Back to FISH Vol 28 3
PUBLISHED 1 Dec 2020

The sustainable production of meat proteins from the world’s oceans could almost double by 2050, according to a recently released international blue paper, The Future of Food from the Sea.

By Catherine Norwood

The report has identified that capture fisheries could increase yields by 20 per cent, and mariculture – or ocean aquaculture – has the potential to increase 600 per cent over the next 30 years.

With this, the oceans would be capable of sustainably providing up to two thirds of the estimated 470 million tonnes of animal protein that the anticipated global population of 9.1 billion would require.

The Future of Food from the Sea is one of 16 blue papers commissioned by the High Level Panel for a Sustainable Ocean Economy, and has a focus on how the oceans can address the United Nations (UN) Sustainable Development Goal 2: Zero hunger.

The High Level Panel is an initiative of 14 heads of government, including the Australian Prime Minister, committed to catalysing bold, pragmatic solutions for ocean health and wealth that support the Sustainable Development Goals.

The modelling used to provide production estimates and ‘sustainable supply curves’ account for ecological, economic, regulatory and technological constraints. These are overlaid with demand scenarios to estimate future seafood production.

The Future of Food from the Sea lead authors Christopher Costello, Ling Cao and Stefan Gelcich report current production from capture fisheries at 80 million tonnes, with 29 million tonnes from mariculture. Combined, these produce 58 million tonnes of edible meat foods. In the most optimistic scenario modelled, the authors suggest this could be increased to 364 million tonnes of food a year.

They highlight fisheries management as the key factor to limit growth of capture fisheries, while reliance on capture fisheries for critical feed ingredients is the major constraint for mariculture.

Competitive advantages

Food from the sea provides about 17 per cent of the current production of edible meat worldwide; however, demand for food is increasing. The paper highlights five areas where the oceans outshine their terrestrial counterparts when it comes to food production.

Climate change: Food from the ocean does not contribute to land use changes, such as forest clearing, that drive climate change. The harvest of wild fish and farming of marine animals also have lower greenhouse gas emissions per portion of protein than the farming of terrestrial animals.

Feed efficiency: Ocean animals are particularly efficient at converting feed into food for humans. Some mariculture species do not need feed inputs, and fed mariculture systems are more efficient than terrestrial systems.

Production potential: Unlike land-based food production, the suitable area for cultivating food from the sea is not limited by scarce land and water resources, although there are limited appropriate locations for mariculture.

Accessibility: Seafood is readily available to coastal communities and well situated for trading.

Nutrition: In addition to protein, seafood provides essential vitamins, minerals, long-chain omega-3 fatty acids and other nutrients not found in plant-sourced foods or other animal proteins.

The report considers a combination of improved harvests from capture fisheries along with mariculture. It identifies that the largest potential gains come from mariculture, which it breaks into two categories: unfed and fed.

Unfed mariculture includes species that can be farmed without the need for feed inputs, which are supplied by the oceans themselves, such as seaweeds and bivalves. While recognising the significant potential to increase the production of seaweeds as a food product, the report has not included them in its calculations.

Fed mariculture includes species for which feed must be provided, such as crustaceans and finfish. And while this sector represents the area of greatest gain, the report suggests its growth will be constrained by the continuing need for fish meal and fish oil in the diets of mariculture species.

Capture fisheries

The world’s capture fisheries extract about 80 million tonnes of fish from the sea each year, based on 2016 figures from the UN’s Food and Agriculture Organization (FAO). However, this is expected to decline to 67 million tonnes under a ‘business as usual’ scenario. Some fish stocks would decline as a result of overfishing; other stocks will remain underfished.

Yet with improved management to reduce overfishing and to increase the efficient harvesting of other stocks, including better use of underfished resources, the report estimates wild fisheries could increase production to 98 million tonnes a year, fishing to maximum sustainable yield. This is an increase of 20 per cent on current yields and 40 per cent on the potential decline under a continuation of current practices. However, the authors estimate 96 million tonnes as the economically viable sustainable yield, taking into account management costs and market prices for fish.

The report considers a combination of improved harvests from capture fisheries along with mariculture. It identifies that the largest potential gains come from mariculture, which it breaks into two categories: unfed and fed.

Recent research funded by the FRDC indicated Australia has significant underfished wild stocks, with the potential to more than double its harvest based on the 2016-17 catch if stocks were fished to their maximum sustainable yield. However, the total potential yield of 371,500 kilograms, as reported in FISH December 2019 ‘Doubling up on wild fisheries’, also shows the tiny contribution Australian wild fisheries make to the annual global total harvest – less than 0.4 tonnes of the 80 million tonnes produced each year.

The report indicates improved management is needed globally to address overfishing; illegal, unregulated and unreported fishing; and fishing subsidies, which encourage fishing that would otherwise be uneconomical.

Other issues that could also affect future harvests from wild fisheries include climate change, habitat degradation and pollution, and interaction with fed aquaculture as a feed source and as a competitor for coastal ocean resources.


Mariculture represented 36 per cent of total global marine animal production in 2016, or 29 million tonnes. Production of both unfed and fed species has increased in the past 20 years; however, demand has driven a significantly greater increase in the fed species, such as salmon, of 600 per cent, according to FAO figures for 2018.

Over half of mariculture production of marine animals is shelled molluscs, while finfish and crustaceans represented 23 per cent and 17 per cent, respectively, the report says. When these volumes are converted to edible food equivalents, finfish mariculture provides more food by volume than shelled molluscs and offers the potential for the greatest gains in food production.

Unfed mariculture

The report estimates bivalve production, as a form of unfed mariculture, could be increased from current levels of 15.3 million tonnes to 768 million tonnes, with about 60 per cent of this being profitable based on a market price for Blue Mussels of US$17,000 per tonne.

Production estimates are based on suitable marine habitat of 1.5 million square kilometres spanning temperate and tropical regions. The authors suggest prohibitive regulatory barriers, which may be driven by food safety concerns, as a major contributor to the gap between actual and potential production.

While seaweed mariculture provides 1.4 million metric tonnes (dry weight) of food a year, it has not been included in the report’s supply chain curve calculations. The report does recognise there is significant potential to expand production of a range of uses including food, and as a mariculture feed ingredient, reducing reliance on capture fisheries.

The expansion of unfed mariculture will be constrained by the limitations of the ecological carrying capacity of local environments, particularly under climate change.

Fed mariculture

If fed mariculture could be freed from the constraints of capture fisheries as a source of critical feed ingredients, the paper calculates the potential of finfish mariculture at 15 billion tonnes – more than 100 times the yield from capture fisheries.

But under current feeding regimes and requirements for fishmeal and fish oil ingredients, bivalves rather than finfish offer the greatest potential for increased production for mariculture as a whole.

A modelled scenario where fishmeal and fish oil demand are reduced by 75 per cent could double potential finfish production. But it increases sixfold when fish oil and fishmeal demand are reduced by 95 per cent, resulting in an estimated 180 million tonnes of edible meat protein. Economically viable production is based on a price of $US5000 per tonne; the global price for salmon is in the order of $US7000 per tonne, the report says.

Existing production systems rely on an estimated 18 per cent of the harvest from capture fisheries being used to produce fish meal and fish oil. The authors recognise trade-offs will be needed in sourcing alternative feed ingredients to support increased mariculture.

Advances in regulatory policies and ocean property rights, along with mariculture technologies, farming systems and genetic improvements in species farmed are also identified as important to grow the sector.

Mariculture production has the potential for negative environmental impact, such as disease and parasite outbreaks, chemical and nutrient pollution, and habitat loss.

Some can be addressed through technological advances, and at a cost that might make profitable operations unprofitable. Establishing and enforcing standards, pricing environmental externalities into production and financial incentives for research and development should all be considered.

Consumer trends

While the supply of food from the sea can expand significantly, demand for these products will depend on prices, consumer preferences, income and national and local capacities to implement novel management approaches.

Seafood consumption per capita has doubled since 1961 and is projected to continue rising, along with increases in population and affluence. International research indicates consumers do not see fish as an immediate substitute for terrestrial meats, and trends towards health-conscious diets have been shown to increase seafood consumption.

The quantity of a particular fish purchased in markets depends on income, prices and preferences, and the blue paper notes that forecasting preferences can be challenging, as once-rejected species find themselves in demand. Bluefin Tuna was once regularly discarded, halibut was thought to be unpalatable and jellyfish had a market limited to Asia.

Rebranding can also play a role. Slimeheads, as they are historically known in the US, were in high demand as Orange Roughy, and Patagonian Toothfish is marketed more successfully in some countries as Chilean Seabass. Likewise, Atlantic Salmon forged its way into traditional Japanese sushi markets, rebranding itself as a key ingredient even though it is not a traditional sushi species.
The blue paper highlights that significant expansion of food production from the ocean is costly.

Mariculture has much greater production potential than capture fisheries, but generating this production is expensive. Scaling up and intensifying mariculture, as terrestrial food production systems have been, will help reduce costs. However, there will be important environmental consequences.

The blue paper says policymakers will need to weigh the benefits and costs associated with making mariculture production financially feasible. No production system can have zero environmental impact, and it is important to assess the relative costs and benefits associated with food production options (including the decision of inaction).

Sustainable Ocean Economy blue papers

Australia is a member of the High Level Panel for a Sustainable Ocean Economy, established in 2018. The new ocean action agenda is launching this December. Blue Papers prepared for the panel have been published online.