Frequently Asked Questions

What is aquaculture?

Aquaculture is the farming of aquatic species for human consumption and use. Aquaculturists, or aquatic farmers, grow finfish, shellfish, aquatic plants, and other organisms. Seafood can be grown in rivers, the ocean (marine systems) in suspended cages, on vertical lines, along the ocean floor, or on land (recirculating systems) in tanks. Aquaculture is not a new practice, in fact, historians believe fish were cultivated in China as early as 2000-1000 BCE [1]. Today, aquaculture provides over 50 percent of the world’s seafood supply [2], a figure which is expected to reach 63 percent by the year 2030 [3].

Why not just eat wild fish?

Global wild fisheries production has remained stagnant since the late 1980s, and is expected to decline over the next decade due to overfishing [3]. With a growing world population, we are challenged to support and develop productive, sustainable food systems. Seafood has the lowest feed conversion ratio of all animal protein (except for insects), requiring only 1.1 lbs of feed to produce 1 lb of body mass [4]. Environmentally responsible aquaculture is an important tool to fight food insecurity while managing the Earth’s natural resources for future generations.

Is farmed fish as healthy as wild?

Farmed seafood is safe and healthy to eat. The United States Food and Drug Administration (FDA) holds all seafood (domestic, imported, wild, and farmed) to the same food safety standards [5]. Research has shown that farmed fish can offer the same nutritional value and health benefits as wild fish [6]. Some blind taste tests for salmon have revealed that individuals actually prefer the flavor of farmed fish over wild-caught [7].

Are farmed fish treated with antibiotics/growth hormones?

Diseases and parasites are naturally present in the ocean as well as lakes and rivers around the world. Aquatic farmers need to engage in proactive health management to prevent illness from spreading from the wild to farmed fish. Such measures include reducing stress on the fish (related to overcrowding, temperature change, salinity change, etc.), vaccinating juvenile fish, site rotation, and reducing human handling. In many instances, the development of such practices has negated the need for antibiotic use, such as the case with Maine’s salmon farming industry [8]. Growth hormones are never used in U.S. aquaculture operations [9].

Do farmed fish have higher or lower levels of mercury/PCBs?

The risk of consuming pollutants (e.g. mercury, polychlorinated biphenyl (PCB), etc.) from farmed and wild seafood is about the same, and most products in the U.S. fall below FDA approved levels. These toxins “bioaccumulate” in fatty tissues, and tend to be more prevalent among larger, older fish (ex. tuna, swordfish, grouper, etc.). Those concerned with consuming such toxins, pregnant women in particular, shouldn’t avoid seafood altogether but should opt for species with very low concentrations (ex. salmon, mussels, scallops, clams, shrimp, crab, lobster, and groundfish including haddock, hake, pollock, and cod) [10]. These fish offer a good source of omega 3 fatty acids, vitamins, minerals, and protein without the high levels of toxins found in other species. Some individuals opt for farm-raised seafood in lieu of wild because they are raised in a controlled environment (water and feed are tested for toxins), and the products are often much more traceable than wild-caught seafood.

Is shellfish farming more sustainable than finfish farming?

Many people perceive finfish farming as having a greater environmental impact than shellfish farming. This is partly due to the fact that shellfish don’t require feed (they get their food from the ocean) and provide the key ecosystem service of water filtration. It is true that salmon add nutrients to the water in the form of uneaten feed and feces. If a farm is not managed properly, this can lead to eutrophication, an excess of nutrients in the environment. In extreme cases, eutrophication may contribute to algal blooms, which can deplete aquatic oxygen and cause fish kills. Because eutrophication is harmful to both wild and farmed fish, many farmers rotate their pens and allow sites to lay fallow for nutrient cycling and ecological restoration. It is in the best interest of aquatic farmers to maintain a high water quality in order to grow the healthiest, best product for market.

Every aquaculture operation is different, and environmental impact varies greatly between operations. In the United States all finfish farms must comply with a Clean Water Act Permit. That permit ensures that the farm does not have any negative impacts beyond its borders and that water quality is protected both on and off the farm. Another way to ensure you are purchasing seafood that was produced in the most sustainable way possible is third party certifications. These programs audit farms and require them to achieve a set of environmental standards based on the best science and available technology. Look for the blue label that says “Best Aquaculture Practices” when shopping for seafood. For more info, please visit​.

What makes salmon pink? Do they put dyes in the feed?

Salmon flesh is naturally pink. In wild salmon, this is in part due to the ingestion of carotenoids (the same pigment that gives carrots and sweet potatoes their color), which are produced by plankton and travel up the food chain. Different types of salmon around the world have varying degrees of color. For example, sockeye salmon’s famous deep red hue is the result of a biological difference which allows them to metabolize carotenoids more efficiently than other species like Atlantic salmon. Carotenoids, such as astaxanthin, an antioxidant that many people take as a supplement from health food stores, are added to salmon feed as a vital nutrient for fish health and growth and give farm-raised salmon its pink color. In Maine, salmon farmers are not legally allowed to add excess nutrients to the feed to change the color of their flesh; they can only add what’s required to keep the fish healthy.

What impact does aquaculture have on tourism and other coastal uses?

Research has not identified aquaculture as having a significant impact on coastal recreation, tourism, or other activities. In some cases aquatic farms serve as novel attractions for tourism companies [11]. Some stakeholders share a concern that working waterfronts can create diminished esthetic value, negative environmental impacts, and increased competition for space [12]. However, current practice in the U.S. is to choose site locations based on a number of important criteria, including protecting the environment , and a lack of conflict with transportation routes, recreation and tourism, and existing fisheries. Some states are looking into the development of offshore aquaculture operations to decrease pressure on crowded coastal waters [13].

For more information on marine aquaculture in the U.S., check out this fact sheet from the National Aquaculture Association, published in Aquaculture Magazine in 2021.

A Closer Look: Aquaculture in Maine

What types of seafood are farmed in Maine?

Maine is home to a variety of aquatic farms. As of 2019, Maine farmers raised Atlantic salmon, eastern oysters, blue mussels, different species of seaweed, scallops, soft shell clams, razor clams, surf clams, rainbow trout, brown trout, brook trout, halibut (experimentally), and green sea urchins (experimentally). While many of these species are relatively new, farmers have been raising oysters, mussels and salmon in the Gulf of Maine since the 1970s. The aquaculture industry in Maine has continued to grow and diversify, especially in recent years.

How big is Maine’s aquaculture industry?

In 2014, Maine had 107 aquaculture business entities in operation, which generated $73.4 million in output, $35.7 million in labor income, and provided 571 jobs [14]. The industry provides a statewide economic impact of $136.7 million in output, $56.1 million in labor income, and 1,078 full- and part-time jobs [14]. The state of Maine has seen steady growth in this industry. Since 2007, the total economic impact of aquaculture has nearly tripled from $50 to $137 million [14]. However, these figures are likely conservative due to survey response rates and biases. The Maine Department of Marine Resources reported the 2018 total harvest value of Maine-grown seafood alone to be roughly $72 million [15].

How much of Maine’s coastal waters is used for aquaculture?

In 2018, there were 190 individual aquatic farms in Maine operated by lease holders, and 200 pre-revenue operations. The total number of acres of coastal waters designated for aquaculture in Maine grew from 1,319 in 2018 to 1,558 in 2019 (less than the size of Rockland Harbor).

How regulated is Maine’s aquaculture industry?

Maine’s aquatic farmers are regulated by seven federal and five state agencies. The Maine Department of Marine Resources manages the state’s aquaculture leases. Applying for a lease is a rigorous process, and includes multiple public meetings including public hearings, pre-hearing meetings, notification of local landowners within 1,000 feet of a proposed site, marking of the proposed lease area, and on-site inspections to determine any possible effects on commercially and ecologically significant species, traditional fisheries, the ecosystem and all other uses [16].

There are a number of key regulations regarding aquaculture leases, including 1) leases may not exceed a term of 20 years, 2) no single lease may exceed 100 acres in size, no individual may lease more than 500 acres in aggregate, 3) applicants must report the ecological impact of the project and any adverse effects on existing uses of the area, as defined by the DMR [16], and more. Further, limited-purpose aquaculture (LPA) leases may not exceed 400 square feet of area, and no individual may hold more than four LPAs at once [17]. For more information on Maine’s aquaculture laws and regulations, please visit the DMR ​website​.

What role does climate change play in Maine’s aquaculture industry?

Maine’s sea farmers rely on clean water and healthy ecosystems to grow their products. They are very concerned about climate change, rising sea levels, ocean acidification, pollution from agricultural runoff and plastic waste, and other environmental challenges. Many farmers and the Maine Aquaculture Association (MAA) have lobbied for tougher regulations on pollution to protect Maine’s water quality, as well as climate change action at the state and federal levels [18].

MAA has seen a recent increase in the number of commercial fishermen participating in aquaculture. Some lobstermen have cited climate change and increasing pressures on the fishery as reasons for this, and others simply want to diversify their income. Aquaculture provides options for different species to be grown and sold in Maine, diversifying the coastal economy and helping communities become more resilient in the face of a changing climate.

Why is aquaculture an important sector in Maine?

Maine’s marine economy was once very diverse, with many thriving fisheries including groundfish like cod, flounder, hake, skate, and more. Today, Maine’s fisheries have converged to one primary species: the American lobster. While Maine’s lobster fishery is remarkably well-managed, the industry is threatened by changing ocean temperatures, acidification and pollution, and increased pressures on fishermen including rising bait prices and whale protection regulations. Further, the current moratorium on commercial fishing licenses presents a waiting period of up to 10 years for prospective captains. This has made it challenging for young people to start businesses on the water. With the oldest workforce in the country, and more young people leaving the state in search of jobs, Maine is challenged to create new job opportunities for young people.

Aquaculture offers a way for young people to work on the water while also diversifying the state’s marine economy. The industry may help mitigate environmental and economic issues by providing jobs and keeping working waterfronts alive in Maine, ensuring that future generations may continue to access and make a living on the water.


[1] H. Rabanal, History of Aquaculture. Rome: Food and Agriculture Organization of the United Nations, 1988.

[2] NOAA, “Aquaculture,” 19-Apr-2019. [Online]. Available: /topic/aquaculture. [Accessed: 26-Jul-2019].

[3] T. W. Bank, “Fish to 2030 : prospects for fisheries and aquaculture,” The World Bank, 83177, Dec. 2013.

[4] “How To Farm a Better Fish,” National Geographic. [Online]. Available: [Accessed: 26-Jul-2019].

[5] C. for F. S. and A. Nutrition, “Aquacultured Seafood,” FDA, Apr. 2019.

[6] K. Bacher, “Perceptions and misconceptions of aquaculture: a global overview,” p. 43.

[7] F. Asche and A. G. Guttormsen, “Seafood Markets and Aquaculture Production: Special Issue Introduction,” Mar. Resour. Econ., vol. 29, no. 4, pp. 301–304, Dec. 2014.

[8] “Maine Seafood Guide – Salmon – Maine Sea Grant – University of Maine,” Maine Sea Grant.

[9] N. Fisheries, “Feeds for Aquaculture | NOAA Fisheries,” 31-Oct-2018. [Online]. Available: /insight/feeds-aquaculture. [Accessed: 02-Aug-2019].

[10] Maine CDC, “The Maine Family Fish Guide: Advice from the Maine Center for Disease Control and Prevention,” Augusta, Maine, 2019.

[11] “Governors Task Force On The Planning And Development Of Marine Aquaculture In Maine,” Report and Recommendations, Jan. 2004.

[12] G. Murray and L. D’Anna, “Seeing shellfish from the seashore: The importance of values and place in perceptions of aquaculture and marine social–ecological system interactions,” Mar. Policy, vol. 62, pp. 125–133, Dec. 2015.

[13] S. Lester et al., “Marine spatial planning makes room for offshore aquaculture in crowded coastal waters,” Nat. Commun., 2018.

[14] A. Cole, A. Langston, and C. Davis, “Maine Aquaculture Economic Impact Report – Aquaculture Research Institute – University of Maine,” Aquaculture Research Institute, University of Maine.

[15] “Aquaculture Harvest Data: Maine Department of Marine Resources.” [Online]. Available: [Accessed: 05-Aug-2019].

[16] “Title 12, §6072: Research and aquaculture leases.” [Online]. Available: [Accessed: 05-Aug-2019].

[17] “Title 12, §6072-C: Limited-purpose aquaculture license.” [Online]. Available: [Accessed: 05-Aug-2019].

[18] “Maine oyster farmer stares down climate change, learns to adapt « Global Aquaculture Advocate,” Global Aquaculture Alliance. [Online]. Available: [Accessed: 05-Aug-2019].