This article presents a spatially explicit inventory of nutrient emissions from aquaculture to waterbodies for 2006 and 2017. Aquaculture production and nutrient excretion are now comparable to that of livestock production in China. Nutrient release from fish cultures is an important and spatially concentrated cause of eutrophication and harmful algal blooms.
Aquaculture production in China has been increasing by 50% from 30 to 47 million tonnes per year between 2006 and 2017, and this makes up more than 50% of the global aquaculture production. There is growing concern about eutrophication caused by aquaculture, since nutrients excreted by fish farms are directly released to surface water bodies.
This paper presents a model-based estimate of nutrient flows in China’s aquaculture system using provincial scale data, to spatially distribute nutrient loads with a 0.5-degree resolution. Between 2006 and 2017 the nitrogen (N) release increased from 1.0 to 1.6 Mt yr-1 and that of phosphorus (P) from 0.1 to 0.2 Mt yr-1.
Nutrient release from freshwater aquaculture was concentrated in three provinces (Guangdong, Jiangsu, and Hubei), and that from mariculture in Shandong, Fujian, and Guangdong. Its nutrient release is >20% of total nutrient inputs to freshwater environments in some provinces, and nutrients from mariculture are comparable to river nutrient export to Chinese coastal seas.