Spatial distribution of Nile perch using acoustic methods

Abstract

Lake Victoria supports Africa's largest fishery, being Nile perch the main contributor for the fishery revenues. Alerts for decreases in the commercial catches of Nile perch were reported during the mid 1990s. According to Kolding et al. (2008b), fish stocks are being affected mainly by eutrophication processes. The purpose of this work is to study if there is a relation between Nile perch spatial distribution and limnological data, in order to estimate the effects of enhanced eutrophication in the stock distribution. Acoustic data was used to obtain information on the Nile perch spatial distribution in association with limnological data (oxygen, chlorophyll a and temperature). Study limitations did not allow to conclude on relations between Nile perch densities and limnological data. However the results show a relation between Nile perch size and oxygen, and between Nile perch size and chlorophyll (for the three strata combined, as for the deep and inshore strata). Temperature showed to have no relation with fish size.