Aquaculture – Sustainable Food, Unsustainable behaviors
What is Aquaculture?
With the increase in global middle-class, the demand for seafood has increased. As such, with the huge stresses placed on wild-fish stocks, aquaculture has begun to increase in popularity. Aquaculture is the process of producing food and other products in water environments. As such, reducing the stress placed on traditional wild-life fishing (Global Aquaculture Alliances,2019).
Although aquaculture seems like a great idea, producing food while reducing stress on wildlife stocks, many of these aquaculture developments are often unregulated. As such, problems with pollution due to aquaculture is becoming a more prevalent issue. Pollution from aquaculture stems from two major sources, firstly being the nutrients derived from fish food and waste and secondly, from the chemical pollution from the treatment of fishes and ponds (White et al., 2017).
We will take a look at these forms of pollution in two different settings in which aquaculture takes the form.
Pollution of Land-based Aquaculture
Land-based Aquaculture focuses on creating ponds and lakes, in order to grow common aquacultures such as shrimps and flounders. As such, land-based aquaculture has to prepare the optimal settings for aquaculture to grow, through the use of chemical treatment of the ponds. This can include the salinization of the ponds to grow salt-water varieties such as shrimps, which in terms leads to soil pollution as the soil below becomes oversaturated with salt (Cao et al., 2007). Often, these ponds will be emptied after the conditions become unconducive for aquaculture, which leaves behind land parcels that are unsuitable for agriculture.
Also, land-based aquaculture is much more severely affected by nutrients discharge compared to ocean aquaculture. This is where the use of fish feed as well as the discharge of fish waste causes an imbalance of nutrients in the system. The decomposition of fish feed and fish wastes contributes nitrates and phosphates which in turn creates the problem of eutrophication, especially when the pond becomes unmanaged (White et al., 2017). Therefore, the original problem of soil destruction can eventually lead to large scale environmental impacts at other locations, especially when these nutrient-rich water is discharged.
Pollution of Ocean Aquaculture
On the other hand, Ocean Aquaculture involves the use of cages in open-sea water, with the rearing of aquaculture occurring in shallow waters, usually near bays and brackish water. With the nature of design, many of these aquaculture pens cause problems due to the introduction of nutrients directly into the ocean. As ocean aquaculture tends to be floating platforms, many of these fish wastes fall under the cage, onto the seafloor. As such, these accumulated wastes serve to pollute the seabed and cause harm to the biological growth of wild fish (Bergland et al., 2020)).
Furthermore, another problem with ocean aquaculture is the introduction of chemical pollution, especially in the form of antibiotics pollution. When antibiotics are mixed in with fish feeds, the uneaten fish feed can lead to the decomposition of these antibiotics, which in turn leads to a buildup of bacteria immunity against antibiotics. Furthermore, fishes can ingest these bacteria, which can become a health hazard when fishes are caught and eaten by people (White et al., 2017). Thus, this bio-accumulation of bacteria and parasites in aquaculture with immunity against antibiotics can eventually lead to large-scale contaminations, especially in the ocean, where water flows freely, potentially bringing these bacteria into other parts of the oceans.
Conclusion
All in all, aquaculture seeks to reduce the strain we are putting on the fishing of wildlife. However, we need to consider the impacts on environmental pollution that aquaculture brings, especially on pollutants such as nutrients and antibiotics. Moreover, we need to determine which forms of aquaculture are the best either in-land or sea-based aquaculture. The main difference in nutrient-led eutrophication is that sea-based aquaculture tends to rely on currents to reduce the chances of algae bloom due to eutrophication. However, if the water used for in-land aquaculture is treated before release, the chances of eutrophication can also be decreased. All in all, we must look for alternatives within aquaculture to reduce the impact of aquaculture on our environment. After all, aquaculture is the right step forward to sustainable food farming.
In the next post, we shall take a look at a potential solution to aquaculture, which will reduce the impacts of pollution.
Detective Out,
Wen Hong
References
Bergland, H., Burlakov, E., Pedersen, P. A., & Wyller, J. (2020). Aquaculture, pollution, and fishery – dynamics of marine industrial interactions. Ecological Complexity, 43, 100853. https://doi.org/10.1016/j.ecocom.2020.100853
Global Aquaculture Alliances. (2019, March 27). What is aquaculture, and why do we need it? Global Aquaculture Alliance. https://www.aquaculturealliance.org/blog/what-is-aquaculture-why-do-we-need-it/
National Ocean Services. (2019, November). What is Aquaculture? https://oceanservice.noaa.gov/facts/aquaculture.html#:~:text=Aquaculture%20is%20breeding%2C%20raising%2C%20and,of%20threatened%20or%20endangered%20species
Singh, M. (2014, June 6). Can farmed fish feed the world without destroying the environment? NPR.org. https://www.npr.org/sections/thesalt/2014/06/06/319247280/can-farmed-fish-feed-the-world-without-destroying-the-environment
White, P., Cassou, E., Soto, D., & Beveridge, M. (2017). Aquaculture Pollution. An Overview of Issues with a Focus on China, Vietnam, and the Philippines. https://openknowledge.worldbank.org/bitstream/handle/10986/29249/122927-WP-P153343-PUBLIC-Aquaculture-working-paper.pdf?sequence=1&isAllowed=y
World Bank Regional Agricultural Pollution Study
