Parameterization and calibration of a model for fish production in seasonal wetland fish ponds (‘Fingerponds ’)

A dynamic model was developed to simulate fish growth in a seasonal wetland fish pond ‘Fingerpond’. The model describes fish growth based on the natural food production. It incorporates key environmental and management factors: pond water depth, food availability, fish stocking densities, initial fish and fingerling weights at stocking, reproduction rate, manure type and application rates. The model was calibrated for two types of Fingerponds distinguished by differences in their hydrological regimes: ponds with fairly constant water levels (functional culture period 300 days); and those affected by inflowing rivers with decreasing water levels (200 days functional period). The stocked fish and fingerling were fed with natural organic manure (chicken) applied fortnightly at a rate of 1,042 kg ha −1 .The model was able to capture the dynamics of hydrology, nutrients and fish in the two types of Fingerponds demonstrating that similar fundamental processes underlie fish production in these systems. Model fish yields of up to 2,800 kg ha −1 were achievable. Water quality predictions such as chlorophyll a and dissolved inorganic nitrogen concentrations were comparable to field measurements. Using the model, nitrogen budgets for Fingerponds were calculated and quantitative estimates of all process flows were given. The model is preliminary and should be subjected to sensitivity analysis and validation before it can be used as a management tool. Main knowledge gaps pertain to light limitation of primary productivity and the food selectivity of the tilapia fish and their fingerlings. In its current state, the model is a research tool that identifies knowledge gaps and can be applied to frame hypotheses for further applied research. According to the outputs, the model can contribute to improving the management of Fingerponds.