Greenhouse Gasses Emissions (GHG) associated with aquaculture accounts for approximately 0.5% of global anthropogenic GHG emissions but they can become more important as the sector continues to grow. Most of aquaculture-related emissions are associated with the production and transportation of aquafeeds (50-60% of the carbon footprint). Extraction of fishmeal and fish oil, main ingredients in aquafeeds, is very energy consuming. Moreover, raw materials are often sourced in continents different from where they are used and the carbon footprint associated with transportation is significant.
Nitrous oxide (N2O) from microbial nitrification and denitrification is another source of GHG associated with aquaculture. Moreover, energy use in the fish farm (pumps and lights) and to transport the fish harvested also generates emissions. The most effective way to reduce aquaculture-related emissions is the use of sustainable and locally-sourced ingredients for feed. Use of extractive species to remove nitrates from the effluents, use of renewable energy sources, correct by-products management and use of AI and remote sensing tools for standard operations are other interventions that help to reduce emissions. Different research projects aimed at developing solutions to improve aquaculture sustainability are presented. Alternative sources of protein and lipids for aquafeeds were tested on different Mediterranean species. Fish farming was coupled with production of additional biomasses, consisting of extractive species, with the aim of removing nutrients from the aquaculture effluents. This has the double benefit of reducing water pollution and N2 emissions. AI tools to automate feeding and biomass assessment were tested in a farm in Tunisia, powered by solar panels. Finally, emissions associated with production of fishmeal and fish oil from tuna by-products, were estimated through life cycle assessment and compared with the emissions of traditional sources of proteins and lipids. GHG produced through incineration of by-products (alternative management method) were also estimated.
In Tunisia, live streaming from the cage allowed operators to visualize the conditions inside the cages remotely, limiting boat trips and improving the performance of the farm. Using AI estimation software also helps farmers to save approximately 56 hrs of work per cage/cycle.
Extractive species grown on aquaculture effluents can remove more than 90% of nitrogen from the water, drastically reducing the release of N2 and producing additional valuable biomass. Incineration of 6 tons of tuna by-product has a single score of 176 Pts, while the use of the same biomass to produce fishmeal and fish oil has a single score equal to 112 Pts. Replacing fossil fuel with solar energy in the processing plant, allows 90% reduction of emission. Seabass and whiteleg shrimps fed with aquafeed including tuna by-products as a source of protein and lipids, performed as well as when fed with commercial aquafeeds.
Overall, all the approaches taken were successful in improving the sustainability of aquaculture. Emissions from this sector can be reduced substantially by integrating new available technologies in the production process.