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The Issues with Aquaculture

Lauren Pinder - Teen Aspect - June 12th, 2022
Fish Farm in Skjerjehamn, Norway. Photo taken by Seregey Ponomarev.

What is aquaculture? Aquaculture is the industry that breeds, raises and harvests aquatic species such as fish, shellfish and plants in the ocean.

While the worldwide amount of wild-caught seafood has remained consistent over the years, the amount raised through aquaculture has risen dramatically. “The United States imports 70 to 85 percent of its seafood, and nearly 50 percent of this imported seafood is produced via aquaculture.”[2] Additionally, driven by imports, the U.S. seafood trade deficit has grown to “$16.9 billion in 2019.”[2]

Aquaculture allows for commercial and recreational fisheries to be supported, and it can be used as a tool to restore habitats and species. The United States is a minor aquaculture producer but a major player in global aquaculture, as it is the leading global importer of fish and fishery products.

In the United States, marine aquaculture production increased an average of 1.7 percent per year from 2013 to 2018.” In the same time frame, sales of domestic marine aquaculture increased an average of 1.5 percent per year. [2] Through aquaculture, the United States supplies a variety of advanced technology, feed, equipment and investment capital to other producers across the globe.

The use of aquaculture has caused a rapid turnover of wildly caught to widely grown seafood available for purchase. For instance, since the 1960s salmon farming has grown so large that 70% of the world’s salmon production is from ocean farming. In the U.S. 90% of sold salmon were farmed.[3]

While Aquaculture is an established industry in world trade, there are various sustainability issues associated with it that pose a threat to the ocean and marine life. Seawater pollution from fish farm waste and increased concentrations of pesticides and pharmaceuticals found in the ocean disrupt the natural nutrient concentrations that make up the natural balance of ecosystem homeostasis, the balance of organisms in an environment.

Furthermore, a rise in diseased farmed fish populations, increased use of chemical controls, resistance to chemical compounds amongst pests such as sea lice, and a rise in genetically engineered species and the spread of their DNA into wild populations negatively affects the wild populations of fish and other marine organisms who do not have resistance or tolerance to disease and chemicals present in fish pens.

The majority of these issues occur due the “escapes” of farmed fish from pen damage, predators, or harsh local conditions. Escaped fish swim into the open ocean and begin to mingle with natural populations.

The crossbreeding of genetically engineered salmon, for instance, weaken the wild population’s genetics. Farm-grown salmon are modified to mature earlier and grow faster than wild salmon populations, and a crossbreed of wild and genetically modified genes could undermine the wild population’s ability to survive and reproduce in a natural habitat.

The fish pens that house farmed fish reside in open sea lochs, or branches of the sea that are narrow and or partially landlocked. Fish that live in pens grow in an environment with an extremely high concentration of surrounding fish, a concentration that is not normal for wild salmon populations. Farmed fish are fed laced food covered in pharmaceuticals and the residues of pesticides to limit pest infestations and outbreaks of disease.

The food and fecal matter build up forms tons of waste that dissolves into the surrounding sea, rich with large concentrations of nitrate. When nitrate is combined with phosphorus, an element present in agriculture run off and industrial discharges, the process of eutrophication is accelerated.Increased Eutrophication as a result of the practices performed in sea lochs where fish are grown affect the local marine environments, leading to dramatic increases in plant growth that destabilizes marine ecosystems by affecting what type of marine life resides in that ecosystem, which will then alter temperature, pH, and dissolved oxygen levels in the sea.

Eutrophication leads to the rapid growth of algal blooms that cover the surface of the water and smother all other residing marine life by creating a hypoxic habitat, or a habitat lacking oxygen, due to the algaes’ consumption of oxygen present in the water and blocking of sunlight from aquatic plants that typically produce oxygen via photosynthesis. With a lack of oxygen other organisms will either die or relocate, destroying an established complex food web.

Not only does overwhelming amounts of nitrate affect marine life but also humans who swim in open water. Nitrate affects how humans carry oxygen in the blood by turning the protein hemoglobin; a protein that carries oxygen, into methemoglobin; a protein that does not bind with oxygen and cannot deliver oxygen to tissues. Toxic doses of nitrate range from 2-5 grams while lethal concentrations range from 4-50 grams. High levels of nitrate can turn the skin blue or gray, can cause more severe health complications such as fatigue, weakness, dizziness, excessive heart rate, thyroid disease and risks of developing certain kinds of cancer.[4] Nitrate toxicosis occurs when methemoglobin concentration is at 30-40%, and death occurs when the methemoglobin concentration reaches 80-90%.

Humans also face potential consumption of toxic chemicals by the ingestion of seafood. If fish farms use antibiotics on fish, this can pose an issue of resistant bacteria in both fish and humans. Also, the fungicides and other chemical pesticides used to tamper diseases amongst grown fish populations are not commonly tested for when importing fish into other countries. Imported salmon may contain the fungicide malachite green which is considered to be carcinogenic in animals.[5] Though we may not think so, humans are a part of the food chain. Fish such as salmon are larger fish and accumulate pollutants in their tissues by the constant consumption of smaller fish through bioaccumulation or chemicalized feed to satisfy their diet. When humans consume the fish, they consume the pollutants too.

While the dangers of antibiotic, pesticide and chemical use is harmful to humans, pets and agriculture crops is widely known, the consequences of aquaculture confirm the notion that too much of a good thing becomes a bad thing.

Fish farms will not disappear, as fish is a resource-friendlier food alternative to beef for feeding increasing world populations; however, sustainable aquaculture practices are being developed to limit the environmental impact aquaculture curates. Moving fish farms indoors improves efficiency as well as ocean contamination, and alternatives to fish feed are solutions that provide the possibility of a reduced toll on the environment and health of humans and marine species.

Works Cited:

[1] Ponomarev, S. (n.d.). photograph, Skjerjehamn, Norway.

[2] Fisheries, N. O. A. A. (2021, July 8). U.S. aquaculture. NOAA.

[3] Beyond Pesticides. (2022, May 19). Pesticides, Pharmaceuticals Used in Industrial Fish Farms Threaten Swimmers, Marine Life. The Defender.

[4] Bureau of Environmental and Occupational Health. (2019, December). High levels of nitrate in drinking water can affect everyone. Wisconsin Department of Health Services.

[5] Wallentine, C. (2017, August 29). The problem with farmed fish - their food is spreading antibiotic resistance. WonderHowTo.

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