Who will be caught in the net? An unsung story on the ecological impact of fishing and aquaculture
A fish does not campaign against fisheries - it only tries to slip through the mesh.
- Aleksandr Solzhenitsyn
Note for the reader: you may interact with each data visualization!
Around the world, 8 people out of 10 are interested in reducing their environmental footprint. However, not everyone is aware that we can personally help in the fight against climate change. We can contribute with something we constantly deal with and on which we consciously act every day: food. Indeed, it is estimated that food production is responsible for a quarter of the world’s greenhouse gas emissions [1].
A common piece of advice, to reduce our footprints, is to eat locally. Actually, this may be a bit of misleading advice since transportation has only a marginal impact on the food environmental footprint. Some examples are reported in the image below [1].
It would be more accurate to consider the entire food chain and choose what we have for lunch taking into account each food’s impact. Reasoning this way and comparing the various foods, it emerges that drastic actions are needed in order to effectively contribute to climate change.
First of all, it would be necessary to considerably reduce the consumption of beef and sheep meat, cheese, chocolate and coffee.
So: less meat, less cheese, not into vegetables… let’s have fish every day! Actually, not so fast. The situation is more complex than it appears. The purpose of this article is to bring to light a topic that is often kept silent: the environmental impact of fishing and aquaculture.
Fish consumption has increased over the years and it is predicted to increase even more in the future decades. So, it would be better to analyze the environmental impact and take action before things get out of control.
Let’s dive in!
Fishing
Without sound conservation and management measures, fisheries will quickly become depleted and a basic component of global food security will be lost.
- Sigmar Gabriel
From 2012 to 2019 the number of fishing vessels has increased dramatically to match the increasing demand for fish commodities and consumption.
The fishing vessels reported in the map below are only a part of the problem: many vessels are not reported to institutions and illegal fishing is one of the major issues [3].
Thus the data we have is just a lower bound to the real problem; the real truth is that many vessels manage to escape controls.
Fishing vessels behave pretty much like cars: they need gasoline to power their engines and they are responsible for CO₂ emissions in the atmosphere.
CO₂ emissions have been computed multiplying the engine power of each vessel by the number of hours spent fishing [5].
This estimate does not take into account the CO₂ emissions produced by vessels to reach the fishing spot or to go back to the port.
China alone in 2020 has been responsible for over 5,000,000 metric tons CO₂, which is the equivalent of an Airbus A380 full load traveling to Venus.
According to public opinion, the fish environmental footprint is due only to greenhouse gas emissions related to its supply chain. Actually, it would be necessary to take into consideration other factors, which play a role in ruining the marine ecosystem.
First of all, the multiple gear types used for wild catch and farmed fishing should be considered. Have you ever thought that in order to be able to eat salmon on Sundays, corals, algae and other ‘useless’ fishes for our tables have also been taken from the marine ecosystem?
More or less sustainable fishing methods are exploited all over the world: the Marine Conservation Society (MSC), a UK charity fighting for a cleaner, better-protected and healthier ocean, classified the fishes according to their sustainability level, from 1 (best choice) to 5 (fish to avoid).
The main fact to point out is that less sustainable fishes are wild-caught using the gear type called bottom trawl.
Compared to what it has been said above, let’s dig into the most harmful technique: bottom trawl.
This is an industrial fishing method exploiting huge nets weighed down by heavy ballast: they are dragged along the seafloor, in an effort to catch fish, “raking up or crushing everything in their way, from fish to ancient coral” [8].
Many species, including those at risk of extinction, are accidentally caught and then thrown back into the sea, often already dead. These collateral losses, known as discards, can reach up to 80% or even 90% of the total catch [9].
If you want to know more about gear types, click here.
Aquaculture
Aquaculture is another determining aspect to consider when talking about fish. Its employees’ number nearly tripled in the last 25 years, going from around 7 million people in 1995 to 20 million in 2018, reaching half the employees of fisheries [10].
Despite what one might think and what papers say [11], aquaculture is as dangerous as fisheries are. Possibly aided by the fact that it is easier to track, it is responsible for emitting a number of greenhouse gases that is 30% higher than that produced by fisheries [11, 12].
If you take a Tesla and drive it around the world 60 million times, you would produce the same amount of greenhouse gases as aquaculture does in just one year. Crazy, right? [13]
If you were wondering, this is not the end of the story. Around one-fifth of the fish coming from fisheries is employed for feeding aquaculture fishes [14]. That fish, accounting for around 97 million tonnes of greenhouse gas emissions [15], makes aquaculture GHG emissions jump to 340 million tonnes every year.
Summing up, taking into account the ratio between total emissions and employees, aquaculture has on average 4 times the emissions per employee of fisheries.
Conclusions
Even though we reported just some of the main issues, we reached a greater awareness about the fish environmental footprint. To wrap up, we analyzed:
- CO₂ emissions by the monitored fishery engines;
- how different gear types have a huge impact on the marine ecosystem;
- consequences of aquaculture.
Moreover, a lack of data characterizes the whole subject. Indeed, we weren’t able to find open data about overfishing tracking or estimates about the actual damage to the ecosystem brought by any gear type. Furthermore, many regions in Africa and Asia still don’t keep track of their fisheries despite the FAO effort [3].
So, nowadays it is still difficult to have a complete picture of the fishing footprint, but we hope this article made a step towards the comprehension of the problem.
To the naked eye, our oceans are beautiful. But scientists tell us that all of the world’s fisheries will collapse by 2048, unless we change how we manage them. Help protect our oceans so the next generation can also enjoy their bounty.
- Ted Danson
Bonus: next time you go to the supermarket, we’ve got you covered: follow the figure below for choosing what fish to buy!
Authors
Matteo Ferrini - linkedin.com/in/matteo-ferrini/
Virginia Migliorini - linkedin.com/in/virginia-migliorini-2b92b1182/
Mattia Surricchio - linkedin.com/in/mattiasurricchio/
Carlo A. Vitellio - linkedin.com/in/carlo-vitellio/
References
[1] Hannah Ritchie and Max Roser (2020) — “Environmental impacts of food production”. Published online at OurWorldInData.org. Retrieved from: ‘https://ourworldindata.org/environmental-impacts-of-food
[2] OECD/FAO (2021), “OECD-FAO Agricultural Outlook (Edition 2020)”, OECD Agriculture Statistics (database) — https://doi.org/10.1787/4919645f-en (accessed on 23 May 2021).
[3] Sustainable fisheries — How many fisheries are overfished, and what does that mean? — https://sustainablefisheries-uw.org/fact-check/how-many-fisheries-are-overfished/
[4] Global Fishing Watch — https://globalfishingwatch.org/data-download/datasets/public-fishing-effort
[5] Environment Protection Agency — https://www.epa.gov/energy/greenhouse-gases-equivalencies-calculator-calculations-and-references
[6] Our World in Data — https://ourworldindata.org/travel-carbon-footprint
[7] MSCUK — https://www.mcsuk.org/goodfishguide/
[8] Overfishing, why is it so important? — https://intergratedscienceoverfishingcom.wordpress.com/2016/02/01/destructive-fishing-practices-and-bycatch/
[9] FAO — Fishing Gear type http://www.fao.org/fishery/geartype/search/en
[10] FAO — http://www.fao.org/3/ca9229en/ca9229en.pdf#page=53
[11] MacLeod, M.J., Hasan, M.R., Robb, D.H.F. et al. Quantifying greenhouse gas emissions from global aquaculture. Sci Rep 10, 11679 (2020). https://doi.org/10.1038/s41598-020-68231-8
[12] Parker, R.W.R., Blanchard, J.L., Gardner, C. et al. Fuel use and greenhouse gas emissions of world fisheries. Nature Clim Change 8, 333–337 (2018). https://doi.org/10.1038/s41558-018-0117-x
[13] Electrive.com — https://www.electrive.com/2020/08/31/study-currently-available-electric-cars-cause-less-co2-emissions-than-ices/
[14] Guillen, J., Natale, F., Carvalho, N. et al. Global seafood consumption footprint. Ambio 48, 111–122 (2019). https://doi.org/10.1007/s13280-018-1060-9
[15] Scarborough, P., Appleby, P.N., Mizdrak, A. et al. Dietary greenhouse gas emissions of meat-eaters, fish-eaters, vegetarians and vegans in the UK. Climatic Change 125, 179–192 (2014). https://doi.org/10.1007/s10584-014-1169-1
