Abstract:Since the 1980s, China's aquaculture industry has experienced rapid development and sustained growth in aquaculture production, not only providing large quantities of high-quality protein for humans but also becoming an important supplement to ensure global food security. The salinity adaptation range of Penaeus vannamei is extensive; therefore, it can be cultured in both saline and freshwater environments. China has 690 million acres of saline water resources, offering considerable potential for the aquaculture of P. vannamei. The ongoing aquaculture boom incurs environmental costs, while providing protein to the fast-growing human population. Carbon emissions are generated during aquaculture; thus, assessing the carbon footprint of seafood aquaculture is essential for establishing targeted emission reduction and carbon sink enhancement strategies, vital for achieving the "Carbon Peak and Carbon Neutrality" goals. The carbon footprint is defined as the total amount of greenhouse gases emitted, either directly or indirectly, by an individual, organization, event, or product throughout its life cycle and is typically expressed in terms of CO2 equivalents (CO2e). This metric provides a comprehensive and intuitive understanding of the environmental impacts of human activities and facilitates the development of targeted emission reduction and carbon sink enhancement strategies. The most commonly employed method for carbon footprint accounting is the Life Cycle Assessment (LCA), which consists of four key parts: (1) target and scope definition, (2) inventory analysis, (3) impact assessment, and (4) interpretation of results. Here, the carbon footprint of P. vannamei pond culture was assessed using the "gate-to-gate" LCA methodology, based on primary data from on-site monitoring of culture ponds and aquaculture enterprises in Shandong Province. The carbon footprint of producing 1 kg of P. vannamei was 5.60 kgCO2e, with total carbon emissions of 7.69 kgCO2e. These emissions primarily stem from the use of chicken manure, lime, and feed, whereas the net carbon uptake by the pond ecosystem—attributed to the abundance of various algal species—is 2.09 kgCO2e. Notably, carbon emissions from the aquaculture process alone reached 7.42 kgCO2e, constituting 96.5% of total emissions, while pond construction and decommissioning emissions were only 0.27 kgCO2e, accounting for 3.5%. Among the sources of carbon emissions, chicken manure used for fertilization represented the largest share, contributing 5.62 kgCO2e and accounting for 73.0% of the total emissions during the shrimp culture phase. This was followed by compounded feeds, contributing 0.87 kgCO2e and representing 11.3% of the total emissions, while quicklime accounted for 10.7% of the total emissions at 0.82 kgCO2e. Additionally, diesel fuel and materials such as electricity and polyethylene contribute ~5% of the total carbon emissions. The predominant farming methods of P. vannamei in China include factory farming, semi-intensive ponds, small-shed cultures, and pond aquaculture. Existing research analysis indicates that the carbon footprint of 1 kg of P. vannamei farmed year-on-year with different farming methods are in the following order: large surface culture (5.60 kgCO2e) < small shed culture (18.25 kgCO2e) < semi-intensive ponds (52.3 kgCO2e) < factory farming (198 kgCO2e). Therefore, it is necessary to explore a win-win aquaculture model for economic and ecological benefits from a multidimensional perspective of green, sustainable, and efficient aquaculture. Under equivalent intake conditions, substituting seafood products with P. vannamei with low-carbon emissions can effectively reduce overall carbon emissions. Several recommendations have been proposed to mitigate emissions from P. vannamei aquaculture in ponds with large water surfaces. First, the excessive use of chicken manure as fertilizer—as indicated by the pond monitoring results—should be moderated to optimize application rates. Currently, farming enterprises often apply chicken manure without adequate scientific guidance, necessitating further research to refine fertilization practices. Second, problems such as less-refined culture techniques and lower bait utilization exist during large water surface cultures. Therefore, it is necessary to improve shrimp survival, reduce carbon emissions through refined pond culture management, and optimize feeding strategies and bait structures. Moreover, the recapture rate of shrimp in large surface cultures is currently <30%, which can be improved by adding filter-fed shellfish to shrimp ponds. This approach would not only reduce carbon emissions associated with organic pollutants but also enhance the efficiency of material cycling in aquatic ecosystems and improve water quality, ultimately benefiting shrimp survival rates. Finally, establishing and refining P. vannamei carbon footprint labeling can guide the green consumption market and promote sustainable development of green industries. Consequently, scientific fertilization, precision feeding, and algae-shellfish integrated aquaculture are critical for achieving emission reduction and enhancing carbon sinks in large surface culture systems of P. vannamei. This study supports carbon accounting for P. vannamei pond aquaculture.
