Assessment of fish stock and plankton of Oli River, Kainji Lake National Park, Nigeria

Abstract

Fish stock, Physico-chemical parameters and primary productivity of Oli River were determined using experimental gill-net, standard limnological procedures and depth strata techniques. Thirty six (36) different fish species from 15 families were recorded from the river during the survey. The catches were dominated by Schilbeids with Schilbe mystus dominating the over-all catch composition. The yield estimate from the river based on experimental gill net sampling was 30.27 kg/1000 m2, which translates to an average fish production of 48 kg/ha. Eighteen (18) and fourteen(14) species of phytoplankton and zooplankton respectively were recorded from the river. This is quite high and it is an indication that the river has abundant natural fish food. Using the Morpho-Edaphic Index (MEI) that is based on the river conductivity and mean depth, the potential fish yield of the river was 57.38 kg/ha. This yield which is higher than the actual production indicates and strengthens the need for proper management of the river to improve its current fish production.