Resource consumption assessment of Pangasius aquaculture in the Mekong delta, Vietnam

In light of full exploitation and overexploitation of marine fish stocks on a global scale, aquaculture has gained prominence to meet the increasing fish demand induced by population growth and rising incomes. Pangasius production in Vietnam is widely known as a success story in the aquaculture sector due to a tremendous expansion by volume and value in recent years. However, a growing concern has arisen about the environmental sustainability of this system, particularly in terms of resource extraction. We addressed this issue here by expressing all resources in one common unit: Joules of exergy. Exergy is defined as the amount of maximum useful energy obtained from a resource. Analysis using this metric was performed at process level through Exergy Analysis (EA; Table 1) and from a life cycle perspective via quantification of the Cumulative Exergy Extraction from the Natural Environment (CEENE; Figure 1), which was subdivided into seven resource categories. This allows one to identify hotspots over the life cycle stages, including feed production, juvenile production and fish cultivation. Results show that the largest contributors were the feed input (73% of the total CEENE) and the water renewal of the ponds (25%), mainly assigned to the farm phase (90%). Land (62%) and water (31%) account for the main share in the resource footprint, which is reasoned by the agricultural production of the crop-based feed ingredients and the high water exchange in pond farming, respectively. Improvements therefore should focus on lowering water input into the ponds and increasing the efficiency of the feed supply chain. The latter option represents a great challenge while the former could be feasible through the application of a recirculating aquaculture system (RAS). Further research is needed to explore whether RAS is a feasible sustainable alternative. Overall, Vietnamese farm and feed mill managers play a key role in improving the environmental performance of Pangasius products. Focus should not only lay on their own farming and processing, but also on the selection of their feed suppliers