Can Aquacultures Feed the World without Collapsing the Marine Food Chain?


If you are craving fish, you might decide to buy it from a fish market, a nearby store, or maybe go eat at a fancy restaurant. No matter how you get the fish or what type you will have on your plate, it will be sourced in one of two ways: capture or aquaculture.

Capture is the old way: fishermen head to places where the fish are and catch them! This method has improved over time with the advancement in technology, which has allowed for capturing more in less time with much less manpower. Fishing is still the dominant way to get fish to our plates; yet, the numbers suggest that it is not the future of fishing.

According to the Food and Agriculture Organization (FAO) of the United Nations (UN), for the past fifty years, the amount of caught fish has been almost the same, but the total amount of fish produced has been increasing. This increase has been accounted for by aquacultures, which have also given a higher value produce. Aquaculture is a method to farm aquatic life, such as fish, in a controlled environment; they can be cages of fresh or saltwater, on land or in the open ocean.

In an aquaculture, instead of allowing fish to grow on their own, they are taken care of. This implies monitoring fish reproduction, making sure they are well-fed, and keeping them healthy through vaccination and medications, as well as getting rid of their faeces. This is not an easy task, since fish excrete five times more than humans (relative to their weight), and need a lot of protein-rich food. The most common source of food for aquaculture is smaller fish, which is not consumed by humans.

From all the fish caught from the oceans, one-third is small fish, which is used as food for the farmed fish. UN estimates the amount of small fish we can capture from the ocean without hurting the food chain by 30 million tons annually. It also estimates that, by 2030, if we keep the current rates, we will reach that number. This problem is intensifying as aquacultures get more popular. Farmed fish types, such as salmon, are usually in high demand. For every kilogram of salmon, up to 15 kilograms of small fish are caught, pressed into fish meal, and used to feed them.

On the other hand, aquacultures are more sustainable with other species. Species lower in the food chain, such as clams and oysters, are usually non-fed aquacultures; meaning they require no feeding and depend solely on food sources found in the water, such as aquatic plants. Some species are even beneficial for the environment when farmed in aquacultures, such as sea cucumbers, which can even help get rid of wastes of other species' aquacultures!

Aquacultures could play a major role in our food supply. If managed responsibly, they can be a sustainable source of food for the world.



Can aquaculture overcome its sustainability challenges?

The European Commission's science and knowledge service

The State of World Fisheries and Aquaculture 2020

The Story of More: How We Got to Climate Change and Where to Go from Here - Hope Jahren


Top image: Salmon Aquaculture in Norway. Credit: Wikimedia Commons.

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