Essentially 100% of the Atlantic salmon found in the market comes from farmed sources as historical commercial fisheries for wild stocks have ceased. Atlantic salmon is farmed around the world, primarily in net pens and cages in protected open water bays and increasingly in land-based closed-containment aquaculture systems. In many cases, Atlantic salmon takes on the name of the country where it was farmed, i.e. 'Norwegian salmon.' Atlantic salmon should have bright silver skin and with its black cross spottings, it closely resembles coho salmon. The flavor is milder than wild salmon and the flesh coloration ranges from a deep orange to a pinkish-orange and this variation comes from different types of feed in the different farms. When raw, the meat almost looks marbled and when cooked the large moist flakes retain the raw color of the flesh.
Key sustainability sourcing notes for Atlantic salmon based on landings data from 2014-2015 and the most recent 2014-2017 Seafood Watch assessments and current ASC certifications:
~25% of global farmed Atlantic salmon production is certified to the standards of the Aquaculture Stewardship Council (and is now recognized by Seafood Watch eco-certification as at least equivalent to a "Good Alternative (yellow)" recommendation) Norway produces ~55% of global farmed Atlantic salmon and ~50% of global ASC-certified Atlantic salmon Chile produces ~25% of global farmed Atlantic salmon and ~30% of global ASC-certified Atlantic salmon ~3.5% of global farmed salmon production comes from British Columbia and meets a Seafood Watch "Good Alternative (yellow)" recommendation From 2012 to 2015 global farmed salmon production has increased ~15%
Atlantic salmon have an elongated, spindle-shaped body that is broad in the middle and tapers off at the ends. Juveniles have between eight and 12 blue-violet “parr” marks – stripes with little red spots in between. Adults have bluish-green dorsal spots, silver sides, and white bellies. During spawning, adults will become a dark brown, yellow, or bronze color and males will develop an elongated hooked jaw. Males may also develop a red coloration or develop black patches during this time. Adults are generally 28 to 30 inches in length and weigh between eight to 12 pounds though some individuals can reach up to 30 pounds.
All Atlantic salmon begin life in freshwater streams or rivers. Females lay an average of 7,500 eggs in gravel nests called “redds.” Eggs incubate slowly over an extended period of time, with only about nine to 20 percent of the eggs surviving to the “fry” stage. Fry remain buried for about six weeks and emerge from their redds around mid-May. Once fry disperse from their redds they enter their “parr” stage where they develop their blue-violet camouflage stripes. Parr can remain in freshwater rivers and streams anywhere between one and five years where they prefer shallow, cold, fast-flowing water and will feed on invertebrates, terrestrial insects, and even small fish. Eventually the parrs enter a physiological process called “smoltification” that prepares them for marine life. Upon entering this phase, the “smolts” will migrate downstream and enter the ocean where they are pelagic, will undergo the majority of their physical growth, and conduct extensive feeding migrations. During this time, juveniles will feed on krill and amphipods. Both juveniles and adults feed on a variety of fishes – with adults feeding on herring, smelt, and small Atlantic mackerel as well as squid. Atlantic salmon are known to remain in their marine environments for up to four years. Once they reach maturation, Atlantic salmon will return to the natal freshwater streams or rivers of their birth – which have been imprinted on them during smoltification. Not all Atlantic salmon die after spawning and some fish, now referred to as “kelts,” return to the sea after spawning and will repeat the breeding cycle.
Birds, marine mammals, and a variety of different fish species prey on Atlantic salmon.
Atlantic salmon are the only salmon species native to the Atlantic Ocean. They are found on both the eastern (European) and western (North America) North Atlantic Ocean as well as around North Atlantic islands such as the United Kingdom, Iceland, Greenland, etc. There are three groups of wild Atlantic salmon – North American, European, and Baltic. The North American population historically ranged from Long Island Sound to northern Quebec and Newfoundland. Their US range has been considerably reduced and is currently limited to the state of Maine as a direct result of habitat destruction, dams, and historic overfishing. Landlocked populations occur in Russia, northern Europe, and North America. Additionally, Atlantic salmon have been introduced in other parts of the world outside of their native range. Atlantic salmon are anadromous and hatch and spend their early life stages in freshwater rivers and streams – eventually undergoing downstream migrations where they will enter the marine environment. Upon entering the ocean, Atlantic salmon will feed and grow and undertake extensive migrations. Like other salmon species, Atlantic salmon will return to the freshwater system of their birth to spawn; however, unlike other salmon species, not all will die after spawning with some individuals returning to the ocean and repeating the breeding cycle.
Science & Management
In 2007, NOAA and the USDA launched the Alternative Feeds Initiative, the purpose of which is to identify alternative ingredients to fishmeal and fish oil in aquaculture feeds while still maintaining the human health benefits of farmed seafood. The ultimate goal of this work is to commercialize these alternative ingredients in order to reduce dependence on marine fish by feed manufacturers and seafood farms - including salmon farming operations - on a global scale.
The Northwest Fisheries Science Center’s (NWFSC) Aquaculture Program has been conducting research into alternative feed ingredients. The program is currently investigating the option of combining plant protein ingredients with novel fish protein meals that are by-products of fish processing. Researchers at the NWFSC are also looking into the feasibility of using lipid sources in feed and determining nutrient requirements for fish fed plant protein alternatives. In addition, the NWFSC is exploring larval fish physiology and nutrition which will improve understanding of what the best diet for developing marine larvae might be. The Aquaculture Program is studying the physiological responses of larval marine fish when fed and how larvae utilize complex feed ingredients as well.
The NWFSC’s research also extends into the realm of genetics - this work can help improve the quantity and quality of fish production and increase knowledge on how fish grow, resist disease, and mature. The Southwest Fisheries Science Center uses genetics and genomics to study reproduction, larvae, life history of fish of brood stocks. NOAA Fisheries have developed the Offshore Mariculture Escapes Genetics Assessment (OMEGA) mathematical model which describes the potential effects aquaculture escapees can have on the survival and genetic fitness of wild fish populations. NOAA has conducted work to study nutrient impacts resulting from fish farming. In collaboration with academic partners and fishermen, NOAA grew steelhead trout using Integrated Multitrophic Aquaculture and found a net removal of nutrients from the water column occurs.
Norway is the world’s largest producer of farmed Atlantic salmon. In Norway, The Aquaculture Act (the Act) regulates the management, control, and development of both land-based and marine aquaculture. The Act is administered by The Ministry of Fisheries and Coastal Affairs and covers aquaculture of any aquatic organism throughout its entire production cycle (hatchery to broodstock). Within the Ministry, the Directorate of Fisheries is responsible for coordination, administration, surveillance, and enforcement of the aquaculture sector. The Act establishes a licensing system for aquaculture which is carried out by the Ministry. Under the Act, the Ministry can limit the number of available licenses, determine the geographic distribution of licenses, select applicants, and administer fees. Adopted under the Act, the Regulation relative to authorizations for the breeding of salmon, trout and rainbow trout (Salmon Allocation Decree) provides for the allocation of licenses for farming these particular species. The Act creates a maximum stocking density (relative to the carrying capacity) for each site, establishes minimum distances between sites, and requires a 60-day fallowing between each production cycle.
In Chile, the world’s second largest producer of Atlantic salmon, aquaculture is regulated by the General Law of Fisheries and Aquaculture. There are numerous government agencies involved to some degree in aquaculture regulation in Chile. Among these include:
Undersecretariat of Fisheries and Aquaculture (Subpesca) – which regulates aquaculture activities and establishes the technical conditions for its development;
Undersecretariat for the Armed Force – which grants licenses and establishes appropriate areas for aquaculture production;
Environmental Assessment Service – which participates in the environmental evaluation of projects;
General Directorate of Maritime Territory (DIRECTEMAR) – which works to monitor activities developed in waterways; and,
National Fisheries and Aquaculture Service (Sernapesca) – which monitors compliance with the norms of aquaculture, sanitary management, and provides services to enable their correct implementation.
Sernapesca manages prevention and surveillance programs for high-risk diseases as well as manages site grouping. They also provide an annual fish health report, provide data on disease and sea lice (as well as listing centers of high sea lice concentrations), and provide data on mortality by species and region, categorized by disease type. Sernapesca also produces an annual report on chemical use which contains resources on antibiotic use by species, the types and quantities of antibiotics used, use by region, and as of 2015, total use by each company operating in Chile. The key environmental regulation in Chile is Reglamento Ambiental para la Acuicultura (RAMA). Under RAMA, Sernapesca preforms benthic, seabed habitat assessments for INFA (Informes Sanitarios y Ambientales Acuicultura) prior to harvesting. These site-level assessments, along with mortality numbers and other performance parameters, are used to predict stocking numbers and contribute to setting multi-site biomass and stocking limits for salmon farms operating in Chile.
Numerous local, state, and federal agencies are involved to some degree in the permitting process and regulation of Atlantic salmon aquaculture in the United States. While there is no national oversight agency for aquaculture in the US, there are extensive regulations in place regarding predator controls, therapeutant use, and disease management. Permitting varies by location with numerous federal agencies providing some degree of oversight. These include:
The United States Department of Agriculture (USDA) – which is responsible for coordinating national aquaculture policy and providing industry with research, information, and extension services;
The Environmental Protection Agency (EPA) – which regulates waste discharge from aquaculture facilities;
The Fisheries and Wildlife Service (FWS) – which regulates the introduction and transport of fish; and,
The Food and Drug Administration (FDA) – the FDA’s Center for Veterinary Medicine is responsible for approving and monitoring the use of drugs and medicated feeds used in the aquaculture industry.
Additionally, the National Oceanic and Atmospheric Administration (NOAA), the US Coast Guard, the Bureau of Ocean Energy Management (BOEM), and the US Army Corps of Engineers are involved in the permitting and management of Atlantic salmon aquaculture. Amongst regulations, US salmon farms must adhere to include the Magnuson Stevens Fishery Conservation and Management Act, the Endangered Species Act, the Clean Water Act, and the National Environmental Policy Act.
NOAA Fisheries, the US FWS, and the New England Fishery Management Council manage wild populations of Atlantic salmon under the Fishery Management Plan (FMP) for Atlantic Salmon. There is no wild commercial Atlantic salmon fishery in the US and the FMP prohibits possession of any Atlantic salmon in federal waters –regardless if directly or indirectly caught. All wild-caught Atlantic salmon must be immediately returned to the water in a manner that best ensures their survival. In 2000, NOAA and the US FWS listed the Gulf of Maine salmon population as Endangered, under the Endangered Species Act. In 2009 this designation was extended to salmon in the Penobscot, Kennebec, and Androscoggin rivers and tributaries. These protections extend outside of these locations to wherever the fish are found.
Data availability for recirculating aquaculture systems (RAS) worldwide is good. Categories such as effluents, locations and habitats, escapes, source of stock and energy use are thoroughly studied and available to the public. However, certain information pertaining to RAS, such as production statistics and feed formulations, are not as readily available and given that these systems are a fairly new development, long-term scientific data may not be available either. Salmon brands such as Verlasso®, Blue Circle Foods®, and Sixty South also have good data availability and quality. In addition, Seafood Watch considers data quality and availability for marine net pen salmon farming in Norway, Canada (both in British Columbia and on the Atlantic coast), Scotland, and Maine to be good. Data for Chile’s salmon farming is considered average as certain environmental impacts are typically less transparent, making some aspects of the industry poorly understood, though data availability continues to improve in the country.
Land-based closed containment recirculating aquaculture systems (RAS) use small total water volumes when compared to other aquaculture product systems and because of this have only small volumes of effluent generated and discharged from facilities. This type of production system also allows for all waste materials, including sludge and wastewater, to be collected and treated on site prior to discharge. These materials are treated and can then be disposed of via municipal wastewater treatment plants, land application, or compost production. While post-treatment wastewater from some RAS facilities is discharged into local water bodies, all facilities require a permit to do so, which is regulated and monitored on a regular basis under regional regulations.
On the other hand, marine net pen farming allows for large amounts of effluent to be discarded into waterways. Waste nitrogen, phosphorus, and organic matter account for large parts of effluent released into the water. Impacts of these effluents, such as changes to nutrient ratios and microbial communities, are still being studied on an international scale to help improve understanding of the effects of salmon farming on local ecosystems. Some countries with net pens do regulate and monitor the waste, but even the highest Seafood Watch effluent scores for Scotland, British Columbia, and the largest salmon farm in Chile respectively, were moderate at best.
Recirculating aquaculture systems (RAS) can be built and operated virtually anywhere and can make use of existing buildings such as warehouses and greenhouses. Many RAS systems when built, are done so on previously converted land so there is no new habitat conversion or loss of ecosystem functionality during a new facility’s set-up. These systems are also closed and contained, which means there is very little interaction with local habitats.
Though open systems have little impact on the physical nature of habitats, they can have a significant negative impact on local habitats as a result of discharge and deposition of feed and fish waste. These impacts tend to vary by country and by farm. In Norway, net pen salmon farms produce substantial nutrient pollution, but recent data indicated a low risk to local benthic habitats near the farm areas, with little organic loading. Floating net pens in Scotland and British Columbia received moderate scores because the habitat impacts are reversible and impact relatively small areas.
Floating net pens at the largest salmon farm in Chile can lead to conditions of high waste deposition in the fjord region where it operates - this region has a high global conservation priority. But Seafood Watch has found that conditions can return to normal when fallowing occurs before restocking. Elsewhere in Chile, the seabed impacts from floating net pens can be severe. The industry there is also rapidly expanding into pristine areas and more research is needed in these high-value conservation areas.
The feed formulations used for Atlantic salmon farming vary greatly, with some making use of fishmeal and fish oil from wild sources such as farms in North America. Chile’s largest salmon farm uses feed made from genetically-modified yeast instead of protein from wild fish and the farm has been testing an algal-based feed ingredient as well. Elsewhere in Chile, and also in British Columbia and Scotland, farms are increasingly replacing fishmeal and fish oil with alternative crop proteins and oil ingredients, and in some cases with by-products from land-animal processing. Norwegian salmon farmers have also made progress in reducing wild fish for feed, now including byproducts from terrestrial crop sources in particular.
Source of Stock
Globally, the Atlantic salmon farming industry uses domestic broodstock and hatcheries, keeping sourcing independent from wild salmon populations, according to Seafood Watch.
Disease, Pathogen and Parasite Interaction
Land-based recirculating aquaculture systems (RAS) allow for greater control over the farming environment than open net pens. Sterilization of incoming waters, alongside strict biosecurity protocols, helps to reduce the risk of diseases being introduced into RAS. In addition, the treatment of effluents limits the number of pathogens and diseases that can be transmitted to wild populations. Though disease outbreaks have occurred in RAS, this is mainly attributed to improper implementation of quarantine procedures.
In British Columbia, research has highlighted the potential impacts of pathogens and parasites on wild salmon populations and there is concern regarding the transfer of sea lice from farms. Dominant diseases in Chilean salmon farms include salmon rickettsial syndrome (SRS) and parasitic sea louse. Though there is potential for transmission to wild fish, there is little evidence these diseases are affecting wild populations. North Atlantic salmon farms contend with bacterial kidney diseases, sea lice, and skin lesions in farmed populations. Infectious Salmon Anemia (ISA) has also been an issue for salmon farms in this region, but once again there is little evidence of transfer to wild populations.
Parasitic sea lice numbers from Scottish Atlantic salmon farms have been increasing in recent years and elevated levels of this parasite have been found in the environment around farms, despite the use of pesticides. The government has acknowledged the fact that the elevated levels of sea lice have the potential to kill fish in the vicinity of these farming operations, but there is no significant evidence of population-wide impacts.
According to Seafood Watch, viral diseases and sea lice are a top concern for Norwegian salmon farms. Based on results from the national sea lice monitoring program, the Norwegian Institute for Nature Research and the Norwegian Veterinary Institute both agree that there is evidence of population-level impacts on salmon populations in certain regions. Sea lice has been highlighted as a threat to wild salmon to the degree that they can cause reduction to wild populations. In Norway, brown trout has also been identified as a species that can be affected by sea lice transmission from salmon farms.
Escapes and Introduced Species
Land-based recirculating aquaculture systems (RAS) for Atlantic salmon farming tend to be enclosed in secure buildings and tanks, reducing the risk of escapes. Tank-based RAS have screens, along with water treatment and secondary capture devices which further minimize the chance of escapes. On the other hand, salmon farms that utilize net pens pose a much higher risk of escape since they are located offshore.
Chile’s largest salmon farm uses best management practices that exceed national standards to prevent escapes. However, large escape events continue to occur in Chile - for example, almost 800,000 fish escaped in one event in 2013 - but they are occurring less and less. Seafood Watch also noted that escaped farmed Atlantic salmon are unlikely to become established in the wild in Chile, especially as they have been shown to be a poor colonizer in that region (Atlantic salmon is a non-native species in Chile).
Tens of thousands of salmon have escaped from farms in Scotland with very few recaptured. Seafood Watch reported that these escapes have impacted wild populations - studies show evidence of farmed genetic material already present in Scotland’s wild salmon. This is a cause for concern with regard to genetic fitness of native salmon populations. Norwegian farms have also reported large escape events. Escape events of about 50,000 farmed salmon have occurred in six out of the past seven years. Improved management and pen design have reduced the number of escapes, but previous events have already had negative effects on wild salmon populations.
Salmon farms operating in North America’s Atlantic regions must abide by the Code of Containment protocols that include requirements for siting, system design, materials’ strength, maintenance and inspection, stock loss and recovery and best practices for fish handling procedures that are meant to reduce the risk of escape. Maine farms have not reported a breach since 2003, though escapes do still occur in Canada.
Escape numbers have varied in British Columbia over the past several years, ranging from a dozen to more than 100,000, although last year’s annual maximum of escapees reported was only 22. Seafood Watch concluded that there is no evidence for a high presence of farm escapees in wild populations in British Columbia, though the potential for escapes resulting from human error or inclement weather is still of concern.