Aquaculture Production is a Large, Spatially Concentrated Source of Nutrients in Chinese Freshwater and Coastal Seas

This paper presents a model-based estimate of nutrient flows in China’s aquaculture system during 2006−2017 using provincial scale data, to spatially distribute nutrient loads with a 0.5° resolution. The results indicate that with the increase in fish and shellfish production from 30 to 47 million tonnes (Mt) during 2006−2017, the nitrogen (N) release increased from 1.0 to 1.6 Mt/year and that of phosphorus (P) from 0.1 to 0.2 Mt/year. Nutrient release from aquaculture was concentrated in a few provinces, contributing >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.

Aquaculture production and associated nutrient excretions are now comparable to those of livestock production systems in China and need to be accounted for when analyzing causes of eutrophication, oxygen depletion and harmful algal blooms and possible mitigation strategies.