In this guide, we outline the pros and cons of aquaculture and fish farming.
We focus mainly on the farming of fish, crustaceans and bivalves in both land based and ocean based farming operations.
Summary – Pros & Cons Of Aquaculture & Fish Farming
Overall, aquaculture and fish farming has been used in some capacity for 1000’s of years
However, production from fish farming has significantly increased over the last few decades to the point it matches or outpaces some forms of wild caught fishing and also land based conventional agriculture
Fish farming and aquaculture can be a potential alternative method of food production to conventional agriculture to provide nutrients and protein to a growing human population
Various advances and developments are helping to improve fish farming in several ways, whereas in the past there may have ben some clear problems environmentally and from a sustainability with fish farming
Some methods of fish farming may also be considered a more sustainable form of fishing, and may provide some of the benefits that sustainable fishing practices can provide
The pros and cons of fish farming are nuanced, and depend on several variables such as the type of fish farmed, where they are farmed, how they are farmed, the type of feed used (especially the % of fish meal, fish oil, and vegetarian ingredients used in the feed), the breeding rate of the fish, and the resources used (such as water, electricity, and more)
Continuing to focus on how aquaculture and fish farming can be economically competitive and profitable, can be able to scale to meet demand, whilst also considering the welfare of the fish being farmed and what practices might be sustainable, might be some areas of focus in the future
A summarised list of potential pros and cons of aquaculture and fish farming:
Pros
There are some clear solutions to past problems with aquaculture and fish farming i.e. practices have become more sustainable and eco friendly over time
Aquaculture has controllable factors that impact the environment and sustainability
Problems with pond based aquaculture specifically can be managed with proper site selection, proper management of soil and water quality [and proper management of the fish culture]
Some farmed fish can be raised on vegetarian meal/feed, trimmings and processing outputs (making feed more sustainable or circular)
Is one way to increase the food supply/food production for the future human population
Farmed fish production is already significant compared to beef and other meats
The future outlook for aquaculture in terms of demand looks favorable according to several assessments
Aquaculture shows potential to improve across several areas in the future, in terms of production, technological advances, and sustainability
Conversion efficiency can be high compared to other types of meat
Aquaculture may have a lower emissions footprint than ruminant animals
Might have a higher chance of being free of environmental contaminants like mercury compared to wild caught fish
In some cases, aquaculture can increase water quality
Aquaculture can be profitable as a business
Can be used as a form of small business in lesser developed regions
Fish waste can sometimes be used for crop fertilization
Specific types of farmed fish may have small ecological and sustainability footprints
There can be other miscellaneous sustainability and environmental benefits of aquaculture
Cons
Good management may not prevent technical difficulties with aquaculture
There can be practical problems with pond based aquaculture
Some farmed fish need wild fish as feed, and it can be resource inefficient when considering feed to production conversion, or place pressure on wild fisheries
The resource footprint of aquaculture can vary
There’s potential waste and waste pollution to consider with fish farming
Fish farming can use forage fish species, which can undermine marine food webs
Can result in disease, abandonment habitat destruction
Disease transfer from farmed fish to wild fish is a potential problem
Farmed fish escaping into the wild environment might be problematic
The economics and profitability of fish farming has faced issues in some countries and fish farming industries
There can be a conflict of interest between production at scale, meeting demand, running at profit and the wlefare of the fish
Some slaughter methods are can be considered to be inhumane
Land based salmon may have sustainability problems when scaling to meet higher demand
*Note – this is a general guide only.
Obviously the real pros and cons of fish farming and aquaculture depend on the fish (or water organism) being farmed, how they are farmed, the processes used, and other variables specific to an individual fish farming operation in a specific area.
What Is Aquaculture and Fish Farming?
The nature.com resource listed does a good job of outlining what aquaculture and fish farming is.
To paraphrase:
– It can involve the production of aquatic organisms, which includes fish, mollusks, crustaceans, algae and plants
– There’s a number of strategies that are used, and the different systems come under the category of either extensive or intensive production
– Under the extensive or intensive production banner, there’s earthen ponds, raceways, cages, net pens, and recirculating systems
– Farming systems can be created, or placed into exiting ocean or land based water bodies
Per treehugger.com: It can involve freshwater or saltwater fish, plants, or other life forms, and the reasons might be commercial … or they might be environmental or research-based
What Are The Most Farmed Fish In The World?
Per wikipedia.org: ‘Worldwide, the most important fish species produced in fish farming are carp, tilapia, salmon, and catfish’
Where Do Most Farmed Fish Come From?
Per wikipedia.org: ‘China provides 62% of the world’s farmed fish’
Pros Of Aquaculture & Fish Farming
There are some clear solutions to past environmental and sustainability problems with aquaculture and fish farming
[In the past, some types of fish farming and aquaculture may have had some clear problems, but] new strategies and technologies have emerged and have proven that it is possible to have sustainable aquaculture.
[Siting fish farms in waters with strong currents, paying attention to the density of fish in an area, recognising the potential benefits of land based aquaculture on ecosystems over aquaculture farmed in natural water sources like the ocean where environmental problems can be more prevalent, declining antibiotic use, and using cameras and inspecting enclosures for escape points – can all decrease the environmental and sustainability impact of fish farming]
– aquaculturealliance.org
… pollution from coastal salmon farms [was a problem in the past, but] these days even salmon farms are producing 10 to 15 times the fish they did in the 1980s and 1990s with a fraction of the pollution … (nationalgeographic.com)
Aquaculture has controllable factors that impact the environment and sustainability
Controllable factors mean that the environmental impact and impact on sustainability can be controlled too.
[Ultimately, environmental and sustainability based impact can be nuanced]
… the environmental impact of aquaculture is completely dependent upon the species being farmed, the intensity of production and the location of the farm [and these factors are controllable by the producer]
– aquaculturealliance.org
Problems with pond based aquaculture specifically can be managed with proper site selection, proper management of soil and water quality [and proper management of the fish culture]
[This can contribute to] growing healthy fish, achieving satisfactory production and improving culture efficiency [as well as] high yield and profit (researchgate.net)
Some farmed fish can be raised on vegetarian meal/feed, trimmings and processing outputs
Vegetarian fish meal and feed may be more sustainable and eco friendly in several ways compared to other types of feed.
There’s also the animal welfare side of feed to consider if other fish and aquatic life are used as feed.
But, some vegetarian meals and feeds may only be part vegetarian, and part meat based.
Obviously if wild caught fish are used as feed, this places more pressure on open ocean and open water fisheries to sustainable fish farming and aquaculture for production
Trimmings and leftovers from processing might be other forms of more sustainable feed that can go to fish
… some aquaculture species are raised on vegetarian feed [which can come in the form of meals and oils] (earthjournalism.net)
From aquaculturealliance.org:
Sustainable fish feeds are on the rise
Fishmeal and fish oil used in feeds may come from trimmings from processing plants.
Additionally, substituting plant proteins for fishmeal in feeds is also becoming more prevalent
Is one option to increase the food supply for the human population in the future
Fish farming/aquaculture is one food production method that can help feed the population in the future, along with other options such as conventional agriculture, sustainable agriculture, lab grown food, and other food production methods and technology
[Aquaculture is] a subsistence provider of protein for human populations …
… Developing and developed nations will both benefit from an increased realization of the potential for aquaculture, as well as the need for protein derived from aquaculture in the face of continuing population growth
– nature.com
From aquaculturealliance.org: Fish farming, when done sustainably, can be the answer to filling the gap in seafood supply that stressed fisheries are creating.
Farmed fish production is already significant compared to beef and other meats
The world now produces more farmed fish than beef [and amounts] to nearly half of all fish and shellfish consumed on Earth
Aquaculture has expanded about 14-fold since 1980
– nationalgeographic.com
The future outlook in terms of demand for aquaculture looks favorable according to some assessments
Increasing human populations combined with limited natural resources in freshwater and the world’s oceans, which are currently near maximum harvest yields … mean that the demand for seafood must be met by aquaculture (nature.com)
This resource efficient protein can fill the gap in supply to meet the demand of the world’s growing population.
The tools are now available to assist farms in developing sustainably, and it is up to farmers to take advantage of them
– aquaculturealliance.org
Population growth, income growth, and seafood’s heart-healthy reputation are expected to drive up demand by 35 percent or more in just the next 20 years.
With the global catch of wild fish stagnant, experts say virtually all of that new seafood will have to be farmed
– nationalgeographic.com
Aquaculture shows potential to improve in the future across several aspects of it’s production
[Potential to improve might come from] recirculating systems and aquaponic systems [which could help deliver] a fresher and more environmentally friendly product, with less fossil fuels and expense in transport, packaging and storage, as well as the appeal of a locally-grown product. … [and] … marine aquaculture, offshore areas offer great potential for culturing species due to a lack of space restrictions, good water quality, and the ability to culture species that are in great demand (nature.com)
Conversion efficiency for fish farming and aquaculture can be high compared to other types of meat
Compared to beef, pork and chicken specifically, when assessing feed to protein conversion rates.
Farmed seafood is incredibly resource efficient, especially when compared with other animal proteins (beef, pork, chicken).
The feed conversion ratio, which is the measurement of how much feed it takes to produce the protein, is 1.1.
This means that essentially one pound of feed produces one pound of the protein.
Beef, pork and chicken’s feed conversion ratios vary between 2.2-10.
As a result, seafood’s protein retention, as well as energy retention are remarkably high as well.
– aquaculturealliance.org
[Of all the farmed organisms, fish might have the best feed conversion efficiency for several reasons to do with requiring less energy]
[Aquaculture involves] the efficient growth of fish … [and several key factors lead] to energy savings, which provides more available energy for growth, resulting in the highest feed conversion efficiency of widely domesticated animals
– nature.com
The nationalgeographic.com resource listed has a graphic showing the conversion efficiency of different meats
Read more about the sustainability of different meats in this guide
Aquaculture may have a lower emissions footprint than ruminant animals
Might have a higher chance of being free of environmental contaminants like mercury compared to wild caught fish
Farmed fish are generally free of environmental contaminants like mercury and heavy metals, as they exclusively eat human-processed feed.
Fish feed’s toxin levels are [also] regulated
– aquaculturealliance.org
In some cases, aquaculture can increase water quality
[Like for example where] filter-feeders, like shellfish [are farmed] (aquaculturealliance.org)
Aquaculture can be profitable as a business
[Aquaculture is a profitable business, but this can depend on key goals such as] maximizing growth rate and minimizing production costs [though] (nature.com)
Can be used as a form of small business in lesser developed regions
[For example, some families can use small ponds to farm species like fresh water prawns] (nationalgeographic.com)
Fish waste from fish farming can sometimes be used for crop fertilization
Providing health and safety standards are met and abided by, this could contribute to a more circular economy.
[There is an example in Bangladesh of fish waste being used to fertilizer rice crops] (nationalgeographic.com)
Specific types of farmed fish may have small ecological and sustainability footprints
We’ve previously written guides about what the most sustainable animal meats might be, and what the most sustainable overall foods and diets might be.
And, there’s certain farmed fish like atlantic salmon and kelp can can be sustainable and low impact environmentally in some ways as well.
[Specific types of ocean farmed fish have a small ecological footprint, such as Atlantic Salmon]
Atlantic salmon is one of the most energy efficient farmed animals; its carbon footprint is one tenth of the footprint of beef, including the fact that seafood is transported over longer distances to market than meat.
Growing salmon uses significantly less water and space compared to beef too.
– thefishsite.com
In some regions, kelp is a low impact, nutritious, farmed food product:
[Kelp can be] a nutritious food product with no arable land, no fresh water, no fertilizer, and no pesticides [and has the added benefit of cleaning the ocean during production]
– nationalgeographic.com
There can be other miscellaneous sustainability and environmental benefits of aquaculture
… aquaculture production reduces pressures on natural stocks, and environmentally unsustainable methods of capture … (nature.com)
Cons Of Aquaculture & Fish Farming
There can be practical problems with pond based aquaculture
[Some of the practical problems] with pond based aquaculture [might include] deep green pond water, muddy pond water, a red layer on the pond water, oxygen depletion in water, excess ammonia, production of hydrogen sulphide, black mud at the bottom of a pond, large aquatic plants in ponds (researchgate.net)
Even good management by producers may not prevent technical difficulties with aquaculture
… even under good management, several technical difficulties may arise during fish culture with a possibility of large scale loss of production (researchgate.net)
Some farmed fish need wild fish as feed, and it can be resource inefficient when considering feed to production conversion, or place pressure on wild fisheries
What this means is that there may be issues with the sustainability of this approach if fisheries are overfished to keep meeting the demand for feed.
… [some farmed fish species, and] particularly more recently domesticated species like salmon, require wild fish rendered as fish meal and fish oil for their food.
What this means is that most of the time, it takes more than a kilogram of wild fish to create a kilogram of farmed fish
… [one report indicated that the] feed-to-edible product ratio … could be more than 3 kilograms of forage fish to produce 1 kilogram of edible farmed fish
[Although, it should be noted that fish farming has become more feed conversion efficient in recent times]
– earthjournalism.net
Farming carnivorous fish, such as salmon, does not always reduce pressure on wild fisheries
Carnivorous farmed fish are usually fed fishmeal and fish oil extracted from wild forage fish.
– wikipedia.org
The resource footprint of aquaculture can vary
The typical resources required for aquaculture might involve feed (which carries it’s own footprint), water, power used on site, and processing and storage energy used (nature.com)
Energy can come from fossil fuels like coal (nationalgeographic.com)
There’s also effluent and waste management to consider from the farming process
Fish farming can use forage fish species, which can undermine marine food webs and have a secondary impact on other fish species in the wild
… the exploitation of the world’s forage fish is undermining marine food webs.
Some 20 percent of the world catch is now forage fish, the vast majority of which is used for aquaculture feed
– earthjournalism.net
earthjournalism.net has a good graphic where they show how top predator, intermediate predator, first order consumer and primary producer fish species all relate, and what impact consumers are really having when they eat a fish farmed with wild fish feed
There’s potential waste mismanagement issues, and waste pollution to consider with fish farming
[Waste comes in the form of] fecal matter and unused feed [and] These largely nitrogen-based wastes can cause oxygen depletion in coastal environments and a net loss of marine productivity in certain coastal areas
Additionally, the use of antibiotics, antifoulants, and pesticides [can all cause waste pollution in the external environment]
From aquaculturealliance.org:
In the past, when the aquaculture industry was just getting its footing, certain factors inhibited the industry from producing fish sustainably [and] environmental problems did arise [such as] nutrient and effluent build-ups, the impact of fish farms on local wild fisheries with respect to disease and escaping, and environmental degradation due to the site’s location
[Farmed fish can pollute the water] (sustainweb.org)
[Waste and pollutants can result from fish farming] (ecoandbeyond.co)
Can result in disease, abandonment and habitat destruction
[One example of this is when shrimp have been farmed in near coastal mangrove forests in the past. After disease set in, the ponds were abandoned, and the result was the destruction of] hundreds of thousands of acres of mangrove forests – ecosystems critical to the production of wild fish and the protection of the coast from storm surges (earthjournalism.net)
Disease transfer from farmed fish to wild fish is a potential problem
The farming of species in wild environments can be a vector for disease proliferation in the wild environment.
Disease transfer in salmon aquaculture is perhaps the most reported instance of this phenomenon
– earthjournalism.net
[Farmed fish can contribute to parasites and the spread of disease] (sustainweb.org)
Farmed fish escaping into the wild environment might be problematic
[The two issues with farmed fish escaping into both the ocean and land based fresh water sources, and that there’s risk the farmed fish dilute] wild populations’ genetics [and there’s also the chance that farmed fish with high reproduction rates take over a wild environment]
[Farmed fish can can have escapees that impact wild fish populations, and can damage the habitat] (sustainweb.org)
The economics and profitability of fish farming has faced issues in some countries and fish farming industries
One example is catfish in the US across some measures.
[It’s worth noting that catfish have been one of the most commonly farmed species in the US, and the industry has faced a number of economic problems in the past such as] plateaued product prices, increased production costs, international competition and economic recession]
[US market prices for catfish have remained relatively stable for the last twenty years (USDA 2010), while production costs, such as fuel, have steadily increased]
– nature.com
There can be a conflict of interest between production at scale, meeting demand, running at profit and the welfare of the fish
[In some instances, the only way to meet demand and run at a profit in some fish farm systems, is to pack fish into high densities, and there is question over how comfortable this is for the fish] (nationalgeographic.com)
Some slaughter methods are considered to be inhumane
[From an animal rights perspective, some slaughter methods can be considered inhumane compared to others] (wikipedia.org)
Land based salmon may have some sustainability problems when scaling to meet higher demand
[There’s also challenges to land based fish farms …] To grow salmon to market size and meet the global demand would require massive amounts of land, water and energy (thefishsite.com)
Sources
1. Hussan, Ajmal, Gon Choudhury, Tanmoy, T N, Vinay, Gupta, Sanjay, 2016/08/01, 6, 9, Common problems in aquaculture and their preventive measures, 2, Aquaculture Times, Available at https://www.researchgate.net/publication/312947314_Common_problems_in_aquaculture_and_their_preventive_measures
2. https://earthjournalism.net/resources/environmental-problems-of-aquaculture
3. Allen, P. J. & Steeby, J. A. (2011) Aquaculture: Challenges and Promise. Nature Education Knowledge 3(10):12, available at https://www.nature.com/scitable/knowledge/library/aquaculture-challenges-and-promise-23690921/
4. https://www.aquaculturealliance.org/blog/what-is-the-environmental-impact-of-aquaculture/
5. https://www.treehugger.com/aquaculture-problems-inherent-to-aquaculture-1301970
6. https://www.nationalgeographic.com/foodfeatures/aquaculture/
7. https://en.wikipedia.org/wiki/Fish_farming
8. https://www.sustainweb.org/goodcatch/environmental_impacts/#:~:text=Habitat%20damage,can%20cause%20long%2Dterm%20damage.
9. https://www.ecoandbeyond.co/articles/most-environmentally-friendly-meat/
10. https://thefishsite.com/articles/the-flaws-of-land-based-farming
