Fish species composition, distribution and abundance and gillnet fisheries in Ikere gorge, Nigeria

Adeosun, F. Idowu*, Omoniyi, I.Tunde, Akegbejo-Samsons, Yemi, Alegbeleye, W. Olusegun
Federal University of Agriculture, PMB 2240 Abeokuta, Ogun State, Nigeria

Overfishing is a major problem in fisheries as fishermen without adequate knowledge of the composition, distribution and abundance of fish species continuously fish in water bodies using various fishing gears thereby depleting the stock. Here, we carried out the ecological study of Ikere gorge between January 2004 and December 2005 to assess the fish resources of the gorge and the gear commonly used by fish farmers in the gorge. We collected data on fish composition, abundance and gear used from four sampling stations. Thirty-four (34) fish species belonging to thirteen (13) families were present in the gorge. Our findings revealed that Bagridae (25.1%), Cichlidae (37.1%) and Mormyridae (14.5%) were most abundant families contributing 76.7% by number and 75% by weight of the total catch followed by Characidae (9.6%), Cyprinidae (7%) and Centropomidae (3%) constituting (19.6%) by number and 8.7% by weight. Schilbedae (1.1%) Clarridae (0.8%), Hepsetidae (0.7%0, Mochokidae (0.6%), Channidae (0.5%), Icthyoboridae (0.2%) and Malapteruridae (0.1%) were least represented. We found out that commonly used gears were cast net, traps, bamboo stems, spears, gura net and gillnet which was the major fishing gears in used. Also, the gillnet fisheries observed showed the sensitivity of experimental gillnets mesh sizes to different fish species. 78.4mm, 112mm, 67.2mm mesh sizes were efficient in catching Chrysichthys. nigrodigitatus Lates niloticus and the cichlids respectively. The study contributed to baseline data on the fish composition and distribution and gear selectivity on fish catch. Thus aiding fisheries policy makers in the management of this water body.