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Seafood

Seafood comprises 7% of the protein, and 17% of the animal protein, in the human diet 1 as follows.

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Source: FAOSTAT 2.

Aquaculture and Mariculture

The world is trending toward aquaculture production of seafood, though primarily to augment, rather than replace, wild catch.

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Source: FAO 3.

Aquaculture Potential and Land Use

Farmed fish require protein, which in turn comes in part from wild fish as follows.

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Fish-in-fish-out (FIFO) is the ratio of wild fish into an aquaculture system to fish produced, measured by mass. FIFO is typically higher for carnivorous fish such as salmon, and it has generally been decreasing as aquaculture becomes more efficient and fishmeal is partially replaced by terrestrial feed sources. Source: The Marine Ingredients Organization 4.

A fish-in-fish-out value of 4.9 for farmed salmon has been commonly cited 5, but this value has been rebutted 6.

The move toward aquaculture is motivated in part by limits to what can be sustainably caught in the wild. All of today's wild fisheries could be replaced with aquaculture by using 0.015% of the ocean's surface 7. However, growing feed on land is a greater challenge.

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Source: 8, 9, 10. Tilapia is assessed for Mexico; farmed salmon, chicken, beef, pig and bread land use figures are from European countries; and the rest are worldwide estimates.

Shifting some of the world's diet from terrestrial meat to aquaculture could save land 11, but not as much as shifting to plant-based diets.

Wild Catch Environmental Impacts

Modern fishing uses several types of gear.

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Source: 12. See also Our World in Data 13 for details on the types of gear.

Bottom trawling is of particular ecological concern, as it results in a high rate of bycatch (harvesting of non-target species) and destruction to the seabed floor 14, 15. About 4.9 million square kilometers, or 1.3% of the ocean's area, is trawled each year 16. By disturbing sequestered carbon in the ocean floor, trawling is estimated to release 1.47 billion tons of CO2 each year, a figure comparable to terrestrial farming 16. For all types of fishing, bycatch has been estimate at 40.4% of total catch 17.

Most, and a growing percentage, of fisheries in the world are overfished or fished to their maximum levels.

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Source: FAO 1 with explanatory information from UW 18. 'Overfished' fisheries have less than 80% of the biomass that would give a maximum yield. The share of overfished fisheries has been growing since 1974, and the share of underfished fisheries is declining.

Problem:
Impact of Fishing
Solution:
Eliminate Fishing Subsidies
Problem:
Impact of High-Seas Fishing
Solution:
Eliminate High-Seas Fishing Subsidies
Problem:
Bottom Trawling
Solution:
Ban Bottom Trawling in EU MPAs
Problem:
Impact of Bottom Trawling
Solution:
Ban Bottom Trawling on the High Seas

Illegal, Unreported, and Unregulated (IUU) fishing accounts for an estimated 26 million tons, or up to a fifth of all wild caught fish, worth $23.5 billion 19, with greater rates in low-income countries 20. IUU fishing contributes disproportionately to overfishing, habitat damage, and litter 21, and is associated with other crimes such as arms and drug trafficking and labor abuses 19.

Problem:
IUU Fishing
Solution:
Global Report Requirements

Aquaculture Environmental Impacts

Seafood has the following estimated environmental impacts.

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Source: Gephart et al. 8 via Nature 22.

Following are estimates of greenhouse gas emissions from four methods of seafood production.

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Figures are determined through a literature review of lifecycle assessments. Source: Clark and Tilman 23.

Recirculating aquaculture systems (RAS) are intensive land-based aquaculture ponds, separated from the open ocean. The high impact of RAS is driven primarily by electricity consumption. On other metrics, RAS tends to perform better than other forms of aquaculture due to recycling of nutrients. If electricity is produced from a low-carbon source, RAS may also have lower greenhouse gas emissions.

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Source: d’Orbcastel et al. 24.

Integrated multitrophic aquaculture--or the mixing of species at different levels in the food chain 25--is of interest as a means of conserving feed 6 and reducing overall environmental impacts 26.

Additional environmental impacts of aquaculture include destruction of mangrove forests, water pollution and eutrophication, invasive species, farm and medication waste, and others 27.

References

  1. FAO. "The State of World Fisheries and Aquaculture 2020. Sustainability in action". Rome. 2020. ↩ ↩2

  2. Food and Agriculture Organization of the United Nations. "FAOSTAT". ↩

  3. Food and Agriculture Organization of the United Nations. "Global Aquaculture Production". Accessed January 25, 2020. ↩

  4. The Marine Ingredients Organization. "Fish in: Fish Out (FIFO) ratios for the conversion of wild feed to farmed fish, including salmon". Accessed January 25, 2020. ↩

  5. Tacon, A., Metian, M. "Global overview on the use of fish meal and fish oil in industrially compounded aquafeeds: Trends and future prospects". Aquaculture 285, pp. 146-158. 2008. ↩

  6. Jackson, A. "Fish In - Fish Out (FIFO) Ratios explained". International Fishmeal and Fish Oil Organization. January 2010. ↩ ↩2

  7. Gentry, R. R., Froehlich, H. E., Grimm, D., Kareiva, P., Parke, M., Rust, M., Gaines, S. D., Halpern, H. S. "Mapping the global potential for marine aquaculture". Nature Ecology & Evolution 1, pp. 1317-1324. August 2017. ↩

  8. Gephart, J. A. et al. "Environmental performance of blue foods". Nature ,597(7876), pp. 360-365. September 2021. ↩ ↩2

  9. Guzmán-Luna, P., Gerbens-Leenes, P. W., Vaca-Jiménez, S. D. "The water, energy, and land footprint of tilapia aquaculture in Mexico, a comparison of the footprints of fish and meat". Resources, Conservation and Recycling 165: 105224. February 2021. ↩

  10. Mungkung, R., Gheewala, S. H. "Use of life cycle assessment (LCA) to compare the environmental impacts of aquaculture and agri-food products". In Comparative assessment of the environmental costs of aquaculture and other food production sectors Methods for meaningful comparisons. FAO/WFT Expert Workshop. 24-28 April 2006, Vancouver, Canada. FAO Fisheries Proceedings. No. 10. Rome, FAO. pp. 87–96. 2007. ↩

  11. Froehlich, H., Runge, C., Gentry, R., Gaines, S., Halpern, B. "Comparative terrestrial feed and land use of an aquaculture-dominant world". Proceedings of the National Academy of Sciences of the United States of America 115(20), pp. 5295-5300. May 2018. ↩

  12. Zeller, D., Pauly, D. "Sea Around Us: Fisheries, Ecosystems & Biodiversity". University of British Columbia. Accessed October 20, 2021. ↩

  13. Ritchie, H., Roser, M. "Fish and Overfishing". Our World in Data. October 2021. ↩

  14. Pusceddu, A., Bianchelli, S., Martín, J., Puig, P., Palanques, A., Masqué, P., Danovaro, R. "Chronic and intensive bottom trawling impairs deep-sea biodiversity and ecosystem functioning". Proceedings of the National Academy of Sciences of the United States of America 111(24), pp. 8861-8866. May 2014. ↩

  15. Victorero, L., Watling, L., Deng Palomares, M. L., Nouvian, C. "Out of Sight, But Within Reach: A Global History of Bottom-Trawled Deep-Sea Fisheries From >400 m Depth". Frontiers in Marine Science 5(98). March 2018. ↩

  16. Sala, E. et al. "Protecting the global ocean for biodiversity, food and climate". Nature 592(7854), pp. 397-402. April 2021. ↩ ↩2

  17. Davies, R. W. D., Cripps, S. J., Nickson, A., Porter, G. "Defining and estimating global marine fisheries bycatch". Marine Policy 33(4), pp. 661-672. July 2009. ↩

  18. Sustainable Fisheries. "How many fisheries are overfished, and what does that mean?". University of Washington. Accessed October 20, 2021. ↩

  19. Janovsky, J. "Up to 1 in 5 Fish Sold Is Caught Illegally—and Other Surprising Illegal Fishing Facts". Pew Charitable Trusts. November 2017. ↩ ↩2

  20. Agnew, D. J., Pearce, J., Pramod, G., Peatman, T., Watson, R., Beddington, J. R., Pitcher, T. J. "Estimating the Worldwide Extent of Illegal Fishing". PLOS One 4(2): e4570. February 2009. ↩

  21. Food and Agriculture Organization of the United Nations. "Four reasons illegal, unreported and unregulated (IUU) fishing affects us and what we can do about it". April 2021. ↩

  22. Nature. "Blue food". 2021. ↩

  23. Clark, M., Tilman, D. "Comparative analysis of environmental impacts of agricultural production systems, agricultural input efficiency, and food choice". Environmental Research Letters 12(6). June 2017. ↩

  24. d’Orbcastel, E., Blancheton, J., Aubin, J. "Towards environmentally sustainable aquaculture: Comparison between two trout farming systems using Life Cycle Assessment". Aquacultural Engineering 40(3), pp. 113-119. May 2009. ↩

  25. Martinez-Porchas, M., Martinez-Cordova, L. "World Aquaculture: Environmental Impacts and Troubleshooting Alternatives". The Scientific World Journal. Article ID 389623, 9 pages. 2012. ↩

  26. Prescott, S. "Exploring the Sustainability of Open-Water Marine, Integrated Multi-Trophic Aquaculture, Using Life-Cycle Assessment". University of Stirling, Aquaculture eTheses. October 2017. ↩

  27. Martinez-Porchas, M., Martinez-Cordova, L. R. "World Aquaculture: Environmental Impacts and Troubleshooting Alternatives". The Scientific World Journal. January 2012. ↩