Atlantic Salmon – Salmo salar

Atlantic salmon is one of the world’s most iconic farmed aquatic species. The majority of farmed Atlantic salmon are cultured in marine net-pens across northern Atlantic countries and along the west coast of the Americas.

Globally some 2.25 million tonnes of Atlantic salmon was produced in 2016. Norway, Chile and Scotland were the three largest producers, with a combined output of 85.8% of world production.

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Profile last updated: 27th Nov 2019

Sources, Quantities and Cultivation Methods

Sources and Quantities
Atlantic salmon (often known simply as ‘salmon’)1 is native to the North Atlantic and its islands (e.g. UK, Iceland, Greenland, etc.). Wild Atlantic salmon are anadromous; spending their adult life in the sea but swimming upriver to freshwater spawning grounds. After hatching, young salmon stay in rivers as parr for 1-5 years before undergoing physiological changes (smoltification) that enables them to migrate out to the open ocean. They head for deep water feeding grounds, and after 1-4 years the mature fish return to their home rivers to spawn2.

Wild populations of Atlantic salmon are generally at low levels and capture fisheries have seen significant decline2. Commercial fishing is now limited. Almost all commercially available Atlantic salmon is farmed and from locations with the necessary environmental and geographical characteristics (i.e. water temperature and indented coastlines).

Apart from being farmed across its native range Atlantic salmon are also cultured as a non-native species along the coast of North America’s Pacific Northwest (i.e. British Columbia) and in countries such as Chile and Tasmania.

Atlantic salmon is one of the most important farmed finfish species in the world and its production is highly efficient. Global production has increased markedly since the early 1990’s from around 30,510 tonnes in 1993 to over 2.25 million tonnes in 2016, valued at almost US$14.4 billion3.

As the map shows, Norwegian production is dominant and is over double that of its closest competitor, namely Chile. The UK (Scotland) and Canada are the other two major producers. These four countries represented almost 91% of world Atlantic salmon production in 20163. During the last decade the salmon farming industry has seen a period of consolidation and production in each of the ‘big four’ is undertaken by five to ten companies4. Many of these companies are global enterprises with facilities in multiple countries.

Europe (including Russia) and North America are by far the largest markets for Atlantic salmon. However, emerging markets (such as Brazil and Asia) are growing at significantly higher rates than these traditional markets4. Farmed salmon is now Scotland’s largest food export by value and over 50 countries imported Scottish salmon in 2016, with the US and France being the largest markets5. Scottish salmon was the first fish and first non-French product to be awarded the Label Rouge quality mark6.

Domestic Market Information7, 8
‘Salmon’ has grown to dominate the seafood market in Great Britain (i.e. England, Scotland and Wales) in terms of both value and volume, the majority of which is farmed Atlantic salmon. From 2008 to 2017 salmon was the only one of the top five seafood species to show market growth despite having a relatively high average price. In 2018 the long-term run of volume growth ended; as value grew by 51.2% and volume declined by -4.8% from a base of £611m and 54,361 tonnes in 2008, and the significant inflation impacted on shoppers value for money perception. Salmon has the highest average price of any of the top ten seafood species; over double that of cod and haddock.

In June 2018 UK salmon retail sales were worth £1,056 million (+3.6% compared to June 2017) with a volume of 62,190 tonnes (-8.5%), average price £16.98 per kg; still ranking as the most popular UK seafood by value and volume (in the 52 weeks up to 16/06/2018 (including discounters)).

In 2018, the UK imported a total of 84,190 tonnes of salmon, including 58,028 tonnes of chilled Atlantic salmon.

Note: the difference between the volume of salmon sold in UK retail and that which is imported is due to its use in the foodservice industry (e.g. restaurants) (no data available) and that which is re-exported.

Production Method
Atlantic salmon farming replicates the species natural cycle. It is divided in to two phases; freshwater – hatchery and smolt production, and seawater – growing the fish through until harvest4, 9, as shown in the production schematic.

Selected adult broodstock are stripped of eggs and milt (sperm), and the eggs are fertilised.  The first life stage or alevin have a yolk-sac and once absorbed they become free swimming fry and then develop further in to parr.  These initial stages take place in freshwater tanks and the fry and parr are fed commercially available pelleted feeds tailored to their specific requirements. Parr develop further into smolts and at this stage they are ready to go to sea.

Traditionally in Scotland, parr are transferred to net-pens in freshwater lochs for further on-growing into smolts. Whilst this method is still important, industry is increasingly using sophisticated onshore recirculation systems which provide producers with greater control and faster growth rates;  producing larger smolts and shortening the seawater grow-out phase10, 11.

Smolts can be transferred to the sea net-pens by several methods, including road, helicopter and well-boat. Once in the sea pens, the fish are fed a pelleted diet that is, again, tailored to their needs. The majority of Atlantic salmon are harvested after 14-20 months at sea, depending on the location12.

Fish are harvested at a size depending on the requirements of their destination market. Increasingly, the fish are transferred from the net-pens to a well-boat (a vessel with wells or tanks for the storage or transport of live fish) and transported to a shore-based harvest facility, where they are humanely stunned, bled and prepared for market. In Scotland a significant proportion of fish are now harvested directly into well-boats and ‘dead hauled’ to processing plants12.

  1. Defra (
  2. FAO (
  3. FAO FishstatJ (
  4. Marine Harvest (
  5. SSPO (
  6. SSPO (
  7. AC Nielson (
  8. HMRC (
  9. FAO (
  10. HIE (
  11. Ellis, T., et al, 2016. Trends during development of Scottish salmon farming: An example of sustainable intensification? Aquaculture 458, 2016 p82-99 (
  12. SSPO, pers. comm., 2018

Governance and Outlook

Governance systems play an important part in ensuring environmental sustainability, and whilst these have evolved rapidly with the growth of the industry, there are differences between regions and countries. Poor governance can result in industry stagnation, the spread of preventable diseases, environmental damage and opposition to aquaculture activities by local communities and groups such as non-governmental organisations (NGOs). Key governance responsibilities are ensuring environmental assessment and decision making processes are in place for sensitive and coastal ecosystems, which help deliver sustainable aquaculture whilst managing possible adverse impacts. Other regulatory and governance aspects should cover aspects such as water abstraction and discharge, health monitoring, and so forth.

Four principles – accountability, effectiveness and efficiency of governments, equity, and predictability of the rule of law – are necessary for effective aquaculture governance. These principles should guide the administrative, legislative and regulatory framework of aquaculture. In addition to governments, other stakeholders such as communities, NGOs and producers should also be involved in the governance of the industry1.

Atlantic salmon farming is predominantly undertaken in three global regions; Europe, North America, and Latin America, and generally in economically advanced countries with good and/or improving governance structures in place.

Europe & Norway2
The shaping of regulations and the instruments for the development of and investment in most of the aquaculture sector in Europe falls under the European Union (EU). These regulations and instruments are highly evolved and are intended to stimulate and guide aquaculture development which is environmentally, socially and economically sustainable. In non-EU member states (such as Norway) there are largely equivalent policies.

North America3
National and provincial/state governments in both Canada and the US have articulated strategies for the development of aquaculture in North America, and governance systems are highly evolved. The thrust of aquaculture development in Canada is focused on environmental sustainability. In the US, development is also geared toward sustainability with offshore expansion.

Latin America (Chile)4
Whilst concerns have been raised as to the effectiveness of salmon aquaculture governance in Chile5, 6, efforts to regain efficiency and environmental stability continue7 and stricter regulations are now considered to be in place8. The Environmental Regulation on Aquaculture Act (2001) requires the preparation of a ‘Preliminary Characterization of Site’ study, for the determination of the physical, biological and chemical parameters and variables of the project area. According to the General Law on the Environment (1994), the conduct of aquaculture is also subject to an Environmental Impact Assessment (EIA). Therefore, authorizations and concessions are issued through the EIA System.

In all salmon producing regions, the relevant authorities have licensing regimes, and salmon farming businesses typically need to obtain a site licence to operate9. Before a site license is granted an environmental impact assessment is often required. This will typically involve modelling the potential impact of waste faeces, feed and chemicals that may be dispersed from the farms. Licencing information relating to the big four Atlantic salmon producing countries is available, i.e.; Scotland – Fish Farm Consents10, Norway – Licence requirements in aquaculture11, Canada – Aquaculture Businesses and Licences12, Chile – Regulated Activities: Aquaculture13.

The global farmed salmon industry also has codes of practice and technical standards (such as those in Scotland14, 15), as well as independent 3rd party certification standards and industry initiatives which all aim to instil responsible and sustainable practice.

Farmed Atlantic salmon is increasing, with producers aiming to significantly raise, even double production over the coming years16, 17, 18. There is growing interest in utilising new technologies and practices to enable such growth; for example producing market size fish in recirculating aquaculture systems (RAS), moving net-pens to further offshore locations and/or using closed containment units19. Integrating production with other aquaculture species such as seaweeds and filter feeding shellfish (so called Integrated Multi-trophic Aquaculture, IMTA) is also being investigated20. How successful these new models will be remains to be seen.

The Global Salmon Initiative (GSI)21 is a leadership initiative set up by global farmed salmon producers. Its aim is to provide healthy and sustainable protein to feed a growing population, whilst minimising salmon’s environmental footprint, and improving its social contribution. Focus areas are biosecurity, standards, feed and nutrition, and improving industry transparency. The GSI was launched in 2013 and now has 12 members with operations covering eight countries. Currently representing over 50% of the global farmed salmon by production volume, GSI members have committed to achieving Aquaculture Stewardship Council (ASC)22 certification across 100% of its farms by 2020.

Genetically Modified Salmon
In 2015, the Food and Drug Administration (FDA) in the US announced that a strain of genetically modified (GM) Atlantic salmon that reportedly grows faster than non GM strains of salmonids is safe for consumers23, and a facility has recently been approved for its commercial production24. The use of GM Atlantic salmon is not currently practiced or authorised in European producer countries and current market preferences in the UK suggest that it would be unlikely that GM fish would be accepted in the foreseeable future.

  1. FAO (
  2. FAO (
  3. FAO (
  4. FAO (
  5. Bustos-Gallarado, B., 2013. The ISA crisis in Los Lagos Chile: A failure of neoliberal environmental governance? Geoforum, 48, 2013. p196-206 (
  6. Salgado, H. et al, 2015. Stakeholder perceptions of the impacts from salmon aquaculture in Chilean Patagonia. Ocean & Coastal Management, July 2015 (
  7. FAO (
  8. Reuters (
  9. Marine Harvest (
  10. Scottish Government (
  11. Norwegian Ministry of Trade, Industry and Fisheries (
  12. Fisheries and Ocean Canada (
  13. SUBPESCA (
  14. Code of Good Practice for Scottish Finfish Aquaculture (
  15. Marine Scotland (
  16. Fish Farming Expert (
  17. Fish Farming Expert (
  18. The Fish Site (
  19. Nofima (
  20. Institute of Marine Research, Norway (
  21. GSI (
  22. ASC (
  23. FDA (
  24. Seafood Source (

Farm Siting

Open Water Net-Pens
Appropriate siting, design and construction of Atlantic salmon cage farms is essential to limit adverse impacts on the environment and natural ecosystems. In addition, if floating net-pens are located within navigable water bodies, consideration should be given to ensure that they do not impinge and restrict movement of boats, aquatic animals and the water itself. There may also be concerns over the visual impact of siting net-pens in the areas of natural beauty; in such areas it is important that the design, construction and colour of farm facilities are sympathetic with the landscape in which they sit.

As Atlantic salmon net-pens are often located in areas with relatively rich wildlife, species that prey on fish can be attracted to them (e.g. seals, cormorants). This can potentially become a significant problem for a farmer due to the stress caused to the stocked fish and injuries caused to them. In the worst case scenario there could be significant losses to stock and/or escapes if predators breach net-pens.

National and local laws should be adhered to and all farms should have the required licences, permits and registrations in regards to their site and its operations, with documentation being kept to evidence compliance. Where aquaculture development plans exist, then new farms should be located within the appropriately identified areas. Salmon producing countries are increasingly creating policies and using marine spatial planning to regulate where aquaculture can take place in relation to other farms and other marine users (e.g. appropriate areas where production is allowed, including allowable production densities, the use of appropriate infrastructure, and so on)1, 2. Marine cage culture has ‘minimal’ impacts to the environment where farms are appropriately sited and properly managed3.

Atlantic salmon net-pens should be located, constructed, and have management measures in place to mitigate entry and damage by predators. Non-lethal control methods are available to the industry and considered good practice4. Deterrents, scarers and increased on-site activity may be effective.  Lethal methods of predator control should only be resorted to when appropriate licences are in place and the predatory species are not threatened in any way.

On-Shore Facilities
Land-based aquaculture facilities involve a greater level of complexity and utilise more technical equipment than open-water systems (e.g. net-pens), especially intensive salmon smolt production with numerous growing units5, 6. Major components include:

  • Water abstraction and transfer
  • Water treatment and wastewater discharge
  • Production units
  • Equipment and space for: feeding / feed storage; internal fish transport and size grading; transport of goods and services in and out (e.g. feed, staff, harvested fish); monitoring of the culture environment (e.g. water quality parameters)

There are many factors to be considered in locating a land-based aquaculture facility. Many will be project-specific depending on the type and scale of the operation and the environmental requirements needed by the cultured species (e.g. temperature, salinity, etc.)7. Land-based RAS are currently only economical for the freshwater stages of Atlantic salmon production, but there is increasing interest in farming salmon in these systems to market size8.

The physical and locational requirements for a large RAS facility include access to supporting infrastructure such as power, road and sea links, whilst being sited on an adequate land area that is easily developed and low enough and close enough to water levels in order to reduce pumping costs7. Energy is one of a number of critical operating costs that influence the location RAS farm developments9. On-shore aquaculture systems often require large buildings, may increase road traffic (e.g. goods and service flows) and generate noise (e.g. generators, pumps, compressors). These impacts may be of concern if located in sensitive areas.

Designing, building and operating on-shore aquaculture facilities must be undertaken with due regard to the sensitivities of the local area (e.g. not disturbing the skyline, screening by trees or other structures, respect for other local amenities/users), and work as best it can with local infrastructure (e.g. road capacity). Working through the necessary planning policies is vital. Capital costs for land purchase (or land rental charges) needs to be appropriate in order to make an on-shore aquaculture facility viable5. As RAS are isolated from the external environment they can be extremely biosecure and as such predator risks can be eliminated.

  1. Scotland’s National Marine Plan (
  2. FAO/World Bank (
  3. NOAA (
  4. Code of Good Practice for Scottish Finfish Aquaculture (
  5. SARF (
  6. Lekang, O-I., 2007. Aquaculture Engineering. Blackwell Publishing
  7. Cawthron Institute (
  8. Fish Farming Expert (
  9. HIE (

Nutrient Pollution

Feed is a major component of the cost of farmed salmon production and the efficient use of feed is an important aspect of farm management – to ensure that as much of the feed as possible is consumed by the fish and that as little as possible is wasted. Efficient monitoring and management of feed regimes minimises nutrient discharges from salmon net-pen farming and reduces the potential of pollution arising from uneaten food entering the marine environment. This is important as the accumulation of uneaten food and faecal matter beneath net-pens has the potential to affect aquatic life through de-oxygenation and algal blooms which can be associated with nutrient increase. The key nutrients likely to cause problems for receiving waters are nitrogen and phosphorus.

In addition to controlling the amount of feed dispensed to the fish, salmon diets have improved to make them more digestible. This results in greater food absorption, less faecal production, and computer controlled demand feeding systems result in less food use and wastage.

Licensing and farm management can ensure facilities are located in areas where the potential environmental impact from the release of nutrients are minimal, and this includes undertaking full environmental impact assessments, including modelling impacts of release of nutrients before licenses are issued. As technology has developed salmon net-pens have been able to locate to more exposed locations with stronger currents and in deeper water, and this ensures waste materials are more widely dispersed. Net-pens are also regularly rotated between farm sites to enable fallowing. The regulatory framework has also become more sophisticated1. In Scotland for example the regulation of discharged wastes is exercised through Controlled Activities Regulations2.

Another proposed solution towards ameliorating inputs from net-pen farming is the adoption of IMTA, whereby filter feeders (shellfish), detritivores (e.g. sea cucumbers or marine worms), and macro-algae (seaweeds) are grown alongside the salmon farms to remove the various outputs from the fish.  Whilst this solution has initial appeal, it has yet to demonstrate its viability in biological, environmental and financial terms, when it is applied to the dynamic open sea environment3.

Land-based RAS can mitigate nutrient pollution risks by removing solids prior to the discharge of effluents and the removal of dissolved nutrients in waste water streams by establishing areas such as reed beds.

  1. Little, D. and Shepherd, C.J., 2014. Aquaculture: are the criticisms justified? II – Aquaculture’s environmental impact and use of resources, with special reference to farming Atlantic salmon (
  2. Marine Scotland (
  3. Institute of Marine Research, Norway (


Fish Meal and Fish Oil
Marine ingredients such as Fishmeal (FM) and Fish Oil (FO) provide nutrients that often cannot be found in other feed materials (e.g. particular amino acids, vitamins and minerals), and they are essential constituents of many aquafeeds. FM and FO are a finite resource and are seen by the aquaculture industry as a strategic ingredient to be used efficiently and replaced where possible1.

Globally the FM and FO used in aquafeeds is increasingly derived from fishery and aquaculture processing by-product; the utilisation of these by-products as a raw material for FM and FO production is in the region of 25%-35% and this trend will continue; it is expected to rise to 49% by 20221, 2, 3.

IFFO The Marine Ingredients Organisation4 (formerly known as The International Fishmeal and Fish Oil Organisation or IFFO) estimate that if aquaculture is taken as a whole, producing one tonne of fed farmed fish (excluding filter feeding species) now takes 0.22 tonnes of whole wild fish. This essentially means that for every 0.22 kg of whole wild fish used in FM production, a kilo of farmed fish is produced; in other words, for every 1 kg of wild fish used 4.5 kg of farmed fish is produced5.

Perhaps the most important mitigation measure is to ensure that products such as FM and FO used to manufacture aquafeed come from legal, reported and regulated fisheries. Such fishery products can demonstrate their sourcing adheres to the United Nation Food and Agriculture Organisation (UN FAO) “Code of Conduct for Responsible Fisheries”6, known as CCRF, through several mechanisms:

  • The Marine Stewardship Council (MSC)7 which certifies fisheries to an international standard based on FAO best-practice requirements
  • IFFO RS Global Standard for Responsible Supply (IFFO RS)8 which certifies FM and FO through a process which includes the assessment of source fisheries against a set of CCRF-based requirements
  • Information platforms such as FishSource9 or FisheryProgress10 which provide information and analysis without a certification or approval rating

Currently around 1.9 million tonnes of FM production is certified as either IFFO RS or MSC – representing about 40% of global production; most of this comes from South America, but Europe and North America are providing significant volumes, and North Africa currently has certified production. Currently there is no certified FM product produced in China and only very small quantities (less than 10,000 tonnes) are produced in the rest of Asia (and this is from by-products)2.Aquaculture certification schemes also require that fish products used in feeds are not on the International Union for Conservation of Nature (IUCN) red lists11 of threatened species or the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES)12 lists of endangered species.

GM Feed Ingredients
The use of genetically modified (GM) vegetable ingredients in animal feedstuffs (including aquafeed) is an ongoing area of debate13. Whilst some contend that GM soy can help support current levels of aquaculture, global attitudes and consumer perceptions about the use of Genetically Modified Organisms (GMOs) vary in different parts of the world, with North American markets being far less averse than European ones. However, their use in all livestock feed is widespread, and in the EU food from animals fed on authorised GM crops is considered to be as safe as food from animals fed on non-GM crops14.

Atlantic salmon Feed
Careful management of food and feeding regimes are important to the success of salmon aquaculture. To reduce wasting aquafeed on farms, efficient feed use can be monitored and should comply with levels set in certification standards. The indicators used can include the Feed Conversion Rate or FCR (the amount of feed an animal requires to gain a kilogram of body weight), economic feed conversion ratio (eFCR), maximum fish feed equivalence ratio (FFER), or protein efficiency ratio (PER).

Atlantic salmon have a requirement for a high protein diet and whilst their aquafeeds are still relatively high in FM and FO, vegetable materials are increasingly substituting these marine ingredients. The graph shows that in 1990 90% of the ingredients in Norwegian salmon feed were of marine origin, whereas in 2013 it was only around 30%15, and this trend is set to continue.

In terms of feeding efficiency, the average FCR figure for Atlantic salmon is low at around 1.116, and improvements in FCR has reduced the feed requirement per tonne of salmon produced by around 60% since the 1980s17. IFFO The Marine Ingredients Organisation estimate that in 2015 for every 0.83 kg of whole wild fish used in FM production for all salmonids (i.e. salmon and trout) aquafeeds, a kilo of farmed salmonids are produced. This means that the salmonid feed industry supports the production of more farmed fish than it uses as feed fish, which appears to be the first time this has been recorded5.

As feed companies constantly develop their aquafeed formulations the decreasing inclusion of marine ingredients will not only continue in salmon feeds but in those for a number of other aquaculture species.

Flesh Pigments
The pink colour of salmon flesh, wild or farmed, results from the retention of carotenoids in the fish flesh. Astaxanthin is a naturally occurring carotenoid pigment18 found in wild salmon and crustaceans. Salmon cannot make their own astaxanthin; they consume it in their diet. The wild salmon diet includes krill, zooplankton, small fish and crustaceans all of which naturally contain astaxanthin. There are several health benefits from astaxanthin for salmon; it is a potent antioxidant and a source of vitamin A and helps to protect tissues, stimulate the immune system and improve fertility and growth19. In order to confer these health benefits to farmed Atlantic salmon, astaxanthin (either natural or synthetic) is introduced into their pelletised feed whilst in the seawater grow-out phase.

There is no difference between the natural and synthetic forms of astaxanthin; both are processed and absorbed by wild and farmed fish in exactly the same manner19, 20. Both natural and synthetic forms are considered safe for use in salmon diets, and their use up to the maximum permitted dietary level for salmon is of no concern for consumer safety21, 22. Seafood buyers often use colour charts such as a ‘Salmofan’23 to compare different salmon flesh colour, and whether the pigment used is natural astaxanthin (extracted from crustacean shell, Phaffia yeast24, or predominately from the bacteria Paracoccus carotinifaciens producing the pigment Panaferd 25) or synthesized, depends on the requirements of the particular brand or retailer.

  1. IFFO (
  2. IFFO (
  3. Seafish (
  4. IFFO (
  5. IFFO (
  6. FAO (
  7. MSC (
  8. IFFO RS (
  9. FishSource (
  10. FisheryProgress (
  11. IUCN (
  12. CITES (
  13. Sissener, N.H. et al, 2011. Genetically modified plants as fish feed ingredients. Canadian Journal of Fisheries and Aquatic Sciences, 2011, 68(3) p563-574 (
  14. FSA (
  15. Ytrestøyl, T. et al, 2015. Utilisation of feed resources in production of Atlantic salmon (Salmo salar) in Norway.  Aquaculture, Vol. 448, 2015 p365–374 (
  16. Marine Harvest (
  17. Little, D. and Shepherd, C.J., 2014. Aquaculture: are the criticisms justified? II – Aquaculture’s environmental impact and use of resources, with special reference to farming Atlantic salmon (
  18. Mahfuzur R., et al, 2016. Astaxanthin-Producing Green Microalga Haematococcus pluvialis: From Single Cell to High Value Commercial Products. Frontiers in Plant Science, Vol 7, 2016 (
  19. Skretting (
  20. NOAA (
  21. European Food Safety Agency (
  22. FSA (
  23. DSM (
  24. Sanderson, G.W. and Jolly, S.O., 1994. The value of Phaffia yeast as a feed ingredient for salmonid fish. Aquaculture, Vol 124, Iss 1–4, 1994 p193-200 (
  25. JXTG Group (

Disease, Medicines and Chemicals

In common with all other animal farming systems in which animals are raised in greater numbers than they would be found in nature, the farming of Atlantic salmon can potentially increase the risk of disease outbreaks due to the number of individual animals living in close proximity to each other. It is essential that good husbandry and a pro-active approach to health management is adopted at each farm location in order to minimise and mitigate these risks.

Atlantic salmon can be affected by a range of viral and bacterial pathogens, the most important of which cause: Pancreas Disease (PD), Salmonid Rickettsial Septicaemia (SRS), Infectious Pancreatic Necrosis (IPN), Heart and Skeletal Muscle Inflammation (HSMI), Infectious Salmon Anaemia (ISA), and Gill Disease (GD)1. The effects of disease can have major economic impacts on the industry, for example the ISA outbreak in Chile2.

The first line of defence in disease and pathogen management is effective biosecurity and health plans to minimise disease and its spread3, 4. Certification schemes require such plans, as do other initiatives, e.g. The Code of Good Practice for Scottish Finfish Aquaculture5.

When needed, there are a range of medicines and chemical treatments available to control Atlantic salmon disease and pathogens, including antibiotics. Antibiotics are used strictly as therapeutants by the industry; they are not used as growth promoters. Overuse of antibiotics in farming or for human medical treatment speeds up the development of antibiotic resistance, which is when bacteria change and become resistant to the antibiotics used to treat them6. Generally only limited amounts of antibiotics are used rearing Atlantic salmon due to the availability and efficacy of vaccines7.

Across many Atlantic salmon producing countries antibiotic use has fallen significantly1, 7 as shown in the graph, whilst in some producer countries this has not been the case, e.g. in Chile8, 9, 10, 11, 12. However, reductions in Chilean usage have recently been reported13.

Strict adherence to medicine withdrawal periods at farm level, and through pre and post-harvest testing regimes, it is possible to assure seafood buyers and consumers that any residual levels of antibiotics in the edible parts of the fish fall within legal tolerances acceptable in human food.

Vaccination plays a very important role in Atlantic salmon farming, and has been a key reason behind the success of salmon aquaculture. The industry has adopted mass vaccination to control a number of diseases found in freshwater and marine environments, and in many cases smolts are injected with vaccines that provide broad protection against a range of diseases14, 15.

Medicinal treatment (vaccines, antibiotics and chemical treatments) used by Atlantic salmon producers is tightly regulated and normally administered by a veterinarian. Typically, only approved medicines that are authorised to treat a particular disease can be used. For example, in the UK industry, supply and control of medicines is regulated by the Veterinary Medicines Directorate16 which maintains an up-to date list of authorised products that can be used in salmon as well as other food species. Similar controls exist in Norway, the US, Canada and to a large extent Chile. Regulators ensure that treatments are effective and safe to the target animal and the environment; consumer safety is ensured by specifying withdrawal periods after treatment and before fish are harvested.

Functional aquafeeds include a range of additives used to improve growth and feed utilisation, but also to support the health and stress resistance. Additives, such as probiotics, prebiotics, phytogenics, and immune-stimulants may help improve disease resistance and reduce the intensity of sea lice infection17, 18, 19.

Good husbandry and strict adherence to the principles of biosecurity are also an important aspect of managing the movement of eggs and live fish between sites, including in some cases internationally, where there is an opportunity to spread pathogens between locations.

Sea Lice
Sea lice (a parasitic copepod) feed on salmon skin and can cause lesions, leading to further problems and secondary infections. Although wild Atlantic salmon are natural hosts of sea lice the possible interaction and impacts on wild fish populations of sea lice from farmed fish is a concern20, 21, 22 and the management of sea lice is perhaps the most pressing issue facing the Atlantic salmon aquaculture industry. Biosecurity plans to minimise sea lice are central to health management and are now widely implemented. These include processes to separate different stocks and year-classes of fish, control of the movement of equipment and staff between premises, disinfection of key equipment, and introduction of fallowing periods between stocking net-pen sites with new cohorts of fish.

At national and regional levels, governments are increasingly implementing area management plans that regulate how the salmon industry operates in particular zones alongside developing improved treatment programmes. The Scottish Government for instance, helps the industry to operate within disease management areas23, whilst in Norway sea lice levels on a regional basis will dictate the industry’s growth and production capacity24.

Treatments for sea lice control constitute the greatest use of any of the range of medicines and chemical treatments used to control Atlantic salmon disease and pathogens. There are concerns that these treatments may have environmental impacts if released in to the water column. In Scotland, Norway, and increasingly in other countries, the recently developed practice of treating fish within well-boats (vessels with wells or tanks for the storage or transport of live fish) prevents this25. There is also concern that resistance to some sea lice chemical treatments is developing26.

Administration of sea lice medicinal treatment is tightly regulated to minimise potential environmental impact and can normally only be done by a veterinarian. There are significant efforts to identify and use alternative non-medicinal delousing treatments: breeding programmes to increase resistance; better monitoring and management procedures; functional feeds; and engineering solutions such as hydrolicing, which uses low-pressure water jets to dislodge sea lice, and thermolicing, whereby fish are bathed in warmer water to separate the lice from the fish27, 28. There is an increasing interest in the use of biological delousing approaches; so-called cleaner fish (wrasse species and lumpsucker) that are introduced into the net-pens with the reared salmon and graze on the sea-lice29, 30, 31. A combination of treatments, techniques and technologies will be needed by the Atlantic salmon industry to manage and combat sea lice.

RAS Facilities
One of the advantages of RAS technology is the improved level of biosecurity provided, with the opportunity to reduce disease outbreaks and eliminate some diseases altogether. RAS can control environmental conditions leading to more stability and favours reduced disease outbreaks. Biosecurity in RAS needs to be extremely tight; introduced parasites or pathogens in RAS systems can be very hard to control due to the difficulty of and reluctance by the system manager to disinfect biological filters. Producing larger, more robust smolts in RAS reduces the marine grow-out phase and the opportunity for disease and pathogen loads to develop could also be reduced30.

  1. Marine Harvest (
  2. Asche F. et al, 2010. The Salmon Disease Crisis in Chile. Marine Resource Economics, Vol 24 p405–411
  3. FHI (
  4. Lillehaug, A. et al, 2015. Practical biosecurity in Atlantic salmon production. Journal of Applied Aquaculture 27(3), 2015 p249-262 (
  5. Code of Good Practice for Scottish Finfish Aquaculture (
  6. WHO (
  7. Norwegian School of Veterinary Science (
  8. FISHupdate (
  9. Fish Farming Expert (
  10. Seafood Watch (
  11. FiS (
  12. Reuters (
  13. OCEANA (
  14. Sommerset, I. et al, 2015. Review: Vaccines for fish in aquaculture. Expert Review of Vaccines, Vol 4, 2005 (
  15. Ellis, T. et al, 2016. Trends during development of Scottish salmon farming: An example of sustainable intensification? Aquaculture 458, 2016 p82-99 (
  16. VMD (
  17. Encarnacao, P., 2016. Functional feed additives in aquaculture feeds. Aquafeed Formulation, 2016 p217-237 (
  18. International Aquafeed Magazine (
  19. Cargill (
  20. Torrissen, O. et al, 2013. Salmon lice – impact on wild salmonids and salmon aquaculture. Journal of Fish Diseases 2013, 36 p171–194 (
  21. Martya, G.D., et al, 2010. Relationship of farm salmon, sea lice, and wild salmon populations. Proceedings of the National Academy of Sciences of the United States of America, 2010, Vol 107, No. 52 (
  22. Callander McDowell: reLAKSation (
  23. Scottish Government (
  24. FiS (
  25. FISH Update (
  26. Aaen, S.M. et al, 2015. Drug resistance in sea lice: A threat to salmonid aquaculture. Trends in Parasitology 31(2), 2015 (
  27. SARF (
  28. Seafood Source (
  29. GSI (
  30. SARF (
  31. Imsland, A.K. et al, 2014. The use of lumpfish (Cyclopterus lumpus L.) to control sea lice (Lepeophtheirus salmonis Krøyer) infestations in intensively farmed Atlantic salmon (Salmo salar L.). Aquaculture s 424–425, 2014 p18-23 (

Escapes and Introductions

Escapees from aquaculture facilities can potentially impact on habitats and species in the receiving water bodies. Problems could occur due to competition, potential disease transfer, establishment of non-native species, interbreeding with wild populations, and impacts on sensitive habitats.

The contribution of non-native species to the growth of the global aquaculture industry and the economic benefits that it has brought to many countries cannot be underestimated. However, minimising the escapes of non-native aquaculture species must be a high priority for resource managers, conservationists and the aquaculture industry1. Atlantic salmon is farmed on large-scales as a non–native species (in Chile, west coast North America, Tasmania ,but the species has been shown to be a poor colonizer2, 3, and research to date has not shown farming salmon has led to the establishment of viable populations in the wild of non-native species4.

There are also concerns that farmed salmon, which come from selected breeding programmes, will interbreed with wild salmon populations if they escape; damaging the native population genetic integrity and weakening wild stocks (genetic introgression). However, this requires that farmed salmon escapees survive until maturation, successfully reproduce and produce viable offspring, and these traits are often compromised in domesticated animals reared in captivity1 2. Genetic introgression has been demonstrated in wild salmon2, 5 but proven deleterious effects have yet to be detected and there is little scientific evidence to support claims that salmon farming has caused the widespread declines in wild salmon fisheries6.

With any open water containment system there is the potential for stock to escape and prevention is the key to mitigating Atlantic salmon escapes. Escapes from farms can occur both through repeated low-number incidents and through large-scale events. Technical and operational failures can lead to escapes: cages can be breached in storms; holes can appear through wear and tear; predator interaction and operational accidents can occur, and so on. Improvements to salmon net-pen design/standards and farm management have led to reductions in escapes7, 8, 9.

Losses due to escapes represent a considerable financial loss to a farm, so it is in its interest to prevent them. Mitigation should ideally include the following five elements10:

  • Mandatory reporting of all escape incidents
  • Establishment of mechanisms to analyse and learn from escape reporting
  • Conduct mandatory, rapid, technical assessments to determine the causes of escape incidents involving large numbers of fish
  • Introduction of technical standards for sea-cage aquaculture equipment coupled with an independent mechanism to enforce the standard
  • Mandatory training of fish farm staff in escape-critical operations and techniques

Recapturing fish after escape (at or close to the point of escape) is a logical management option, however evidence suggests that fish tend to disperse rapidly from the point of release and recapture efforts are often delayed after large-scale escape events, which typically occur during storms. These two factors mean that few attempts to recapture salmon after large-scale escape incidents have been successful11.Improved netting materials, enhanced engineering standards and equipment build quality, better staff training around vessel handling and use, and efforts to deter predators, have done much to reduce escape incidents from net-pens12, 13, whilst the biosecurity of land-based RAS facilities means that escape risks are minimal within these systems.

  1. Cook, E.J et al, 2007. Non-Native Aquaculture Species Releases: Implications for Aquatic. (Chapter 5 in Aquaculture in the Ecosystem, p155-184)(
  2. Heino, M. et al, 2015. Genetic introgression of farmed salmon in native populations: quantifying the relative influence of population size and frequency of escapees. Aquaculture Environment Interactions, Vol 6, 2015 p185–190 (
  3. Seafood Watch (
  4. ASC Salmon Standard (
  5. Karlsson, S. et al, 2016. Widespread genetic introgression of escaped farmed Atlantic salmon in wild salmon populations. ICES Journal of Marine Science 73(10), 2016 (
  6. Little, D. and Shepherd, C.J., 2014. Aquaculture: are the criticisms justified? II – Aquaculture’s environmental impact and use of resources, with special reference to farming Atlantic salmon (
  7. Seafood Watch (
  8. Seafood Watch (
  9. Seafood Watch (
  10. Jensen, O et al, 2010. Escapes of fishes from Norwegian sea-cage aquaculture: causes, consequences and prevention. Aquaculture Environment Interactions, Vol 1, 2010 p71–83 (
  11. Dempster, T. et al, 2016. Recapturing escaped fish from marine aquaculture is largely unsuccessful: Alternatives to reduce the number of escapees in the wild. Reviews in Aquaculture, April 2016 (
  12. Marine Scotland (
  13. Bridger, al, 2015. Physical containment approaches to mitigate potential escape of European-origin Atlantic salmon in south coast Newfoundland aquaculture operations. DFO Canadian Science Advisory Secretariat Research Document, 2015 (


Aquaculture (and fisheries) certification and labelling programmes have become a primary tool to address sustainability issues of farmed seafood, and the development of third party assessment and certification has provided new forms of governance traditionally dominated by state-based regulation1, 2. The growth in the number of certification schemes has led to confusion surrounding the myriad of them out there. To try and combat this, the Global Sustainable Seafood Initiative (GSSI)1 has developed its global benchmarking tool to measure and compare certification schemes and standards performance across seafood production.

Given the prominence of environmental issues as the driver for the development of aquaculture standards, there is an understandably strong emphasis on environmental criteria within them3. Certification enables aquaculture producers to voluntarily demonstrate their responsible farming practices by: complying with national legislation; minimising impact on habitats and wildlife; making the best use of locally available resources; and ensuring the best use of feed and therapeutic products.

Aquaculture certification currently has moderate to high coverage of labour standards (e.g. minimum wage)3, however, increased social and economic requirements related to human rights, gender and sustainable livelihoods are being developed.

Since 2011, a partnership of UK businesses called the Sustainable Seafood Coalition (SSC)4 have been working to ensure all fish and seafood sold in the UK comes from sustainable sources, and aquaculture certification plays a pivotal role. All members need to ensure that the aquaculture source (considering feed mills, hatcheries, and farm sites) is certified under a third party standard, or audited to a members own good aquaculture standard or code of practice5.

The table below looks at some of the major aquaculture certification schemes, including those for salmon, and if they address the Key Considerations highlighted throughout the profiles. It also highlights which scheme has a standard/s successfully benchmarked by the Global Sustainable Seafood Initiative (GSSI)1.

Read more about aquaculture certification, including that of salmon, after the table.

Certification Scheme: Description and Links Governance Farm Siting Nutrient Pollution Feed Disease, Medicines & Chemicals Escapes & Introductions Wild Seed GSSI Benchmarked

Aquaculture Stewardship Council (ASC)

Founded in 2010 by WWF and IDH (Dutch Sustainable Trade Initiative) the ASC is an independent not for profit organisation with global influence. ASC aims to be the world’s leading certification and labelling programme for responsibly farmed seafood.

The ASC consumer label demonstrates the integrity of the seafood product.

Global Aquaculture Alliance Best Aquaculture Practice (GAA BAP)

GAA BAP has been certifying aquaculture since 2004, and is administered by the GAA, a nonprofit organization dedicated to advocacy, education and leadership in responsible aquaculture. Aquaculture Facility Certification:

The BAP program employs a star system to signify the integration levels of BAP certification along the aquaculture production chain. These stars are displayed on the BAP logo and appear on packaging for a variety of farmed seafood products worldwide.


GG offers 16 standards for 3 scopes: Crops, Livestock, and Aquaculture. GG has been one of the most widely accepted private sector food safety certification in the world since 2007.

GG Aquaculture certified producers have now the option to use the consumer facing  GGN Certified Aquaculture label.

Friend of the Sea (FoS)

FoS is a non-profit NGO, whose mission is the conservation of the marine habitat. FoS is now a leading international certification project for products originated from both sustainable fisheries and aquaculture:

EU Organic Aquaculture

All aquaculture products sold as “organic” in the European Union (EU) have to fulfil the requirements that are laid down by the EU regulations:

This includes products certified according to private organic standards. The EU Organic logo makes organic products easily identifiable by consumers.


Naturland was founded in 1982 when organic agriculture was regarded as a marginal issue. Since the mid-1990s, Naturland has developed standards for different species and production systems in aquaculture:

The Naturland label is intended as a guide for consumers.

Soil Association

The Soil Association was formed in 1946 and champions organic principles and practice.

The Soil Association logo sends a message to consumers that the product is organically produced.

Indicates the Certification Scheme addresses the Key Consideration

 – Indicates the Certification Scheme has had one or more of its Standards benchmarked against the Global Benchmark Tool Version 1 and recognised by the GSSI Steering Board

Certified Aquaculture Production
Production of certified seafood, both aquaculture and wild catch, has grown rapidly over the past decade and now represents a significant portion of global seafood production. Certified sustainable seafood in 2003 equated to some 500,000 tonnes (0.5% of global production); in 2015 this figure had risen to 23 million tonnes (14% of global production). Some 80% of certified seafood is wild catch, but certified aquaculture is growing twice as fast and is set to dominate growth in certified seafood for the foreseeable future3.

In 2015, certified aquaculture accounted for 6.3% of world aquaculture production. Of this 6.3%, seven species groups were dominant (i.e. salmon, pangasius, mussels, tilapia, prawns, trout and sea bream) and accounted for 97%3. This relatively low global level of certified aquaculture and the narrow range of species groups, is largely due to:

  • China’s dominance in global aquaculture but its relative absence in certified production
  • 70% of all global production coming from small-scale producers

Certification of small-scale aquaculture continues to be an issue, mainly due to the cost and difficulties in complying with standards; key challenges include finance, technical knowledge and organisational capacity. Educating small-scale farmers on how to comply, as well as identifying national policy and regulatory gaps supporting small-scale aquaculture certification, is becoming ever more necessary6. Multiple-farm or ‘cluster’ certification may be a way forward for small-scale producers.

Four schemes are responsible for the majority of certified aquaculture production, namely the Aquaculture Stewardship Council (ASC), Global Aquaculture Alliance Best Aquaculture Practice (GAA BAP), GlobalG.A.P. (GG), and Friend of the Sea (FoS)3.

Certified Salmon Production
In 2015, the largest single source of certified aquaculture was salmon and it accounted for 56% of certified aquaculture globally3.

Figures provided by the certification schemes themselves and relating to their totals of certified farmed salmon break down into:

  • At least 1,461,761 tonnes of Atlantic salmon under GG (as of April 2019)7
  • 956,081 tonnes of ‘salmon, steelhead and trout’ under the GAA BAP Farm Standard (as of June 2019)8
  • 979,315 tonnes of ‘salmon’ under ASC (as of July 2019)9
  • 164,000 tonnes of ‘salmon’ under FoS (as of June 2019)10

(It is important to note that certification under one scheme does not preclude certification under another, and gathering accurate data on rates of multiple certification is very difficult. As a result simply adding the production volumes of individual schemes can result in double counting and overestimation. The authors of the aggregate data referred to above make no adjustment for multiple certification.)

  1. GSSI (
  2. Vince, J. and Haward, M., 2017. Hybrid governance of aquaculture: Opportunities and challenges. Journal of Environmental Management 201, (2017) p138-144
  3. International Institute for Sustainable Development (IISD), 2016. State of Sustainability Initiatives Review: Standards and the Blue Economy’ 2016. International Institute for Sustainable Development (
  4. SSC (
  5. SSC Guidance Voluntary Codes of Conduct (
  6. FAO (
  7. GG, pers. comm., 2019
  8. GAA BAP, pers. comm., 2019
  9. ASC (
  10. FoS, pers. comm., 2019