The sustainability of aquaculture has been debated intensely since 2000, when a review on the net contribution of aquaculture to world fish supplies was published in Nature. This paper reviews the developments in global aquaculture from 1997 to 2017, incorporating all industry sub-sectors and highlighting the integration of aquaculture in the global food system.
Inland aquaculture—especially in Asia—has contributed the most to global production volumes and food security. Major gains have also occurred in aquaculture feed efficiency and fish nutrition, lowering the fish-in–fish-out ratio for all fed species, although the dependence on marine ingredients persists and reliance on terrestrial ingredients has increased. The culture of both molluscs and seaweed is increasingly recognized for its ecosystem services; however, the quantification, valuation, and market development of these services remain rare. The potential for molluscs and seaweed to support global nutritional security is underexploited. Management of pathogens, parasites, and pests remains a sustainability challenge industry-wide, and the effects of climate change on aquaculture remain uncertain and difficult to validate. Pressure on the aquaculture industry to embrace comprehensive sustainability measures during this 20-year period have improved the governance, technology, siting, and management in many cases.
Twenty years ago, Nature published a review characterizing aquaculture as a possible solution, and a contributing factor, to the decline in fisheries stocks worldwide. At the time, the commercial aquaculture sector was flourishing, whereas the production of capture fisheries remained stagnant. The farmed (live-weight) production of fish and shellfish had almost tripled from 10 million tonnes (Mt) in 1987 to 29 Mt in 1997, and roughly 300 species of animals, plants, and algae were being cultivated worldwide. The paper placed greater emphasis on fed marine species than on freshwater and molluscan species and cautioned that the net positive contribution of aquaculture to world fish supplies could not be sustained unless the sector reduced its use of wild fish in feed as well as its environmental impacts.
This Review covers global trends in aquaculture over the past 20 years, citing a selection of the most relevant papers (additional reviewed articles are listed in the Supplementary Information). In 2017, aquaculture supplied more than 80 Mt of fish and shellfish and 32 Mt of seaweeds, encompassing around 425 farmed species. Three main patterns of aquaculture development have characterized the sector as it matured: continued growth in the volume and value chains of freshwater aquaculture; advances in fish nutrition, genetics, and alternative types of feed that reduce the use of wild fish in aquafeed formulations; and expanded culture of extractive bivalves and seaweeds with the potential to provide a wide range of food, industrial, and ecosystem services.
These trends reveal increasingly tight connections between land and sea. Continuing a long history of inland production, the share of freshwater fish raised on compound feed, which is made largely from terrestrial and some marine ingredients, has increased over the past two decades. Meanwhile, the inclusion of plant-based ingredients in aquafeed has increased, and the production of extractive species (molluscs and seaweed) that filter nutrients from terrestrial and marine food systems has grown. Aquaculture has thus become more integrated into the global food system, with rapid growth in production and major transformations in feed ingredients, production technologies, farm management, and value chains. Through aquaculture growth, consumers from low- to high-income nations have benefited from year-round availability and access to aquatic foods, which are rich in protein and micronutrients. The sector produces far more than fish, shellfish, and algae for direct human consumption. It also generates products used in food processing, feed, fuels, cosmetics, nutraceuticals, pharmaceuticals, and a variety of other industrial products, and it contributes to a range of ecosystem services.
Despite impressive gains, the aquaculture sector still faces serious challenges that, in some cases, undermine its ability to achieve sustainable outcomes. The sector has generally embraced a business and societal expectation of environmentally and socially sound practices. Globally traded finfish and crustacean systems are progressively improving their environmental performances, either independently or in response to government regulation, private and public sector standards, and market incentives. Many aquaculture systems, however, still lack the motivation to meet sustainability criteria because their targeted markets do not reward producers through improved prices or access. At the same time, molluscs, filter-feeding finfish, and seaweeds have sustainable characteristics, particularly because they do not rely on aquafeed, but instead remove nutrients from the water column. In summary, as the global industry continues to expand, its contribution to economic social and environmental performance varies across a wide diversity of aquaculture systems.
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