Based on the question of how much food we can sustainably obtain from the sea by 2050, an analysis of the main food-producing sectors in the sea is presented: wild fisheries, finfish mariculture and bivalve mariculture. From this, encouraging curves emerge for sustainable supply, taking into account ecological, economic, regulatory, and technological limits.
Human population growth, rising incomes and preference shifts will considerably increase global demand for nutritious food in the coming decades. Malnutrition and hunger still plague many countries, and projections of population and income by 2050 suggest a future need for more than 500 megatons (Mt) of meat per year for human consumption.
“Scaling up the production of land-derived food crops is challenging, because of declining yield rates and competition for scarce land and water resources.”
Land-derived seafood (freshwater aquaculture and inland capture fisheries; seafood is used to denote any aquatic food resource, and food from the sea for marine resources specifically) has an important role in food security and global supply, but its expansion is also constrained.
Similar to other land-based production, the expansion of land-based aquaculture has resulted in substantial environmental externalities that affect water, soil, biodiversity and climate, and which compromise the ability of the environment to produce food.
Despite the importance of terrestrial aquaculture in seafood production, many countries—notably China, the largest inland-aquaculture producer—have restricted the use of land and public waters for this purpose, which constrains expansion.
“Although inland capture fisheries are important for food security, their contribution to total global seafood production is limited, and expansion is hampered by ecosystem constraints.”
Thus, to meet future needs (and recognizing that land-based sources of fish and other foods are also part of the solution), the question is whether sustainable production of food from the sea plays an important role in future supply.
Here we present an extensive analysis of the main food-producing sectors in the ocean—wild fisheries, finfish mariculture and bivalve mariculture—with an estimation of ‘sustainable supply curves’ that account for ecological, economic, regulatory, and technological constraints.
Sustainably increasing food from the sea
Four main pathways by which food supply from the ocean could increase are:
(1) improving the management of wild fisheries;
(2) implementing policy reforms of mariculture;
(3) advancing feed technologies for fed mariculture; and
(4) shifting demand, which affects the quantity supplied from all three production sectors.
Although mariculture production has grown steadily over the past 60 years (Figure 1) and provides an important contribution to food security, the vast majority (over 80%) of edible meat from the sea comes from wild fisheries (Figure 1b).
Over the past 30 years, supply from this wild food source has stabilized globally despite growing demand worldwide, which has raised concerns about our ability to sustainably increase production.
Of nearly 400 fish stocks around the world that have been monitored since the 1970s by the UN Food and Agriculture Organization (FAO), approximately one third is currently not fished within sustainable limits. Indeed, overfishing occurs often in poorly managed (‘open access’) fisheries.
This is disproportionately true in regions with food and nutrition security concerns. In open-access fisheries, fishing pressure increases as the price rises: this can result in a ‘backward-bending’ supply curve (the OA curve in Figure 2a), in which higher prices result in the depletion of fish stocks and reduced productivity—and thus reduced equilibrium food provision.
Fishery management allows overexploited stocks to rebuild, which can increase long-term food production from wild fisheries. Two hypothetical pathways by which wild fisheries could adopt improved management are presented (Figure 2a).
First, independent of economic conditions, governments can impose reforms in fishery management. The resulting production in 2050 from this pathway—assuming that fisheries are managed for maximum sustainable yield (MSY)—is represented by the MSY curve in Figure 2a, and is independent of price.
The second pathway explicitly recognizes that wild fisheries are expensive to monitor (for example, via stock assessments) and manage (for example, via quotas)—management reforms are adopted only by fisheries for which future profits outweigh the associated costs of improved management.
“When management entities respond to economic incentives, the number of fisheries for which the benefits of improved management outweigh the costs increases as demand (and thus price) increases.”
This economically rational management endogenously determines which fisheries are well-managed, and thus how much food production they deliver, resulting in supply curve designated R in Figure 2a.
Although the production of wild fisheries is approaching its ecological limits, current mariculture production is far below its ecological limits and could be increased through policy reforms, technological advancements and increased demand.
The explanations for why food production from mariculture is currently limited, and describe how the relaxation of these constraints gives rise to distinct pathways for expansion are presented in Figure 2b. The first pathway recognizes that ineffective policies have limited the supply.
Lax regulations in some regions have resulted in poor environmental stewardship, disease and even collapse, which have compromised the viability of food production in the long run (curve M1 in Figure 2b). In other regions, regulations are overly restrictive, convoluted and poorly defined, and therefore limit production (curve M2 in Figure 2b).
In both cases, improved policies and implementation can increase food production by preventing and ending environmentally damaging mariculture practices (the shift from M1 to M3 in Fig. 2b) and allowing for environmentally sustainable expansion (the shift from M2 to M3 in Fig. 2b).
The second pathway to sustainably increase mariculture production is through further technological advances in finfish feeds.
“Currently, most mariculture production (75%) requires some feed input (such as fishmeal and fish oil) that is largely derived from wild forage fisheries.”
If fed mariculture continues using fishmeal and fish oil at the current rate, its growth will be constrained by the ecological limits of these wild fisheries. A reduced reliance on fishmeal and fish oil is expected to shift the supply curve of fed mariculture to the right (curve M4 in Figure 2b).
The final pathway is a shift in demand (aggregated across all global fish consumers), which affects all three production sectors. When the sustainable supply curve is upwardsloping, an increase in demand increases food production, for example, from rising population, income or preferences.
Estimated sustainable supply curves
The supply curves of food from the sea in 2050 for the three largest food sectors in the ocean are estimated as: wild fisheries, finfish mariculture and bivalve mariculture. Global supply curves for marine wild fisheries are constructed using projected future production for 4,702 fisheries under alternative management scenarios (Figure 3a).
Managing all fisheries to maximize food production (MSY) would result in 57.4 Mt of food in 2050, representing a 16% increase compared to the current food production (Figure 3a). Under a scenario of economically rational reform, the price influences production (Figure 3a).
“At current mean global prices, this scenario would result in 51.3 Mt of food (77.4 Mt live-weight equivalents)—a 4% increase compared to current food production.”
The policy reform scenario—which assumes mariculture policies are neither too restrictive nor lax (curve M3 in Figure 2b), but that fishmeal and fish oil requirements match present-day conditions—produces a modest additional 1.4 Mt of food at current prices.
In this scenario, marine-based feed inputs limit mariculture expansion even as the price increases considerably. At current prices, economically rational production could lead to an increase from 2.9 Mt to 80.5 Mt of food (Figure 3c).
“Even if the model underestimates costs by 50%, policy reforms would increase the production potential of both fed and unfed mariculture at current prices.”
For fed mariculture, this remains true even when evaluating mariculture species with different feed demands (Atlantic salmon, milkfish and barramundi).
Estimates of future food from the sea
The supply curves suggest that all three sectors of ocean food production are capable of sustainably producing much more food than they do at present. The quantity of seafood demanded will also respond to price (Figure 4).
The intersections of future demand and sustainable supply curves provide an estimate of future food production from the sea. Because it is a substantial contributor to fish supply and—in some instances—acts as a market substitute for seafood.
Even under current demand curves (green curves in Figure 4), the economically rational reform of marine wild fisheries and sustainable mariculture policies under the technological innovation (ambitious) scenario could result in a combined total of 62 Mt of food from the sea per year, 5% more than the current levels (59 Mt).
“Under the ‘future demand’ scenario (purple curves in Figure 4), total food from the sea is projected to increase to 80 Mt. If demand shifts even more, the intersection of supply and demand is expected to increase to 103 Mt of food.”
Using the approach used by the FAO to estimate future needs, the world will require an additional 177 Mt of meat by 2050—the results suggest that additional food from the sea alone could plausibly contribute 12–25% of this need.
The results also suggest that the future composition of food from the sea will differ substantially from the present (Figure 5).
Although wild fisheries dominate edible marine production at present, the projection is that by 2050 up to 44% of edible marine production could come from mariculture, although all sectors could increase production.
Although even more substantial increases are technically possible (for example, fed mariculture alone is capable of generating at least the benchmark 177 Mt of additional meat), actually realizing these gains would require enormous shifts in demand.
Global food demand is rising, and expanding land-based production is fraught with environmental and health concerns. Because seafood is nutritionally diverse and avoids or lessens many of the environmental burdens of terrestrial food production, it is uniquely positioned to contribute to both food provision and future global food and nutrition security.
The estimated sustainable supply curves of food from the sea suggest substantial possibilities for future expansion in both wild fisheries and mariculture.
“The potential for increased global production from wild fisheries hinges on maintaining fish populations near their most-productive levels.”
For underutilized stocks, this will require expanding existing markets. For overfished stocks, this will require adopting or improving management practices that prevent overfishing and allow depleted stocks to rebuild. Climate change will further challenge food security.
Estimates suggest that active adaptation to climate-induced changes will be crucial in both wild fisheries and mariculture. Climate-adaptive management of wild fisheries and decisions regarding mariculture production could improve food provision from the sea under conditions of climate change.
The sea can be a much larger contributor to sustainable food production than is currently the case, and that this comes about by implementing a range of plausible and actionable mechanisms.
“The price mechanism—when it motivates improved fishery management and the sustainable expansion of mariculture into new areas—arises from change in demand, and acts on its own without any explicit intervention.”
The feed technology mechanism is driven by incentives to innovate, and thus acquire intellectual property rights to new technologies. When intellectual property is not ensured or to achieve other social goals, there may be a role for public subsidies or other investments in these technologies.
The policy mechanism pervades all three production sectors, and could make—or break—the ability of food from the sea to sustainably, equitably and efficiently expand in the future.
This is a summarized version developed by the editorial team of Aquaculture Magazine based on the review article titled “THE FUTURE OF FOOD FROM THE SEA” developed by CHRISTOPHER COSTELLO – University of California; LING CAO – Shanghai Jiao Tong University, STEFAN GELCICH Pontificia Universidad Católica de Chile; MIGUEL Á. CISNEROS-MATA – Instituto Nacional de Pesca y Acuacultura, Guaymas, Mexico; CHRISTOPHER M. FREE – University of California. The original article was published in Nature in AUGUST 2020.
The full version, including tables and figures, can be accessed online through this link: https://doi.org/10.1038/s41586-020-2616-y