Writer: Ezgi Cakirgoz
Aquaculture, the controlled cultivation of aquatic organisms, emerged as a response to the increasing global demand for seafood and the depletion of fish stocks. The practice of aquaculture dates back thousands of years, but its modern form has gained prominence due to the growing population, changing dietary preferences, and concerns about overfishing. As traditional fishing methods became unsustainable and failed to meet the rising demand for seafood, aquaculture provided a viable solution.
It is not uncommon to see humans trying to fix the ecosystem they have destroyed. Like any industry, aquaculture comes with its own set of drawbacks and challenges concerning the environment. As always in ecology, this impact on the environment also has serious harm to our health (Cole et al., 2009).
Effects on the Environment
One of the major drawbacks of unsustainable aquaculture is the excessive use of antibiotics and chemicals. To prevent and control diseases in densely populated aquaculture facilities, farmers often resort to the indiscriminate use of antibiotics. This practice can lead to the development of antibiotic-resistant bacteria. This practice can lead to the development of antibiotic-resistant bacteria, posing risks not only to the aquaculture industry but also to human health. Additionally, the runoff of chemicals and antibiotics from aquaculture operations can contaminate nearby water bodies, further impacting aquatic ecosystems. For example, in some shrimp farms, farmers have been known to use antibiotics such as chloramphenicol and nitrofurans to control diseases. These substances can have detrimental effects on non-target organisms and persist in the environment (Boyd & Massaut, 1999).
Some practices can result in the escape of farmed species into natural ecosystems, leading to genetic pollution. Escaped farmed fish can interbreed with wild populations, compromising the genetic integrity of native species. This can weaken the resilience of wild populations, making them more susceptible to diseases and environmental changes. In the Atlantic salmon farming industry, escape incidents have been reported, raising concerns about the potential genetic impact on wild salmon populations (Burridge et al., 2010).
Aquaculture can place excessive demands on natural resources, contributing to habitat degradation and over-extraction of water. Some aquaculture systems, such as certain types of intensive shrimp farms, require the clearing of large areas of mangroves and the extraction of vast amounts of water, further exacerbating environmental impacts. Intensive shrimp farming in some regions has been associated with the destruction of mangrove forests, affecting the diverse ecosystems and fisheries that depend on these habitats (Naylor et al., 2009).
Many operations are located in coastal areas, where mangroves and other critical ecosystems are often cleared to make way for fish farms. The destruction of these habitats not only diminishes biodiversity but also reduces the natural buffering capacity of coastal ecosystems, making them more vulnerable to extreme weather events and rising sea levels. The expansion of shrimp farming in Southeast Asia has been linked to extensive mangrove deforestation, leading to the loss of vital habitats for numerous species and disrupting the balance of coastal ecosystems (Chua Thia Eng et al., 1989).
(A Cambodian woman carries baskets of fish at the Tonle Sap River bank in Phnom Penh Photo: Mak Remissa - EPA-EFE)
Effects on the Human Health
As mentioned before, unsustainable aquaculture often involves the use of chemicals and pesticides to control parasites and diseases in densely populated fish farms. These substances can accumulate in the tissues of farmed fish, posing a direct threat to human health when consumed. Heavy metals, such as mercury, and persistent organic pollutants can contaminate the flesh of farmed fish, leading to long-term health risks, including neurotoxicity and developmental issues. Farmed salmon, a popular choice in many markets, has been found to contain higher levels of contaminants, including polychlorinated biphenyls (PCBs) and dioxins, compared to wild-caught salmon.
The use of antibiotics in aquaculture to prevent and treat diseases in crowded conditions contributes to the development of antibiotic-resistant bacteria. When consumers ingest seafood containing antibiotic residues, it can compromise the effectiveness of antibiotics in treating human infections. The rise of antibiotic resistance is a significant global health concern, and the overuse of antibiotics in aquaculture is a contributing factor. Shrimp farms, in particular, have been known to use antibiotics like oxytetracycline and sulfa drugs, leading to concerns about the presence of antibiotic residues in farmed shrimp.
Aquaculture facilities, especially those with poor biosecurity measures, can become breeding grounds for various pathogens. Some of these pathogens are zoonotic, meaning they can be transmitted from animals to humans. Inadequate sanitation and proximity between farmed species create conditions conducive to the spread of diseases that can pose a direct threat to human health. Vibrio bacteria, which can cause illnesses ranging from mild gastroenteritis to severe infections, have been linked to the consumption of contaminated seafood, including farmed shrimp.
Feed used in aquaculture often contains allergenic ingredients, and some farmed species may be exposed to allergens during their cultivation. Consumers with allergies to certain substances, such as soy or shellfish, may unknowingly consume allergens present in farmed seafood, leading to allergic reactions. As an example, if fish feed contains soy protein, individuals allergic to soy may experience adverse reactions after consuming farmed fish that have been exposed to soy-based feed (Sapkota et al., 2008).
(Skretting: East Africa is aquaculture's next big frontier - IntraFish)
What should be done?
As the aquaculture industry continues to evolve to meet the world's demand for seafood, it is essential to prioritize practices that safeguard both environmental and human health. Sustainable aquaculture methods, such as responsible farming practices, reduced use of chemicals and antibiotics, and improved biosecurity measures, can mitigate the risks associated with the consumption of farmed seafood. By raising awareness about the potential drawbacks of unsustainable aquaculture on human health, consumers, policymakers, and industry stakeholders can collectively contribute to the development of a healthier and more sustainable seafood industry.
References
Cole, D. W., Cole, R., Gaydos, S. J., Gray, J., Hyland, G., Jacques, M. L., Powell-Dunford, N., Sawhney, C., & Au, W. W. (2009, July). Aquaculture: Environmental, toxicological, and health issues. International Journal of Hygiene and Environmental Health, 212(4), 369–377.
Boyd, C. E., & Massaut, L. (1999, June). Risks associated with the use of chemicals in pond aquaculture. Aquacultural Engineering, 20(2), 113–132.
Burridge, L., Weis, J. S., Cabello, F., Pizarro, J., & Bostick, K. (2010, August). Chemical use in salmon aquaculture: A review of current practices and possible environmental effects. Aquaculture, 306(1–4), 7–23.
Naylor, R. L., Hardy, R. W., Bureau, D. P., Chiu, A., Elliott, M., Farrell, A. P., Forster, I., Gatlin, D. M., Goldburg, R. J., Hua, K., & Nichols, P. D. (2009, September 8). Feeding aquaculture in an era of finite resources. Proceedings of the National Academy of Sciences, 106(36), 15103–15110.
Chua Thia Eng, Paw, J. N., & Guarin, F. Y. (1989, July). The environmental impact of aquaculture and the effects of pollution on coastal aquaculture development in Southeast Asia. Marine Pollution Bulletin, 20(7), 335–343.
Sapkota, A., Sapkota, A. R., Kucharski, M., Burke, J., McKenzie, S., Walker, P., & Lawrence, R. (2008, November). Aquaculture practices and potential human health risks: Current knowledge and future priorities. Environment International, 34(8), 1215–1226.