The Lake Volta Project: Outcomes and Capacity Building:

Project Approach:

Lake Volta Landsat

Aquaculture uses and transforms resources into commodities valued by society but when badly managed it can have negative environmental impacts with social and economic consequences. Wastes from aquaculture are largely generated from uneaten foods, faecal and other metabolites. Quantities of waste depositing under fish cages at intensively managed farms have been found to be a magnitude higher than those recorded at control sites or in undisturbed water bodies (Beveridge, 2004). Studies have also shown that the extent of waste accumulation in aquaculture is variable and depends on local site conditions, the species being cultured, feed type and management. Preliminary assessment of environmental impacts of cage aquaculture on the Volta Lake by Asmah et al. (2011) yielded little information as the study was limited to water quality monitoring due to limited financial and logistical support for the project.

This project uses questionnaire surveys to obtain information on the quantities and types of inputs being applied by the fish farmers and management styles of the farms. Sampling sites in the lake were selected to represent different environmental conditions and farming practices. Monthly hydrological data (flow rates, water level, water depth, flooding times and duration) and water samples have been collected for analysis, determining pH, water temperature, suspended solids, turbidity, colour, total dissolved solids, transparency, nutrients and the trace metals; copper, zinc, manganese and iron which have been identified as fish feed additives (Chou et al. 2002). At each selected site, water samples have been collected from the surface, mid depth and near-bottom of the Lake over a two year period. A multifunction field meter and other instrimenttation provided by the project have facilitated data logging and real time analysis of some parameters in the field. Water samples for the other water quality parameters were preserved for analysisi at the Water Research Institute laboratories. Sediment samples have been collected quarterly for analysis, including grain size distribution, particulate organic inputs, sulphide and nutrients. Quantities of wastes discharged to the environment have been estimated using a mass balance approach and verified using sediment traps.