Revealing the unrecognized climate burden of aquaculture systems: A global insight into greenhouse gas emissions and mitigation strategies.

Aquaculture is one of the fastest-growing food production sectors and a significant yet underappreciated source of greenhouse gases (GHGs). Using the most comprehensive aquaculture greenhouse gas dataset to-date and robust modeling, we estimated that aquaculture systems globally emitted 63.90 (19.72 - 103.16) Tg CO2-equivalent per year, with methane being the main contributor. Although aquaculture systems account for <2% of the global lentic habitat area, they contribute 8.8% of the total CH4 emissions from these ecosystems. Per unit area, GHG emissions were lower in coastal systems than inland systems, and shellfish aquaculture had lower emissions than fish and crustacean farming. Geographically, the majority of emissions came from traditionally aquaculture-intensive regions in the mid-low latitudes, particularly East Asia, Southeast Asia, and South Asia. Relative to other major animal products, aquaculture had a lower CO2-eq per unit of protein produced, but its total emissions could still offset 4.0% of the terrestrial carbon sink. Variations in biogeochemical conditions, induced by aeration and nutrient inputs, play a crucial role in regulating GHG emissions from aquaculture systems. Management strategies such as improving aeration, installing bottom lining and optimizing feeding practices would be key to mitigating GHG emissions and lowering the sector's climate impact.