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
Fish farming and agriculture can be an important method of food production to provide nutrients and protein to a growing population, and in some ways can be a sustainable fishing practice
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 land based conventional agriculture
Various advances and developments are helping to improve fish farming in several ways
The impact and 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)
More sustainable types of fish farming do exist, and it would be worth looking more into these types of fish farming, and seeing how they can match up with the economic profit motive, being able to scale to meet demand, and the well being of the fish being farmed
Pros
Problems with pond based aquaculture can be managed with proper site selection, proper management of soil and water quality [and proper management of the fish culture]
The environmental and sustainability impact of aquaculture can be dependent on controllable factors, and there are some clear solutions to past problems
Some farmed fish can be raised on vegetarian meal/feed
Is a way to increase the food supply for the human population that doesn’t rely sufficient wild animal population numbers
Aquaculture can be profitable as a business
The outlook for aquaculture looks favorable
Aquaculture shows potential to improve in the future terms of production and technological advances, as well as sustainability
Conversion efficiency can be high compared to other types of meat
Might have a higher chance of being free of environmental contaminants
In some cases, aquaculture can increase water quality
Can be used as a form of small business in lesser developed regions
Fish waste can sometimes be used for crop fertilization
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
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
There can be a conflict of interest between production at scale, meeting demand, running at profit and the comfort of the fish
Some slaughter methods are can be considered to be inhumane
*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.
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
Some Of 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
China provides 62% of the world’s farmed fish
Pros Of Aquaculture & Fish Farming
Problems with pond based aquaculture 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)
The environmental and sustainability impact of aquaculture can be dependent on controllable factors, and there are some clear solutions to past problems
… the environmental impact of aquaculture is completely dependent upon the species being farmed, the intensity of production and the location of the farm.
Additionally, new strategies and technologies have emerged and have proven that it is possible to have sustainable aquaculture. [Ultimately, environmental and sustainability based impact can be nuanced]
[siting fish farms in waters with strong currents, paying attention to the density of fish in an area, recognizing 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
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 we’re helping clean the ocean while doing it
– nationalgeographic.com
… 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
Some farmed fish can be raised on vegetarian meal/feed
… some aquaculture species are raised on vegetarian feed [which can come in the form of meals and oils] (earthjournalism.net)
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 (aquaculturealliance.org)
Is a way to increase the food supply for the human population that doesn’t rely on sufficient wild animal population numbers
Obviously fish farming is like land based animal and crop based agriculture – it relies on human induced breeding instead of wild animal population numbers
The one asterisk to this is the feed type used. Obviously if wild caught fish are used as feed, this decreases the legitimacy of using farmed fish as a means of food production that doesn’t rely on wild caught fish to sustain
From aquaculturealliance.org:
Fish farming, when done sustainably, can be the answer to filling the gap in seafood supply that stressed fisheries are creating.
Aquaculture can be profitable as a business
[This can depend on key goals such as] maximizing growth rate and minimizing production costs (nature.com)
[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)
The outlook for aquaculture looks favorable
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)
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
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 terms of production and technological advances, as well as sustainability
[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
[Furthermore] aquaculture production reduces pressures on natural stocks, and environmentally unsustainable methods of capture [and] 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
Conversion efficiency can be high compared to other types of meat
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
The national geographic resource listed has a graphic showing the conversion efficiency of different meats
Read more about the sustainability of different meats in this guide
Might have a higher chance of being free of environmental contaminants
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 regulated (aquaculturealliance.org)
In some cases, aquaculture can increase water quality
[Like for example where] filter-feeders, like shellfish [are farmed] (aquaculturealliance.org)
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 can sometimes be used for crop fertilization
[There is an example in Bangladesh of fish waste being used to fertilizer rice crops] (nationalgeographic.com)
Cons Of Aquaculture & Fish Farming
There can be practical problems with pond based aquaculture
There can be some practical problems with pond based aquaculture such as 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)
Good management 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
… [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
[Of all the farmed organisms, fish might have the best feed conversion efficiency for several reasons to do with requiring less energy -] One of the appeals of aquaculture, both as a profitable business, and as a subsistence provider of protein for human populations, is in 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
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 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
Can result in disease, abandonment 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 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]
There can be a conflict of interest between production at scale, meeting demand, running at profit and the comfort 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, and some can be considered to be more humane] (wikipedia.org)
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
