Aquaculture Doesn’t Solve ‘Overfishing’ — It Relies On It

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The consumption of aquatic animals is a neglected issue compared to the consumption of land animals or the protection of companion animals. Yet it poses major ethical problems since aquatic animals are fully capable of experiencing pleasure and suffering, and are caught and killed by the billions each year; the most recent estimate made by Fish Count is between 790 billion to 2.3 trillion annually. Overfishing poses other major problems such as the degradation of marine ecosystems, the extinction of aquatic species, and the endangerment of human populations that depend on fishing. There are several solutions to overfishing, and aquaculture is often proposed as one of them. 

This report from the Aquatic Life Institute focused on one of the problems of aquatic animal farming: “blue loss”. Blue loss refers to the number of aquatic animals that aren’t accounted for in the human food chain. They are used to produce human food, but are not directly consumed by humans. Some can be used as fertilizer or to feed land animals, but most of them are used as food for other fish such as salmon. For example, this report indicated that a salmon needs the biomass of nine herring or 120 anchovies to reach their harvest weight. 

To estimate blue loss, the authors determined the different categories in which these fish could appear. For each category, they estimated the number of individuals involved. Unfortunately, the data on fish are not in numbers of individuals, but in tons. Therefore, in order to estimate the number of individuals in each category, they also needed to determine the different species caught, their proportions, and their weights. With this information, it was possible to estimate the number of fishes, and the sum of all the fishes in each category gives us the total blue loss. 

To do all of this, they used the most recent data from the Food and Agriculture Organization of the United Nations (FAO), from 2018. They also relied on independent studies for additional data or information. 

Here are the different categories involved in the blue loss calculation, with the estimated number of individuals in each one: 

• Fishes explicitly caught for processing into oil or fish meal, 662 billion. 
• By-products of human consumption used as fish feed, 38 billion. 
• Fishes caught, killed but discarded at sea, 96 billion. 
• Fishes used as live food, 487.6 billion. 

These estimates are made as best as possible with the available data and studies. And the reality could be different since the data is initially in tons and only based on legal fishing. However, it gives us a good idea of the order of magnitude and the extent of the problem. For those who want to have more details on the methodology and calculations used, these are very well communicated in the report. 

Put together, the number of fishes caught each year, but not accounted for in the human food chain, is about 1.2 trillion. Compared to the Fish Count’s estimate, this number represents half of the fishes caught, and most of them end up feeding other fishes. This shows that aquaculture is currently not a solution to overfishing, as it relies essentially on fishing to feed the animals raised. 

When someone eats a fish, especially a carnivorous species like salmon or trout, they’re not just eating one dead animal, they’re indirectly eating all the animals previously eaten by that one fish to grow — and there could be a hundred more. Sadly, all these fishes share the same ability to experience pleasure and suffering. This is important information that most consumers probably don’t know.

To reduce the blue loss, the authors pointed out that insects could be used to feed fish — but given the average weight of an insect, it would require several quadrillions of them (that’s a 1 with 15 zero after it) to equal the weight of fish currently used. Even if insects are less conscious, this could lead to much more suffering. Thus, it is not a good idea to replace fishing with insect farming. 

Another solution considered by the authors is the development of a plant-based fish feed. They believe this is one of the best solutions. One possible action for individuals and organizations would be to invest in this direction in order to create one with the same qualities as the current one. Such an alternative could replace the fish caught and save billions of lives.