Modelling catch per unit effort of the Black Volta near the Bui dam in Ghana

The chlorophyll a concentration and water level of the Black Volta near the Bui dam were studied in relation to fish production as measured by catch per unit effort (CPUE) between February 2011 and December 2012. The primary objective was to develop a simple linear regression model for predicting CPUE levels. The mean estimated CPUE for 2011 and 2012 was lower (6.23 kg canoe⁻¹ day⁻¹) in the postwet season than in the dry season (10.86 kg canoe⁻¹ day⁻¹) with a mean of 7.95 kg canoe⁻¹ day⁻¹. Hence, the dry season was the most important season for fish catches in the study area. Predictor variables that significantly explained CPUE levels were chlorophyll a (positive correlation) and water level (negative correlation) (P = 0.0002). The model was validated with independent data from the same Black Volta in 2011 and 2012. This model, CPUE = (0.062 × chlorophyll a) − (0.456 × water level) + 3.363, explained 91% CPUE variability. Independent validation indicated that the model had the potential to predict CPUE (as a measure of fish production) in the Black Volta near the Bui dam. Hence, the model is also a valuable tool to predict future trends in the CPUE levels of the Black Volta.