Environmental Implications of an Increasing Dependence on Farmed Fish 

Serena Chen (‘19)
Lawrenceville

In 2012, half of the fish that humans consumed came from farms. In China, this amount reached as high as 80%. By 2030, the United Nations Food and Agriculture Organization (UNFAO) reports that aquaculture will be responsible for almost two-thirds of total fish consumed. What explains this trend toward more farm-raised fish, and what impacts does the practice have on our environment?

According to Michael Barange, the U.N. FAO’s fisheries director, said that “In the struggle to make sure we have enough food to feed more than 9 billion people in 2050, any source of nutrients and micronutrients is welcome.”

UNFAO reports that 31% of the world’s fish populations are overfished, and another 58% are fished at the maximum sustainable level. At the rate fish are taken from the oceans, fish will not be able to reproduce quickly enough to feed the world’s human population. Thus, people have increasingly turned to fish farming.

Global aquaculture farming methods range from earthen ponds to high-tech tank systems, and include over 100 species of fish. In bag-and-rack shellfish cultures, juvenile shellfish are raised in bags suspended by racks above the seabed. The juveniles come from hatcheries, so wild populations will not be depleted. The shellfish filter-feed, making wild fish-feed unnecessary. Thus, the bag-and-rack method is generally considered an environmentally responsible system of aquaculture.

Fish farming may be a viable solution to solving the issue of a decreasing amount of resources with an increasing human population. However, fish farming methods must be reassessed to ensure that the benefits of producing more fish are not counteracted by the farms’ harms to the environment.

Open net-pens and cages enclose fish in offshore coastal areas or in freshwater lakes. Likewise, ponds enclose fish such as catfish and tilapia in coastal or inland bodies of fresh or saltwater. While wastewater can be contained and treated, the waste can pollute surrounding areas and defile groundwater. The fish freely expel waste into the open waters, polluting the surrounding area with concentrated excretions, which may carry diseases and parasites, to surrounding wild fish populations. These and other fish farms produce high-levels of pollution as fish manure fertilizes surrounding algae, reducing the amount of oxygen available to other fish species, leading to dead zones. In fact, Scotland’s salmon farming industry alone produces an amount of waste equivalent to the untreated sewage of 3.2 million people. The fish can also escape and compete with wild fish for resources and interbreed.

Recirculating systems house fish such as salmon, striped bass, and sturgeon in tanks in which water is recycled and treated. The system solves the issues of water contamination and fish escaping but is costly to maintain and relies on electricity and other energy sources. 

While many other types of fish farming techniques exist, each has its own specific environmental footprint. Fish farming may be a viable solution to solving the issue of a decreasing amount of resources with an increasing human population. However, fish farming methods must be reassessed to ensure that the benefits of producing more fish are not counteracted by the farms’ harms to the environment. 

Sources:
(1) Gaia Vince. “How the World’s Oceans Could Be Running Out of Fish.” BBC, 21 September 2012, http://www.bbc.com/future/story/20120920-are-we-running-out-of-fish.

(2) Renee Cho. “Making Fish Farming More Sustainable.” State of the Planet, 13 April 2016. Earth Institute, Columbia University, http://blogs.ei.columbia.edu/2016/04/13/making-fish-farming-more-sustainable/.

(3) “Global fish production approaching sustainable limit, UN warns.” The Guardian, https://www.theguardian.com/environment/2016/jul/07/global-fish-production-approaching-sustainable-limit-un-warns.

(4) Ayana Elizabeth Johnson, Jennifer Jacquet. “Will the Ocean Ever Run Out of Fish?” National Geographic, 11 August 11 2017, https://blog.nationalgeographic.org/2017/08/11/will-the-ocean-ever-run-out-of-fish/.

(5) “Farmed Salmon vs. Wild Salmon.” Washington State Department of Health, https://www.doh.wa.gov/CommunityandEnvironment/Food/Fish/FarmedSalmon.