Estimation of waste outputs by a rainbow trout cage farm using a nutritional approach and monitoring of lake water quality

Fish-PrFEQ model is a valuable cage management tool that allows realistic estimation of waste outputs for cage farms and can be used to examine effect of management and feeding practices on waste outputs. However, the model is of limited use as a lake management tool, as it does not consider effects and fate of wastes released by fish. Similarly, reliance on periodic water quality monitoring at stations near cage farms may not be protective of the environment, as our results demonstrate that rapid diffusion, uptake, transformation and removal of nutrients resulted in water quality measures that were relatively insensitive to cage loading. Combining the Fish-PrFEQ model with a consideration of assimilative capacity of the system in addition to the monitoring of chemical and biological variables of the lake is recommended for environmental impact assessment of cage culture operations.