With wild-fish stocks falling, a huge increase in farmed fish will be needed to meet the protein needs of the planet. James Richens reports on how the search for sustainable sources is focusing on the deep oceans, on land and even the laboratory
Aquaculture, the farming of aquatic animals and plants in the sea or inland waters, has a crucial role in meeting the challenge of how to feed a growing population while reducing the environmental impacts of food production, experts say. It can also create jobs and improve security of food supplies at a time of great economic uncertainty due to the coronavirus pandemic.
From 1990 to 2018 there was a 527% rise in global aquaculture production, according to data from the Food and Agriculture Organization (FAO) published in June. In contrast, production from wild-capture fisheries increased by only 14% over the same period.
In 2016, aquaculture overtook fisheries as the main source of fish for human consumption, and accounted for 52% of global production in 2018. The FAO forecasts that aquaculture’s share of production will increase to 59% (109 million tonnes) by 2030.
There is growing evidence that marine aquaculture has substantial potential to produce food sustainably
There are many sustainability benefits driving the growth in aquaculture. Fish is less resource-intensive to farm and has a lower carbon footprint than meat, but with only 65.8% of wild-fish stocks at biologically sustainable levels, according to the FAO, down from 90% in 1974, aquaculture will be needed to make up the shortfall.
Over 20 million people are employed in aquaculture, according to the FAO, with the majority in small-scale activities in developing countries.
Marine aquaculture – also known as mariculture – offers most potential for growth, according to a recent report for the High Level Panel for a Sustainable Ocean Economy, a group of 14 heads of government from countries such as Canada, Norway and Japan. It says that the ocean is an under-used resource, as almost 63% of existing aquaculture is in freshwater areas such as lakes and rivers, where space and the variety of farmed species is limited.
The ocean could supply over six times more food than it does today, the report says, reaching 364 million tonnes of animal protein and more than two-thirds of the edible meat that will be needed to feed the future global population, which the UN expects to reach 9.8 billion by 2050.
"There is a growing body of evidence that marine aquaculture has substantial potential to produce food, and do so sustainably,” says one of the report’s authors, Dr Halley Froehlich, assistant professor at the University of Santa Barbara, California. “However, whether that full potential is realised still depends on factors such as demand shifts, and clear policies that not only regulate but support mariculture, using best practices," she adds.
Mariculture could supply both unfed seafood such as mussels and seaweed, which take their nutrition from the water, and fed mariculture such as salmon and prawns, which need feed inputs. On the face of it, unfed mariculture offers the greatest potential for growth since its input requirements are much lower. But consumer preference has favoured fed mariculture, the report says, and a major limiting factor is where the feed comes from.
We’re talking about millions of tonnes of fish being taken out of the ocean. People in west Africa don’t have that fish to spare
In the wild, fish species such as salmon eat a variety of food, including smaller fish. When farmed they are fed fishmeal and fish oil, which contain essential nutrients derived from other fish, in particular omega-3 fatty acids. Around 18% of wild-caught fish – mainly forage fish such as anchovy, sardine and herring – are processed into fish feed.
This practice has been strongly criticised by campaign groups, who argue that these fish are an important source of food for people living in poor coastal communities. A report by Changing Markets Foundation in 2019 accused fish-feed producers, the aquaculture industry and supermarket retailers of “stripping the oceans bare” to meet demand for popular farmed fish products such as salmon and prawns.
“We’re talking about millions of tonnes of fish being taken out of the ocean every year,” says Natasha Hurley, campaign manager at Changing Markets Foundation. “People in west Africa don’t have that fish to spare.”
The aquaculture industry has greatly reduced the proportion of feed derived from wild-caught fish by switching to fish by-products as well as plant-based alternatives. For example, fishmeal and fish oil inclusion rates in the diets of salmon farmed in Norway have dropped from 29% and 24% respectively in 2000 to 15% and 8% respectively in 2018, according to data from the Marine Ingredients Organisation (IFFO).
However, switching to alternative feeds may not be sustainable if they come from sources such as soy, which can contribute to other environmental problems such as deforestation. It is also important that they provide the nutrients that farmed fish need. Some companies are looking at innovative options such as industrial fermentation.
Veramaris is a joint venture formed in 2018 by Dutch-based biotechnology company DSM and German chemicals firm Evonik. In July 2019, the partnership opened a $200m manufacturing site in the US state of Nebraska, which will supply 15% of the global omega-3 fatty acid demand for salmon aquaculture, the equivalent of over one million tonnes of wild-caught fish.
We would like to go offshore because that is the natural habitat of the salmon
The process works by fermenting marine micro-algae with sugar from beet, wheat or corn to make an oil that contains omega-3 fatty acids at a 50% concentration.
Consumer-facing businesses with reputations at risk have an important role in driving the switch to sustainably farmed fish. UK supermarket chain Tesco has been working with its key salmon suppliers to scale up the use of more sustainable feed ingredients. One of its suppliers in Norway has started to supply salmon that was partially fed with omega-3 algal oil.
Mariculture faces other sustainability challenges that it must overcome to realise its potential to help feed the world. Most is done close to the coast for ease of access, but this means that fish farms can cause water pollution and degrade local ecosystems. Disease and parasite transmission between farmed and wild fish is also a major problem, as well as a commercial cost through fish mortality.
One solution being explored by Norwegian aquaculture company SalMar, one of the world’s largest producers of salmon, is to open sites much further offshore. In 2017 it launched a pilot aquaculture facility 22km off the coast of Norway in an area of sea called Frohavet. The facility, called Ocean Farm 1, has a production cycle capacity of 7,000 tonnes of salmon and cost 1bn Norwegian Kroner ($110m) to design and build.
Trine Sæther Romuld, chief financial and operating officer of SalMar says: “We would like to go offshore because that is the natural habitat of the salmon.” The deeper waters allow for optimal temperatures, currents and water quality for the fish to thrive and grow, she explains. However, operating in rough weather conditions also raises technical challenges. Ocean Farm 1, constructed by the China Shipbuilding Industry Corporation, can withstand waves 10 metres high.
A faster exchange of water in the pen compared with coastal locations is driven by natural ocean currents, keeping the water clean and reducing the risk of disease and parasites. Ocean Farm 1 has demonstrated a lower fish mortality rate than the average of just under 5% across SalMar’s operations in 2019.
You need to have an in-depth understanding of the design decisions that impact fish welfare and biosecurity
SalMar is planning a new facility called the Smart Fish Farm, which is double the capacity of Ocean Farm 1, and is due to commence operation in 2023/24. It will be located some 35km offshore and will be designed to withstand wave heights of over 30 metres.
Another innovative solution is to move the entire aquaculture operation out of the ocean and on to land. This is the approach of Nordic Aquafarms, which has been operating three land-based aquaculture farms with a total production capacity of 2,500–3,000 tonnes: a salmon farm in Norway, since 2019, and two yellowtail kingfish sites in Denmark, since 2017.
It is planning to build a site in the US state of Maine, which is due to start operations in 2024, and a further site in California. Each will produce some 33,000 tonnes of fish per harvest.
Erik Heim, president of Nordic Aquafarms, explains that the logic of locating land-based sites in the US is to get closer to its customers. At present, fresh salmon and kingfish is imported via airfreight; producing fish in the US will halve its carbon footprint. The US also has restrictive regulations on coastal developments that make conventional aquaculture difficult.
Land-based aquafarms use large tanks in which circulating water is constantly filtered and treated to provide optimum, bio-secure conditions for the fish. Effluent is treated before being discharged, minimising pollution. Energy use is the main impact, but Heim says
the grid electricity mix at the US sites has a good proportion of renewables. Because the fish swim constantly in the tanks, their meat has a lean and firm texture that attracts a premium price.
But despite these advantages, “it’s not just plug and play technology,” warns Heim. “You need to have an in-depth understanding of the design decisions that impact fish welfare and biosecurity, and experienced staff who really know their stuff.”
You have to pursue sustainable and responsible production whatever method you use
In such a highly controlled environment, human error or technical failure can result in a catastrophic loss of stock.
Seafood could even be gown in the laboratory without the need for water or even fish. Shiok Meats, founded in 2018 and based in Singapore, is developing technology to cultivate meat using stem-cells from crustaceans such as shrimp, crab and lobster. The cells are cultivated in a stainless steel tank that provides the right temperature, humidity and nutrients, becoming meat in fourto six weeks.
However, commercialisation of cell-based seafood seems some way off. At present, one kilogramme of lab-grown shrimp meat costs $5,000, although this could be cut to $50 by reducing the cost of the growing media. The company is raising $5m to build a pilot plant to scale up production. Shiok also needs to obtain approval for its products from food regulators.
Which of these solutions is leading the race towards sustainable aquaculture?
When you look at demand internationally, it's clear that we're going to need multiple methods, including wild-catch, to meet demand," says Heim, of Nordic Aquafarms. "You have to pursue sustainable and responsible production whatever method you use.”
James Richens is an experienced business journalist specialising in corporate sustainability, green finance and environmental policy. He was editor of The Economist Group's World Ocean Initiative, sustainability editor of The ENDS Report and research editor at Trucost, part S&P Global.
This article is part of our in-depth briefing, Sustainable oceans. See also:sustainable fisheries aquaculture FAO High Level Panel for a Sustainable Ocean Economy farmed salmon SalMar Veramaris Changing Markets Shiok Meats Nordic Aquafarms