Reducing the Carbon Footprint from Pond Aquaculture in a Changing World

The contribution of aquaculture to the total greenhouse gas (GHG) emission from agriculture is small. However, it is a major concern as aquaculture is one of the fastest growing agricultural activities. Life cycle analysis (LCA) indicates that formulated feed is the major contributor to GHG emission from aquaculture. Depending on the boundaries set for the LCA, the contribution from feed to GHG emission varies between 24 and 93%. Therefore, insight in the mechanisms of GHG emission is important. Carbon dioxide (CO 2 ) is the major contributor to global warming, but other gases, of which nitrous oxide (N 2 O) and methane (CH 4 ) are the most important gases, are responsible for close to 30% of global warming. All water bodies release GHG, and the difference in emission between a natural water body and an aquaculture pond should be considered. Generating more in-depth insight in GHG emissions from aquaculture production systems in function of farm system design and operation is needed to develop strategies to reduce emissions from aquaculture farms. Ecological intensification by growing fish/shrimp within the carrying capacity of the pond, or using renewable energy such as solar power for farm operation, and using more efficient equipment, can help to reduce GHG emissions. The nutritious pond concept is providing nutrient inputs to ponds, aiming for a metabolic waste/faeces composition resulting from feeding that is easily degradable by microbiota and hence stimulates the natural food web of the pond. A dual-purpose feed is formulated that feed the fish directly and indirectly, as feed and natural food, respectively. The concept aims to reach the maximum production potential within the carrying capacity of the pond and might even be able to increase the carrying capacity through the efficient biogeochemical cycling of nutrients. The fact that in semi-intensive tilapia ponds fed nutritious pond feed, the protein contained in harvested fish was more than 70% of the protein fed, shows the nutrient utilization efficiency is high. How nutritious pond farming will influence GHG emissions from ponds needs further investigation.