Diversity and Abundance of Fish Species in Gbedikere Lake, Bassa, Kogi State

Abstract

Experimental gill net and artisanal fishery of Gbedikere Lake, Bassa, Kogi State, Nigeria were assessed between October 2006 and September 2008. Fish species diversity was found to be low; twelve species representing ten families were identified namely, Protopteridae, Mormyridae, Clariidae, Mochokidae, Cichlidae, Malapteruridae, Osteoglossidae, Gymnarcidae and Citharinidae. Cichlids were numerically most dominant of the catches (Oreochromis niloticus, (17.90%) and Tilapia zilli (13.01%). In terms of biomass the trend was found to be the same. Other species of numerical importance were Heterotis niloticus (15.56%), Clarias gariepinus (13.16%), Gymnarchus niloticus (8.78%), Heterobranchus bidorsalis (7.14%), Synodontis nigrita (6.69%), Mormyrus rume(5.68%), Citharinus citharus(3.91%), Labeo senegalensis(2.93%) and Protopterus annectens (2.74%). Oreochromis niloticus dominated the catches in all the months, contributing over 17.90% to catches by number and between 13.40% by weight throughout the duration of the sampling. The mean annual yield obtained through catch assessment surveys during the study was 240.2 tons. A log transformed length-weight regression analysis for four of the economically most important species revealed the following linear relationships. Log W = -1.2366 + 2.8028 Log L (r = 0.9798) for Heterotis niloticus; Log W = -1.7525 +3.047 Log L (r =0.9361) for Oreochromis niloticus; Log W = -2.3449 + 3.496 Log L (r = 0.9548), for Tilapia zilli and Log W =-1.0306 + 2.321 Log L (r =0.9351) for Clarias gariepinus.