Assessing the impacts of feed and species composition on greenhouse gas emission from freshwater aquaculture systems in Bangladesh

Abstract

Bangladesh, a significant contributor to the global aquaculture sector, is considered as a significant source of greenhouse gas (GHG) emissions but no measured data have been reported yet. This study investigates GHG emissions from four prevalent freshwater aquaculture systems in Mymensingh, Bangladesh, focusing on Indian major carps (IMC), Pangasius catfish (PG), Climbing perch (CP) and Tilapia (T). The research aimed to quantify and compare the concentrations in water and emissions of three major GHGs (CO2, CH4, and N2O) from these systems, providing an analysis of the impacts of freshwater aquaculture to climate change in the region. The study measured dissolved GHG concentrations and emissions to the atmosphere during February to September 2024, aligns with the transition from the dry winter season to the pre-monsoon season in Bangladesh. The results revealed that PG systems exhibited significantly higher GHG emissions, primarily due to the extensive use of sinking feeds that led to increased organic waste and methanogenesis. In contrast, the IMC and T systems, utilizing more efficient floating feeds, showed comparatively lower emissions. The dissolved gas concentration analysis further complemented the surface gas emissions data, offering a holistic understanding of emissions from aquaculture ponds. The PG ponds had higher mineral nitrogen and electrical conductivity with lower dissolved oxygen corresponded well with higher methane and N2O emissions. The results suggest that optimizing feed composition and management can substantially reduce the aquaculture sector's impacts on climate change. By providing a detailed understanding of the GHG emissions from different aquaculture systems, this research contributes valuable insights for policymakers, industry stakeholders, and environmental scientists. It underscores the need for sustainable aquaculture practices and offers a foundation for developing strategies to mitigate the impacts of fish farming to climate change, while ensuring the sector's sustainability and its contribution to global food security.