The prevalence of helminthofauna and fecundity studies in west African lungfish, Protepterus annectens Owen, 1839 (Dipteriformes: Lepidoserinidae) in river Anambra, Nigeria

Abstract

An investigation was conducted on the helminthofauna and some aspects of reproductive biology of the West African lungfish, Protopterus annectens in River Anambra, Nigeria, between May and July, 2008. The sample comprised forty two fishes purchased from fishermen and fish mongers at Otuocha fish market, a major fish landing location in the Anambra River Basin. The sex composition of the sample which was 1:41 (male: female) is thought to reflect a preponderance of female fish in the natural population of P. annectens in the river system. Heterorchis protopteri, a digenean, was the only helminth parasite recovered, infesting 6 (six) out of the 42 fish.33 worms were recovered, giving a prevalence of 14.29 %, mean intensity of infection of 5.5 and mean abundance of 0.8 for the parasite in the fish population. The infection parameters increased with size of fish (weight and length). No parasite was recovered from the lone male fish examined, and this could be attributed to sample size. H. protopteri is reported from P. annectens in Nigeria for the first time. All the female fish examined were gravid while the lone male fish had ripe testes which indicate that P.annectens spawns in the river system in the wet season. Fecundity of the species was estimated to be about 1423 eggs per female and P. annectens is categorized as a mesofecund species. It is suggested that some form of regulation of cropping of P. annectens in the river system should be put in place pending a clearer understanding of its ecology, in order to reduce the chances of harming the recovery capacity of the species.

Keywords: Protopterus annectens, River Anambra, Heterorchis protopteri, fecundity, spawning.