More crucially, while the use of antibiotics in aquaculture remains the same as their livestock counterpart, the dosage administered in the former can be much higher proportionally compared to the latter (O’Neill, 2015). This, combined with the fact that antibiotics can remain within the aquatic environment for an extended period of time—there is evidence to suggest that 70 to 80% of antibiotics fed to fish are excreted into the water (Cabello et al., 2013; Burridge et al., 2010)—has led to experts dubbing aquaculture sites as “reservoirs” and “hotspots” for AMR genes (Van et al., 2020; Watts et al., 2017; Muziasari et al., 2016).
The situation is further aggravated by the rapidly growing practice of aquaculture itself—since the stress of industrial-scale farming compromises the fish’s immune system, it justifies the widespread use of antibiotics as a way to compensate for the fish’s increased vulnerability to infections and diseases (Meek, Vyas, and Piddock, 2015). A recent study between CIRAD and French National Research Institute for Development has also shown global warming may even promote the use of antibiotics, particularly in the low- and middle-income countries—warmer temperatures almost always result in higher mortality rates of fish, which could lead to an increased use of antibiotics (Reverter et al., 2020).
Unsurprisingly, the development of AMR in aquaculture production (as with any other agri-food industries where antibiotics are used) adversely has devastating affects on the environment and public health, typically in the form of superbugs, i.e. bacteria that should have been killed by antibiotics, but instead evolved to become stronger. Yet, overall data on the amount of antibiotics used in aquaculture and how much of it is absorbed into the aquatic surroundings is still far from satisfactory. Approximately 90% of global aquaculture production is carried out in countries where regulations on antimicrobial use are either lax or non-existent, resulting in data that varies greatly from nation to nation (Watts et al., 2017).