Something’s fishy about fish farming

Over the years, the increasing human population has resulted in a higher demand for food—including fish. Under these circumstances, traditional methods of fishing involving spears and harpoons gradually transitioned to more modern methods such as fish farming. Fish farming is the practice of raising fish in a net cage, pen, or enclosed system. Over the years, many producers have adopted this practice due to its convenience, efficiency, and profitability. This practice will assuredly continue to expand as the human population continues to rise. Even now, fish farming provides a practical and effective source of food for the 7.3 billion and more people on the earth. However, these practices come at a cost: namely, the degradation of the environment and the economy.

First of all, the establishment of fish farms requires immense modifications to the surrounding ecosystem. Fish farming involves raising fish in enclosed systems. Some of these systems include rice fields, cages, ponds, pens, raceways, tanks, and recirculating systems—all of which are different approaches to fish farming but all use up sizable amounts of land.

In addition, fish farming introduces another drastic change to the ecosystem through “pumping large volumes of underground water to achieve brackish water salinity” (Cao, 2007). This practice causes a wide array of issues such as “lowering of groundwater levels, emptying aquifers, land subsidence and salinization of adjacent land and waterways” (Cao, 2007). Some of this salinization affects “adjoining rice and other agricultural lands” (Cao, 2007). Once the soil is affected by salinization, it makes the land unsuitable for agriculture. These are spaces that humans depend on, where they produce crops and raise livestock  As such, fish farming endangers other equally vital food production systems.

Fig. 1: Collapsed net pen used by Cooke Aquaculture Pacific

Second of all, fish farms pollute. They accumulate solid waste that comprises mainly of feces and uneaten fish feed. Once decomposed, this waste releases nitrogen and phosphorus into the surrounding area. This can lead to eutrophication—an excess concentration of nutrients in a body of water.  Eutrophication causes a plethora of issues to the environment such as “energy and nutrient fluxes, pelagic and benthic biomass and community structure, fish stocks, sedimentation, nutrient cycling, and oxygen depletion” (Cao, 2007). Aside from feces and uneaten fish feed, chemicals and antibiotics also contribute to pollution in fish farms. Fish living in these contaminated enclosures experience an increased “risk of infectious diseases and deteriorating groundwater and other local ecosystems, for instance after flooding” (Cao, 2007).

In Scotland, reports have demonstrated that “45 lochs had been badly polluted by the antibiotics and pesticides used to control lice—and that more and more toxic chemicals were being used” (Vidal, 2017). In the event of other foodstuffs, contaminated water from fish farms will pollute nearby water resources—including freshwater resources used for drinking and irrigation. Without floods, contaminated still reaches “natural coastal waters if directly discharged” (Ottinger, 2016). As waste accumulates in fish pens, a solution adopted by fish farms is to dispense the waste into other nearby water resources.

Lastly, decreasing biodiversity is another reason that justifies why fish farming is an unviable solution to feeding the human population. The main source of food for fish consist of fish meal and fish oil. In 2003, an approximate “5.2 million metric tons of fish meal were used for purposes other than human consumption” (Diana, 2009). However, fish meal is a limited resource as it is derived from small pelagic species of fish. Combined with the amount of fish meal used for intensive livestock feeding and the pet food industry, fish meal is being consumed at an exceedingly fast pace. This overexploitation of fish meal will eventually lead to a decline in biodiversity as more pelagic species of fish are caught and made into fish meal. A decline in the population of small pelagic fish species will affect other species whose diets are reliant on these small fish species for food.

Fig 2: Within the 5.2 million metric tons of fish meal used in 2003, over 46% of fish meal and 81% of fish oil are used towards aquaculture (Diana, 2009).

There is no denying the incredible potential fish farming has on feeding an increasing human population. However, fish farming also poses a dangerous threat to the environment and the species that inhabit that environment. As such, new procedures and inventions must be developed–ones that possess the potential of fish farming while not posing a threat to the environment. In fact, such procedures and inventions are in the making. It is just a matter of time that they be put to use.



Cao L., Wang W., et al. (2007): Environmental Impact of Aquaculture and Countermeasures to

Aquaculture Pollution in China. Environmental Science and Pollution Research International, 14(7), 452–462.

Cummings, Vivien (2016, Mar. 14). How Many People Can Our Planet Support. Retrieved

November 17, 2018, from

Diana, J. S. (2009). Aquaculture Production and Biodiversity Conservation. Bioscience, 59(1),


Flatt, Courtney, and John Ryan (2018, Apr. 24). ‘Environmental Nightmare’ After Thousands of

Atlantic Salmon Escape Fish Farm. Retrieved November 17, 2018, from

Ottinger, M., et al. (2016). Aquaculture: Relevance, Impacts and Spatial Assessments—A

Review. Ocean and Coastal Management, 117, 244-266.

Vidal, J. (2017, April 01). Salmon Farming in Crisis: ‘We are Seeing a Chemical Arms Race in

the Seas’. Retrieved November 16, 2018, from 2017/apr/01/is-farming-salmon-bad-for-the-environment

Shawn Tran

Shawn is a second-year student with an intended major in Public Health and a minor in Chinese. He is a native of Sacramento – the city of trees and capital of California. His interests include hiking, traveling, spending time with family, and learning different languages and cultures. Through joining SERC Blog, he hopes to bring awareness to important environmental issues and topics. Shawn Tran covers aquaculture and environmental economics.

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