ASSESSMENT OF SITE SUITABILITY FOR CAGE FISH FARMING IN SELECTED BAYS OF LAKE VICTORIA, UGANDA

Abstract

Cage culture is considered an alternative to increasing fish production that can provide employment, income and food. However, its unplanned expansion could result in negative environmental and social impacts. This study evaluated suitability of sites for cage farming on two bays in Lake Victoria (Lwanjaba and Busambaga) and assessed community perceptions towards fish cage farming. Water quality data including water temperature, water depth, water flow rate, pH and dissolved oxygen were obtained at 40 points at each of the two bays. Quantum GIS was used to map for sampling these water quality parameters. Socio-economic issues such as other competing uses and community perceptions were examined through Focus Group Discussions (FGDs) and Key Informant Interviews (KIIs). Temperature generally increased with depth (from 27.1±1.1°C at the surface to 27.4±0.20C at two-meter depth in Lwanjaba Bay and from 26.4± 0.6°C at the surface to 27.0±0.20C at two-meter depth in Busambaga Bay). pH was observed to be constant at all depths (7.9±0.3 in Lwanjaba Bay and 7.7±0.5 in Busambaga Bay). Dissolved oxygen concentration increased minimally with depth (from 13.4±2.4 mgL-1 at the

surface to 13.5±2.4 mgl-1

at two-meter depth in Lwanjaba Bay and from 12.6± 1.5 mgL-1 at the surface to 14.2±5.6 mgl-l at two-meter depth in Busambaga Bay). Flow rate decreased with depth (from 27.0 ±15.6 cms-1

at the surface to 23.8±9.7 cms-1 at two-meter depth in Lwanjaba Bay and

from 34.2±13.4 cms-1

at the surface to 28.7±10.6 cms-1

at two-meter depth in Busambaga Bay). All parameters measured were within the recommended values (dissolved oxygen > 5 mgl -1 , pH

range 6.5-9, temperature range 27-320C and flow rate of 10-100 cms-1

). Results indicate that the bays are generally suitable for cage establishments. Therefore, cage site suitability studies and awareness creation among communities are important in ensuring environmental sustainability and amicable co-existence of cage fish farming with other water uses.