Sustainability assessment on different crops for aquaponics : an evaluation table for growing crops using wastewater from juvenile Atlantic salmon in RAS

Abstract: Aquaculture is an expanding industry, supplying closer to 50% of the total fish consumption. Commercialized fish production faces sustainability challenges which are important to address. Aquaponics uses wastewater from aquaculture to grow plants using hydroponics. This is a step towards making the industry more sustainable, but the practice is not straightforward. The plants and the fish thrive at different environmental conditions and not all plants can be grown using aquaponics. The aim of this study was to use literature to find a user-friendly evaluation method and to find suitable crops to grow in a juvenile Atlantic salmon aquaponic system in Iceland. This study used a Multi-Criteria Decision Analysis Method to compare the suitability of different crops for hydro- or aquaponics. The evaluation was based on the three sustainability pillars from the United Nations: economical sustainability, social sustainability and environmental sustainability. An evaluation table was constructed, and three crops were compared for aquaponics in view of these sustainability pillars: basil, lettuce, and soybean. The crops were graded using a score function. The basil received the highest total score and was deemed most suitable for an aquaponic system where juvenile Atlantic salmon is farmed. The basil received a much higher grade in economical sustainability which resulted in it receiving the highest total grade. Lettuce scored the highest in social and environmental sustainability indicating that it is also suitable for aquaponic purposes. Soybean was found to be unsuitable at this point. A sensitivity analysis was performed in the form of “worst case scenario” using the lowest values found in the literature. It revealed that economic sustainability was a controlling factor for the final grading. The evaluation table itself was found to be easy to modify to the user’s needs where both subcategories and weights can be adjusted. It can be applied for other sustainability assessments comparing the suitability of several crops for hydro- or aquaculture and even agriculture. Further studies could include constructing an experiment using juvenile Atlantic salmon in an aquaponic system and comparing several crops in order to get more accurate values on the environmental parameters.