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Fish—including finfish and shellfish—are an important item in the human food basket, contributing 17 percent of the global animal-based protein supply in 2010. They are an especially valuable food source in developing countries, where more than 75 percent of the world’s fish consumption occurs. In addition to protein, fish contain micronutrients and long-chain omega-3 fatty acids that are essential for maternal and child health, but often deficient in the diets of the poor.

However, the global supply of wild-caught fish has long peaked and is unlikely to rise again unless overexploited stocks are rehabilitated. As world fish consumption continues to grow, aquaculture (fish farming) has emerged to meet demand. Already, just under half of all fish that people consume come from aquaculture, which is one of the world’s fastest-growing animal food producing sectors. With the supply of wild-caught fish stagnant, any future increase in world fish consumption will need to be supplied by aquaculture.

In a resource-constrained world, aquaculture could be an attractive option for expanding animal protein supply. Farmed finfish are similar in feed conversion efficiency to poultry, and much more efficient than beef. Filter-feeding carp and mollusks are even more efficient producers of animal protein, as they require no human-managed feeds and can improve water quality. Because the aquaculture sector is relatively young compared with terrestrial livestock sectors, it offers great scope for technical innovation to further increase resource efficiency.

For global fish availability to meet projected demand, we estimate that aquaculture production will need to more than double by mid century, rising from 67 million tons (Mt) in 2012 to roughly 140 Mt in 2050. This level of growth could bring about significant food security and development benefits. For example, we estimate it could close roughly 14 percent of the “gap” between global animal protein consumption today and that needed in 2050. In addition, it could boost income and employment, particularly in developing countries where most aquaculture growth will occur.

However, as aquaculture assumes greater significance as a global food production system, concerns about its environmental and social impacts have arisen. As in other animal production sectors, several aquaculture inputs—land, freshwater, feed, and energy—are associated with significant environmental impacts. At the same time, the availability of these inputs is limited, and will likely become even more so in the future. Unless the aquaculture industry finds a way to produce more fish while minimizing its reliance on these limited inputs, its growth will be hampered. In addition, water pollution, fish diseases, and escapes continue to compromise the sustainability of the sector.

Therefore, for aquaculture to more than double production—and for that growth to be sustainable—the sector must improve its productivity while at the same time improving its environmental performance. To achieve “sustainable intensification,” aquaculture must:

• Advance socioeconomic development;

• Provide safe, nutritious food;

• Increase production of fish relative to the amount of land, water, feed, and energy used; and

• Minimize water pollution, fish diseases, and escapes.

How large could aquaculture’s resource demands and environmental impacts be in 2050? To answer this question, we used a new life cycle assessment conducted by WorldFish and Kasetsart University. We first assessed aquaculture’s environmental performance in 2010, and found that environmental impacts varied greatly depending on the species farmed (e.g., carp, mollusks, shrimp, tilapia, catfish, salmon):

• Freshwater ponds (e.g., for carp or tilapia) required the most land and freshwater per unit of farmed fish produced, while marine cages (e.g., for salmon) required only a very small amount of land and water (for production of crop-based feeds).

• Production of catfish and shrimp stood out for its high greenhouse gas intensity.

• Production of salmon, shrimp, and other marine fish used the largest amounts of wild fish-based feed per unit of farmed fish produced, while species that feed lower on the food chain (e.g., carp, tilapia, catfish) used smaller amounts.

• Of all species groups, only bivalve mollusks (e.g., oysters, clams, mussels, scallops) performed well across all environmental impact categories.

We also found that aquaculture’s environmental impacts in 2010 varied by level of production intensity. Intensification pulled impact indicators in two directions. To date, intensification has led to a decrease in the use of land and freshwater per unit of farmed fish produced. However, intensification has also led to an increase in the use of energy and fish-based feed ingredients, as well as an increase in water pollution, per unit of farmed fish produced. Disease risks also rise in intensive systems. These tradeoffs suggest that “sustainable intensification” is easier said than done—and that efforts to intensify aquaculture production should aim at mitigating the negative impacts of intensification.

We then projected environmental impacts under “business as usual” aquaculture production of 140 Mt in 2050, as well as seven alternative scenarios:

• Scenario 1: 10 percent improved efficiency in input use

• Scenario 2: Significant intensification (50 percent of extensive farms become semi-intensive, 50 percent of semi-intensive farms become intensive)

• Scenario 3: Shifting energy supply (higher use of renewable energy)

• Scenario 4: Adoption of current best practices (all farmers in 2050 achieve efficiency of the best farmers in 2010 in terms of feed conversion ratios)

• Scenario 5: Shifting species mix (higher share of freshwater species, lower share of marine species)

• Scenario 6: Replacement of fishmeal and fish oil with crop-based ingredients

• Scenario 7: Combined effect of Scenarios 1, 3, 4, and 6

We found that holding aquaculture’s environmental impacts to 2010 levels—let alone reducing them—will be a real challenge, given the sector’s projected rapid growth to 2050. Under most scenarios, most impacts roughly double between 2010 and 2050, although impacts range from slightly below 2010 levels (e.g., greenhouse gas emissions decline with higher use of renewable energy) to nearly tripling (e.g., greenhouse gas emissions rise under significant intensification). Scenarios 1, 3, and 4 reduce nearly all environmental impacts relative to “business as usual” growth. Scenarios 2, 5, and 6 offer mixed results and tradeoffs across the impact categories. Scenario 7 exhibits the lowest impacts, indicating that for maximum effect, a variety of solutions should be implemented at the same time.

How can the world lift constraints to aquaculture’s growth while minimizing associated environmental impacts? We analyzed eight case studies from around the world to answer this question, and found four categories of factors that have improved aquaculture’s productivity and environmental performance:

• Technological innovation and adoption (in breeding, feeds, production systems, disease control, and environmental management)

• Market forces (related to resource scarcity and price signals)

• Public policy (regulation and standards; spatial planning and zoning; fiscal incentives; publicly funded research, extension, and training)

• Private initiatives (certification programs, purchasing standards, codes of conduct, research, advocacy, service delivery)

Resource scarcity will intensify between now and 2050, and rising input prices will continue to provide some incentive for producers to improve productivity and environmental performance. But our analysis shows that the scale of projected aquaculture production growth will likely offset efficiency gains achieved from market forces alone. How can the world accelerate further gains in productivity and environmental performance?

We offer five recommendations aimed at catalyzing transformational change in the aquaculture sector:

1) Increase investment in technological innovation and transfer. Technological advances will be needed in four interrelated areas:

• Breeding and genetics. Establish or expand selective breeding efforts—aimed at countries and species with the highest levels of production (e.g., Chinese carps) and at areas of low productivity and high need for aquaculture growth (e.g., in sub-Saharan Africa)—to promote efficient resource use, reduce problems of disease and escapes, and lower production costs.

• Disease control. Combine new technologies (e.g., diagnostic technologies, vaccines) and wider application of best management practices to combat disease problems.

• Nutrition, feeds, and feeding management. Minimize farmers’ costs and aquaculture waste by increasing feeding efficiencies, and continue to develop alternatives to fish oil in aquaculture feeds.

• Low-impact production systems. Recirculating aquaculture systems, biofloc technology, and integrated systems perform well across most indicators of productivity and environmental performance. Conduct additional research to understand and manage resource tradeoffs, bring down production costs, and develop additional low-impact systems that ease resource constraints.

2) Use spatial planning and zoning to guide aquaculture growth at the landscape and seascape level. If conducted in a participatory way, these approaches can lessen the inevitable conflicts between a growing aquaculture industry and other economic actors, reduce cumulative impacts caused by many farmers operating in the same area, and help minimize risks associated with climate change.

3) Shift incentives to reward improvements in productivity and environmental performance. Government initiatives (e.g., regulations, standards, taxation and subsidy policies, market-based mechanisms) and private initiatives (e.g., certification, purchasing standards) can complement landscape-level planning (Recommendation 2) to realign incentives to encourage and reward sustainable production systems. These incentives should help the aquaculture industry reduce the environmental impacts of its most widely used production systems, and stimulate investment in and deployment of low-impact production systems.

4) Leverage the latest information technology to drive gains in productivity and environmental performance. Advances in satellite technology, digital mapping technology, ecological modeling, open data, and connectivity mean that global-level monitoring and planning systems that encourage and support sustainable forms of aquaculture development may now be possible. A platform integrating these technologies could help governments improve spatial planning and monitoring, help the industry plan for and demonstrate sustainability of operations, and help civil society report success stories and hold industry and government accountable.

5) Shift fish consumption toward low-trophic farmed species. Increasing demand for low-trophic farmed fish species (e.g., tilapia, catfish, carp, bivalve mollusks) relative to “business as usual” growth in fish consumption would lead to more efficient use of scarce wild fish resources and could ease fishing pressure on marine and freshwater ecosystems. In industrialized countries, substituting low-trophic farmed species into processed fish products; changing public food procurement policies to favor low-trophic farmed species; and selling the benefits of these species—such as affordability and taste—can all help to alter consumption patterns. In emerging economies, where most aquaculture production and fish consumption is currently of low-trophic species, this strategy could reduce the growth in consumption of high-trophic species that is expected to occur as billions of people enter the global middle class in coming decades.

The global aquaculture industry is dynamic and diverse. National governments, the aquaculture industry, development agencies, international organizations, nongovernmental organizations (NGOs), private foundations, and farmers all have a role to play in implementing these recommendations. One thing is clear: improving the productivity and environmental performance of aquaculture—and ensuring it provides safe, affordable, and nutritious food to millions of people around the world—is an important item on the menu for a sustainable food future.