Icthyofauna composition and biodiversity of Okomu Wetland, Edo State, Southern Nigeria

Abstract

Fish and fishery products significantly contribute to global food security and nutritional needs. The present study was carried out to determine fish biodiversity of Okomu National Park, Niger Delta Region of Nigeria. The icthyofauna composition of the wetland was studied monthly from August to October, 2018 to compare the presence, distribution and abundance of fish species in the lotic (Okomu River and Arakhuan Stream) and lentic water bodies within the ecosystem. Fish samples were collected with fishing nets of various mesh sizes using the standard capture and return technique. The results of the study revealed 71 fish specimens belonging to six (6) Orders, eight (8) Families and twelve (12) species. The fish species recorded included: Xenomystus nigri, Petrocephalus bovei, Gnathonemus petersii, Pelmatochromis pulcher, Oreochromis aureus, Tilapia zilli, Tilapia dageti, Micralestes elongates, Citharinops distichodoides, Parachanna africana, Erpetoichthys calabaricus and Malapterurus electricus. No fish sample was observed in the temporary ponds under investigation. This may be due to predation, seasonality, and water quality. However, the lotic systems supported fish population, where 10 fish specimens were obtained from Arakhuan Stream while Okomu River had 61 specimens. The family, Cichlidae dominated in the study area and constituted Tilapia zilli (22.5%), Tilapia dageti (18.3%) and Oreochromis niloticus (16.9%) of the total catch. The study demonstrated that the lotic segment of the Okomu Wetland supported fish diversity and provided valuable baseline information for future research.