Research Article

Culturally important freshwater Lakes in the central Niger Delta, Nigeria: Fish assemblage and diversity assessment

Anwana E.D *¹ and Nwosu F.M²

¹Department of Botany and Ecological Studies, University of Uyo, PMB 1017 Uyo, Nigeria

²Institute of Oceanography, University of Calabar, PMB 1115, Calabar, Nigeria

* Corresponding Author E-mail: e_anwana@yahoo.co.uk

Accepted 20 February 2014

Abstract

Freshwater systems shelter a vast array of biodiversity and are considered as one of the world’s richest habitats for fish species, molluscs and other aquatic animal species. However these systems are imperilled by reclamation, drainage and pollution, particularly in the coastal states of the Niger Delta region, Nigeria; where the influx of oil companies opportunists struggle for available resources. But, within several communities of the region, freshwater lakes exist that have restricted access. These lakes are harvested periodically, ranging from a minimum of once in two years to maximum of once in ten years, with strict observance of rules based on indigenous belief systems. Drawing from findings of an interdisciplinary research conducted within the Niger Delta floodplain, this paper examines the fish assemblage and diversity of four lakes in Bayelsa State. Two lakes were assessed from the southern fringes of the inland flood zone of Osiama (Lake Adigbe) and Sabagreia (Lake Efi) communities and two lakes from the marsh forest ecozone of Biseni (Lakes Esiribi and Obaa). Preliminary physico-chemical analyses of the four lakes show slight variation between lakes, with pH range of 4.95 – 6.87. In consonance with cultural fishing practices observed in these lakes, a combination of cast and drag net samples with different mesh sizes (35 – 130mm), were acquired. A total of thirty eight (38) species from seventeen (17) Families and seven (7) Orders were identified. In the four lakes studied, the genus Citharinus citharus showed overall dominance, followed by Synodontis membranaceous. Comparisons across lakes show similarity in the assemblage of fish species, with more diversity in the three lakes having secchi depths > 2 metres. The management of these lakes by indigenous systems is commendable going by its sustainability and the absence of resources needed for enforcing conventional methods. Hence, the management of these lakes and similar tagged lakes using cultural systems could ultimately be the key to sustainable management of aquatic resources within the region.

Keywords: Freshwater Lakes, Fish diversity, Bayelsa State