Enhancing local fish production through cage aquaculture on the Volta Lake: Impacts on capture fisheries

Abstract

Aquaculture is a preferred alternative to increasing global fish production than management of wild stocks. Its practice is, however, known to have ecological impacts if not managed well. The study was conducted to determine the potential impact of cage culture of fish on food preference of wild fish. A case study was carried out in the Volta Lake at Kpeve-Tornu using Chrysichthys species which is one of the dominant species found in the Lake. Sampling was done for eight months from August 2013 to March 2014. An area of the lake with no fish farming activities was used as a control. The stomachs of 130 Chrysichthys specimens were analyzed. Importance of each food item was determined using frequency of occurrence method. The dominant food items identified were chironomid larvae and detritus; occurring in 27.3% and 36.4% respectively of the stomach contents at the cage culture site and 63.9% and 52.8% at the control site respectively. Plant parts also occurred in 36.4% of the stomachs at the cage culture site. Lampsilis species, a freshwater mussel, was found only in the stomachs at the control site and it occurred in 41.7% of them. Cage culture in the Volta Lake impacted on the food preference of Chrysichthys species by influencing the availability and abundance of food items. As promising as cage culture is in Ghana; in supplementing production from capture fisheries, it must be done on a scale that keeps its ecological impacts in the Volta Lake in control.