The steadily increase in consumer demand for seafood and the concurrent depletion of many wild fish stocks, aquaculture, or “fish-farming,” is now used to produce almost half of the world’s seafood.1 In fact, aquaculture is currently the fastest growing sector of global food production; as wild fisheries continue to be overexploited and mismanaged, aquaculture production is expected to double by 2050.2
Unfortunately, the industrialization of aquaculture has resulted in many of the same environmental and human health problems currently created by livestock factory farms. As in the case of industrial livestock production, many of the harmful impacts of industrial aquaculture stem from the concentration of large numbers of animals within small facilities. In addition to polluting aquatic ecosystems with the enormous volume of waste produced by the fish they confine, aquaculture facilities threaten the environment and human health by releasing hazardous substances such as pesticides, antibiotics, and other drugs into the aquatic environment. Industrial aquaculture operations can also harm natural fish populations by introducing diseases and non-native species into the ocean.
Pollutants Emitted by Aquaculture Facilities
Open water industrial aquaculture facilities typically confine fish within cages or netpens, which allow fish waste, uneaten feed, chemicals, pharmaceuticals, and other pollutants to pass directly into the surrounding water.
As in the case of livestock manure, when large quantities of fish feces enter an aquatic ecosystem, nutrient levels in the water increase. As described in the Environmental Impacts section, the influx of excess nutrients induces algal growth, and can ultimately lead to eutrophication and the reduction of aquatic biodiversity.3
The constant release of uneaten feed causes similar problems; when feed accumulates on the seafloor, it is eventually decomposed by bacteria, which consume oxygen dissolved in the water and can thus create hypoxic “dead zones” below aquaculture facilities.4 The environmental damage caused by fish feces and uneaten feed is particularly severe in enclosed waters with low water exchange rates (ex. lakes, slow-moving rivers, and shallow bays).
Pesticides and Pharmaceuticals.
In attempt to prevent disease and epidemics of parasites, industrial aquaculture operations use large quantities of drugs, pesticides, and other chemicals. Although the environmental and human health impacts of many of these substances are not well understood, their use is poorly regulated, reporting requirements are insufficient, and federal oversight is inadequate.5 While some chemicals threaten consumers’ health by leaving harmful residues in fish, drugs and pesticides can also wreak havoc on the environment since many are toxic to aquatic plants and animals.6,7 For more information, read Food & Water Watch’s detailed analysis,
Misuse of Antibiotics
When thousands of fish are confined in a small space, it’s easy for disease to spread quickly. Often, industrial aquaculture facilities address this problem by utilizing the same irresponsible antibiotics practices as industrial livestock operations; rather than reducing the density of fish, fish farms continuously administer subtherapeutic doses of antibiotics. This promotes the proliferation of antibiotic-resistant bacteria, which can infect humans.8 The problem is exacerbated by cages and netpens allowing antibiotics and antibiotic-resistant bacteria to pass freely into surrounding waters.
Escapees and Biodiversity
Aquaculture facilities also threaten natural ecosystems by facilitating the introduction of nonnative marine species (or domesticated varieties of native species) into the surrounding environment. As a result of net damage from storms, industrial accidents, and attempts by marine mammals to catch farmed fish, many aquaculture facilities release substantial numbers of fish into the environment. For instance, the David Suzuki Foundation estimates that in British Columbia, an average of 90,000 farmed salmon escaped each year between 1990 and 2000.9
Fish that escape from aquaculture facilities pose a significant threat to the viability of existing wild populations – particularly to sensitive populations that have already suffered from overfishing or habitat loss. While nonnative fish species threaten native populations by competing for food and habitat, farmed varieties of native species also pose an environmental threat; after having escaped from pens, farmed fish may breed with their wild counterparts, thereby introducing farmed genetic traits into the gene pool of wild populations. This can dramatically reduce the genetic diversity of the given species in a short period of time.10
Parasites and Disease
Despite intensive use of antibiotics and pesticides, crowded conditions within aquaculture facilities foster the proliferation of parasites and disease, which can spread to wild marine species.11 The large number of fish within industrial aquaculture farms provides ample hosts for parasites such as sea lice; epidemics can decimate farmed fish, and also affect wild populations – especially when aquaculture facilities are situated along migratory routes of wild fish.12
Aquaculture facilities can also introduce viral and bacterial diseases into wild fish populations – disease can be spread by live fish that escape from pens, contaminated equipment, fish parts, sea lice, and humans who handle contaminated fish.13 The risk of disease transmission is increased when imported, unprocessed fish are used as feed. For instance, imported pilchards fed to tuna farmed in Australia are thought to have caused viral outbreaks in 1995 and 1998 that killed 75 percent of the wild adult pilchard population in South Australia.14
Depletion of Wild Fish Stocks
Some aquaculture facilities use massive quantities of wild fish, which are processed to create feed for carnivorous fish species such as salmon, trout, tuna, cod, and grouper. For instance, experts estimate that 2.7 to 3.5 pounds of wild fish are used to produce one pound of farmed salmon;15 as many as 20 pounds of wild fish are consumed to produce a pound of tuna.16 This resource-intensive form of production depletes the stock of small fish such as anchovy, sardine, pilchard, and mackerel, which can ultimately disrupt aquatic ecosystems by adversely affecting predators such as large fish, marine mammals, and seabirds.17 Researchers are looking for ways to minimize the use of wild fish in feed, but not all the alternatives are positive. Soy is increasingly used to add protein to fish feed; a practice which could encourage the industrial production of mono-cropping genetically engineered soy.
Fortunately for seafood lovers, certain forms of aquaculture can be conducted without creating ecological disaster. Re-circulating land-based farming operations are able to raise fish in closed systems without emitting pollutants into the surrounding environment; many of these fish farms refrain from using antibiotics, hormones, or chemicals. Small-scale aquaponic operations raise fish and vegetables/herbs in the same system, using the plants to filter out waste and use it as fertilizer. Sustainable aquaculture facilities can also choose to raise omnivorous or herbivorous fish species such as catfish, tilapia, or carp to minimize (or even eliminate) the use of wild fish in feed. In conjunction, sustainable aquaculture and better management of wild fisheries can provide us with long-term access to seafood.
Did You Know?
In 2002, more than 630,000 salmon escaped from aquaculture facilities in Norway – that’s more than the total number of Atlantic salmon that spawned naturally in Norway’s rivers!18
In 2005, 51,953 Atlantic Salmon Escapes from a Sites in Scotland treated with Slice/Emamectin Benzoate 22
15 to 20 percent of all feed can pass into surrounding waters uneaten, thus creating a substantial stream of waste.19
Currently, Asia is the world leader in aquaculture, representing over 90 percent of total tonnage, while North America produces only 1.6 percent.20
More than 80 percent of the seafood consumed in the United States is imported, and the U.S. exports about 70 percent of what is caught or farmed here into countries with higher import standards than are maintained in the U.S.2121
For More Information:
Food & Water Watch Fish Program (www.foodandwaterwatch.org/fish)
Information relating to open ocean aquaculture, seafood safety, oceans management and sustainable solutions for aquaculture.
Aquaculture Network Information Center (ANIC)
Created by the USDA Extension Service, this site provides access to an extensive selection of national and international electronic aquaculture resources.
SeaWeb Aquaculture Resources
A comprehensive collection of regularly updated aquaculture resources from SeaWeb, a nonprofit organization that works to promote ocean conservation.
U.S. Food and Drug Administration Center for Veterinary Medicine – CVM and Aquaculture
The FDA is responsible for overseeing the use of drugs administered to fish within aquaculture facilities. This site includes the Guidance documents, sections of the Policy and Procedures Manual, research projects, and other information used in support of CVM’s aquaculture program, as well as drugs approved for use in aquaculture.
Consumer Guides to Buying Seafood:
Provides guidelines for choosing clean, green, safe seafoods. Includes a printable seafood substitutes card for sustainable alternatives to popular seafood choices, a cookbook with sustainable seafood recipes, and detailed information on why various types of seafood are or are not good choices for consumers.
Food and Water Watch
Basic guidelines for purchasing safe, sustainably raised fish. Also includes a printable restaurant card, which can be used to request that your favorite restaurant switch to wild-caught seafood.
Food and Agriculture Organization of the United Nations. The Role of Aquaculture in Sustainable Development. FAO September 2007. Medical News Today, “Sustainable Aquaculture Critical to Feed the World,” Feb 21, 2007. Scottish Association for Marine Science and Napier University. Review and Synthesis of the Environmental Impacts of Aquaculture. Scottish Executive Central Research Unit. 2002. Weber, Michael L. What Price Farmed Fish: a review of the environmental & social costs of farming carnivorous fish. SeaWeb Aquaculture Clearinghouse. 2003. Food & Water Watch. Yuck! Harmful Aquaculture Chemicals and Waste. Food & Water Watch. May 2008. U.S. Food and Drug Administration. Fish and Fisheries Hazards and Controls Guidance: Third Edition. Accessed June 2008. Weber, Michael L. What Price Farmed Fish: a review of the environmental & social costs of farming carnivorous fish. SeaWeb Aquaculture Clearinghouse. 2003. Cabello, Felipe C. “Heavy use of prophylactic antibiotics in aquaculture: a growing problem for human and animal health and for the environment.” Environmental Microbiology. Vol. 8, 7. July 2006. The David Suzuki Foundation. Escaping Farmed Salmon Pose Risks. 2007.
10. Weber, Michael L. What Price Farmed Fish: a review of the environmental & social costs of farming carnivorous fish. SeaWeb Aquaculture Clearinghouse. 2003.
11. Scottish Association for Marine Science and Napier University. Review and Synthesis of the Environmental Impacts of Aquaculture. Scottish Executive Central Research Unit. 2002.
12. Weber, Michael L. What Price Farmed Fish: a review of the environmental & social costs of farming carnivorous fish. SeaWeb Aquaculture Clearinghouse. 2003.
13. Weber, Michael L. What Price Farmed Fish: a review of the environmental & social costs of farming carnivorous fish. SeaWeb Aquaculture Clearinghouse. 2003.
14. WWF, the World Conservation Organization. Aquaculture Problems: parasites and disease. 2008.
15. David Suzuki Foundation. Net Loss of Wild Fish to Produce Farmed Salmon. Accessed June 2008.
16. SeaWeb Aquaculture Resources. Aquaculture Feeds. Accessed June 2008.
17. SeaWeb Aquaculture Resources. Aquaculture Feeds. Accessed June 2008.
18. WWF, the World Conservation Organization. Aquaculture Problems: Exotic Escapees. 2008.
19. Weber, Michael L. What Price Farmed Fish: a review of the environmental & social costs of farming carnivorous fish. SeaWeb Aquaculture Clearinghouse. 2003.
20. FAO, “Regional Review on Aquaculture Development/ 7. North America – 2005.” 2005.
21. Calculations conducted by Food & Water Watch based on data from: “Fisheries of the United States 2007.” Office of Science and Technology, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Silver Spring, MD, July 2008. For methodologies, please contact firstname.lastname@example.org
Please note that statistics listed here are based on 2007 data, which is the most current available in synthesized form from the NOAA Fisheries Office of Science and Technology. The most up-to-ate statistics on U.S. aquaculture production, which are included in these calculations, are taken from the USDA 2006 census.
22. Summary of self-reported data on open cage net-fish farming Companies in Scotland (Raw Data Provided By Scottish Environment Protection Agency (SEPA) and Scottish Executive)