ten-month period. Gonads were dissected from 120 specimens (67 female, 53 male), weighed, and staged histologically. Gonadosomatic index, fecundity, oocyte diameter distribution, and spawning period were assessed. Gonadosomatic indices peaked during the wet season recession phase (October to November), indicating spawning in burrows as floodwaters recede. Mean absolute fecundity was 624 eggs per female, relatively low compared to most teleosts and consistent with the high parental investment strategy typical of lungfish. Oocyte diameter at maturity averaged 3.8 mm. Sex ratio was 1:1.27 in favour of females. Males showed aggressive territorial behaviour around burrow sites during spawning season. Testes histology confirmed synchronised spermiogenesis with gonadal development. The study provides the first detailed reproductive characterisation of Protopterus annectens from Cross River State and recommends seasonal fishing restrictions during the October to November spawning period to prevent further population decline. Keywords: Protopterus annectens, reproductive biology, African lungfish, Cross River State, gonadosomatic index.