By Nichos Molnar, Winter 2021.
Humans have utilized agriculture since the beginning of organized civilization. Agriculture has been with us for so long that innovations and advancements in the field aren’t interesting to most people. However, aquaculture – even in the name itself – is mysterious and novel enough that it can capture people’s attention. Aquaculture describes a diverse range of diverse range practices and methods that all spring from the same general principle: the domestication and farming of terrestrial species can be reproduced in an aquatic environment. As a practice, aquaculture isn’t young, with some of the earliest accounts dating back to 500 BC China [1]. Still, most associate the words “Ocean” and “Food” with fishing or trawling activities, reflecting the belief that the only way to obtain fish is to hunt wild populations. While natural fisheries still play a large role in the seafood industry, more than half of all the seafood consumed by humans is farmed.
Aquaculture enjoys some distinct advantages over more traditional forms of farming and fishing. Fish farmers have much finer control over their harvested populations than traditional fishermen, reducing the risk of overfishing and the collapse of fishing stocks. Because farmed fish are not supposed to interact with the surrounding environment harvesting them does not negatively impact the food supply of the surrounding waters.
In addition, aquaculturists are taking advantage of modern genomics techniques to optimize the domestication of a diverse range of fish species. Farmed fish can be artificially selected for traits that help improve their growth rate, size, and disease resistance. Farmed fish are also bred for higher nutritional value: strains of farmed salmon have a higher fatty acid concentration than wild strains, providing health benefits for consumers [2]. Alongside these benefits, marine species are easier to domesticate than land species due to their relatively quick generation times and large reproductive output [3]. Each of these benefits of aquaculture demonstrates the huge potential for marine species domestication; furthering domestication could vastly improve efficiency and sustainability, providing food security for millions of people worldwide. Aquaculture also enjoys the benefits of species diversity: while 80% of worldwide meat production comes from three animal species (chickens, pigs, and cows), more than 70 species of fish supply 80% of global aquaculture production [4]. Aquaculture is a rapidly growing industry that represents new horizons for food and nutrition.
Despite the great benefits agriculture promises, the finer (and often negative) details of aquaculture are easily overlooked. Just as land-based agriculture has obvious disruptive and destructive effects on the ecosystem and environment it takes over; aquaculture is similarly tied to its environment, albeit on a less visible scale. While deforesting land for agricultural use provides a stark example of exactly how the pre-existing environment is disrupted, the effects of introducing a plot of nets into a river delta are much harder to see. One of the most prevalent examples of environmental disruption from aquaculture is the farming of Atlantic Salmon (Salmo Samar), which often occurs in places where wild populations of Salmo salar are depleted. Aquaculture nets aren’t perfect, and farmed salmon often escape into the environment and join the already weakened wild salmon population. The worldwide farmed salmon population dwarfs the wild population – even by 1995, approximately 94% of adult Atlantic Salmon were in aquaculture [5]. Even if escape events are relatively uncommon, farmed salmon escapees and their hybrid progeny comprise even larger proportions of wild populations. Often, the interbreeding between the wild and farmed salmon creates offspring with reduced chances of survival and breeding [6]. The continual flow of escapees from aquaculture sites weakens the gene pool of wild populations, reducing their ability to survive and adapt to changing conditions like those caused by climate change. While the effects of escapees and the fitness of hybrid fish varies by species and location, they are almost always negative for the wild populations.
Farmed fish are also susceptible to disease. The high density of fish in an enclosed area, combined with poorer water quality and circulation, creates ideal breeding grounds for several types of diseases and parasites that usually don’t pose as high of a threat. The parasites and diseases present in the farmed fish populations can spread quickly among farms, and even to wild populations. Furunculosis – a disease with high mortality in salmon – was introduced to Norway from Scotland after a transfer of fish and infected 70% of Norwegian farms and several rivers within three years [7]. Despite this, the idea that diseases can exist in a marine environment is foreign to most people, even consumers. There is no fish equivalent to swine or bird flu. Unfortunately, disease treatment can be just as harmful to the environment as the disease themselves, as the use of antibiotics or other treatments can introduce harmful chemicals into the marine environment. Aquaculturists need to be highly cognizant of their effects on the environment, as anything they introduce into their nets will rapidly spread into the surrounding water.
Despite these negative effects, aquaculture is an important part of the global economy, especially in the developing countries where 90% of all aquaculture takes place [8]. Aquaculture provides an important source of food security and income for developing countries, especially those with pre-existing aquacultural traditions like India or Indonesia. It diversifies nutritional intake, improves its home countries’ self-sustainability, and creates economic growth and job opportunities. In the end, aquaculture is more sustainable than most commonly used fishing methods and will alleviate pressure on wild fisheries. Environmental and ecological impacts can be mitigated by creating stronger pens and using genetic tools to prevent interbreeding between farmed and wild populations. Aquaculture is still in its growth phase: we can learn from its issues and guide it down a path towards a sustainable and environmentally friendly source of food and growth for the entire planet.
(1) Allen, P. J. & Steeby, J. A. 2012. “Aquaculture: Challenges and Promise.” Nature Education 3 (Summer): 12
(2) Foran, Jeffery A. et al. 2005. “Quantitative Analysis of the Benefits and Risks of Consuming Farmed and Wild Salmon.” The Journal of Nutrition 135, no 11, (November): 2639–2643. https://doi.org/10.1093/jn/135.11.2639
(3) Duarte, Carlos M., Marbá, Nùria, and Holmer, Marianne. 2007. “Rapid Domestication of Marine Species.” Science 20, no. 316 (April): 382-383. https://doi.org/10.1126/science.1138042
(4) Anderson, James L. et al. 2017. “Aquaculture: Its Role in the Future of Food.” Frontiers of Economics and Globalization, Vol. 17: 159-173. https://doi.org/10.1108/S1574-871520170000017011
(5) Gross, M. R. 1998. “One species with two biologies: Atlantic salmon (Salmo salar) in the wild and in aquaculture.” Canadian Journal of Fisheries and Aquatic Sciences 55, no S1. https://doi.org/10.1139/d98-024
(6) Skaala, O. et al. 2012. “Performance of farmed, hybrid, and wild Atlantic salmon (Salmo salar) families in a natural river environment.” Canadian Journal of Fisheries and Aquatic Sciences 69 (November):1994–2006. https://doi.org/10.1139/f2012-118
(7) Naylor, R. et al. 2005. “Fugitive Salmon: Assessing the Risks of Escaped Fish from Net-Pen Aquaculture.” BioScience 55, no 5 (May): 427–437. https://doi.org/10.1641/0006-3568(2005)055[0427:FSATRO]2.0.CO;2