We have heard many times that fishing grounds are being depleted due to the overexploitation of species. It is also widely said that farm fishing could solve this problem. But, are farms the solution to overfishing?
FARM FISHING: THE SOLUTION TO OVERFISHING?
In general terms, the status of wild fish stocks has not improved. By 2013, 58.1% of fish stocks were fully exploited, 10.5% were under-exploited and 31.4% were overexploited (FAO, 2016). Thus, 30% of the populations suffered from overfishing.
This is due to the increasing consumption of fish. According to a report published by FAO, in 2014 each person ate on average about 20 kg of fish, twice as much as in 1960.
On the other hand, since the 1980s, wild catches have remained stable. However, the supply of fish for human consumption has increased considerably. So, if consumption has increased and fishing has remained stable, where does the rest of the fish come from?
The explanation for this fact is in aquaculture: in 2014, catch production was 93.4 million tonnes, while aquaculture production amounted to 73.8 million tonnes. In other words, 44% of the fish came from aquaculture.
Looking at this scenario, it does not seem far-fetched to think that farm fishing could solve the problem of overfishing.
WHY COULD FARM FISHING SOLVE OVERFISHING?
According to the UN World Population Prospects report, by 2050, the world population will have risen to 9.7 billion people.
Given these figures, we can think that the increase in fish consumption will grow well above the production capacity of the oceans and seas. Aquaculture could therefore respond to this increase in the demand of fish for human consumption, in order to meet protein requirements.
Wild populations, therefore, will not be subject to greater pressure than they are now.
Another advantage of fish farms is that production is constant because they have more control over them, that is, there are few fluctuations during the year. This is not true for wild populations, either because of their biological cycle or because they are overexploited.
Finally, farms could reduce the environmental impact caused by fishing: there would be no incidental catches of non-interest species, seabed would not be eroded by trawling…
If you want to know more about aquaculture, I recommend you to watch this video (in this case is about river fishes):
Despite all these advantages, not only are not farms a solution, they also increase the problem of overfishing and cause many other problems.
WHY IS NOT AQUACULTURE A SOLUTION TO OVEREXPLOITATION?
Half of the cultivated species (including both animals and algae) in aquaculture do not require food from outside, because they feed by filtration. Anyway, it is true that this is not the case for carnivorous species.
Without going any further, according to FAO (2016), in 2014, 21 million tons of fish were destined for non-food products, three quarters of which were used to produce fishmeal or fish oil, the main component of feed for carnivorous species of the fish farms.
In other words, to feed fish from fish farms, wild fish have to be caught, which exacerbates the problem of overfishing. According to FAADA, between 3 and 5 tons of wild fish are needed to feed a ton of farm fish.
OTHER PROBLEMS OF FARM FISHING
We have already seen that aquaculture needs to catch wild fish in order to feed the species under cultivation. Now we are going to see other problems for the animals themselves and the environment.
Due to the fact that the cages are installed at fixed points, in the surrounding waters and on the seabed there is a significant accumulation of nutrients and chemicals from feces and uneaten food. This can cause a bloom of algae, which deplete oxygen and, depending on the species, can cause the production of toxic substances.
However, in some cases some measures have been implemented, such as changing the position of cages every year or placing them in areas with strong currents.
The use of antibiotics and vaccines is frequent to prevent or treat diseases as the stress makes them more susceptible. In fact, in the cages the mortality is around 10 to 30%.
Another important problem is that genetically modified fishes are often used. If by accident or by the effect of predators, these organisms escape and mate with their wild relatives, a significant change in the genetic composition of the species can occur (genetic pollution). In fact, between 1992 and 1996, about 1.3 million salmons escaped each year from farms in Norway. Another effect of the leaks is the transmission of diseases and parasites to the wild organisms.
Another disadvantage of farms is that non-native species are often cultivated, that is, species that do not belong to the area in which they are caged. Their escape may involve competition for resources (both food and habitat) with native species. We have already seen that exotic species are a problem for biodiversity.
As we have said, predators can be a problem for companies engaged in fish farming. The solution to this threat is their control or killing, thus affecting their populations.
We have seen that farms have a number of advantages to solving the problem of overfishing. In any case, feeding farmed fish with wild animals further increases the problem of overfishing; in addition to the other existing problems.
What do you think: are the advantages of fish farms more important than their drawbacks? Leave your opinion in the comments of this article.
- FAADA: Piscifactorías
- FAO (2016). El estado mundial de la pesca y la acuicultura 2016. Contribución a la seguridad alimentaria y la nutrición para todos. Roma. 224 pp.
- Overharvest of Fish Population / Aquaculture Industry: Benefits and risks of aquaculture
- Salem State University: Benefits of aquaculture
- TalkingFish.org: All about aquaculture, environmental risks and benefits
- Cover picture: Asc1733 (Creative Commons).