Towards more efficient fish farming systems in the Sistan region of Iran: An emergy-based analysis

The environmental and economic inputs of three different fish farming methods, (semi-natural, concrete, and galvanised ponds) were investigated in a region with a hot and dry climate and a severe water shortage. The data were collected in 2020 through direct interviews with fish farmers, as well as regional weather information. The inputs and outputs of each system, both environmental and purchased, as well as the water quality parameters and fish growth rates, were also recorded. Emergy analysis was applied to assess the economic, and environmental aspects of these systems and to compare their performance and sustainability. According to the emergy efficiency indicators (Tr and SpE), concrete ponds had a higher efficiency for fish farming than the other two systems. Semi-natural fish farming was sustainable, as shown by the emergy yield ratio, which measures the system's reliance on environmental inputs. Semi-natural ponds had an economic advantage (O/I, BN, O/IEmV and BNEmV) over concrete and galvanised fish farming, because they used environmental inputs more effectively for fish rearing. Environmental efficiency can be improved by taking suitable management actions, such as increasing the size of fingerlings, while economic efficiency can be enhanced by enlarging the scale of fish farms. At the same time, using economic inputs more efficiently in concrete and galvanised ponds can boost both their sustainability and economic efficiency.