Environmental performance of blue foods

Abstract

Fish and other aquatic foods (blue foods) present an opportunity for more sustainable diets 1,2 . Yet comprehensive comparison has been limited due to sparse inclusion of blue foods in environmental impact studies 3,4 relative to the vast diversity of production 5 . Here we provide standardized estimates of greenhouse gas, nitrogen, phosphorus, freshwater and land stressors for species groups covering nearly three quarters of global production. We find that across all blue foods, farmed bivalves and seaweeds generate the lowest stressors. Capture fisheries predominantly generate greenhouse gas emissions, with small pelagic fishes generating lower emissions than all fed aquaculture, but flatfish and crustaceans generating the highest. Among farmed finfish and crustaceans, silver and bighead carps have the lowest greenhouse gas, nitrogen and phosphorus emissions, but highest water use, while farmed salmon and trout use the least land and water. Finally, we model intervention scenarios and find improving feed conversion ratios reduces stressors across all fed groups, increasing fish yield reduces land and water use by up to half, and optimizing gears reduces capture fishery emissions by more than half for some groups. Collectively, our analysis identifies high-performing blue foods, highlights opportunities to improve environmental performance, advances data-poor environmental assessments, and informs sustainable diets.The food system is a major driver of environmental change, emitting a quarter of all greenhouse gas (GHG) emissions, occupying half of all ice-free land, and responsible for three quarters of global consumptive water use and eutrophication 3,6 . Yet, it still fails to meet global nutrition needs 7 , with 820 million people lacking sufficient food 8 and with one in three people globally overweight or obese 9 . As a critical source of nutrition 8,10 generating relatively low average environmental pressures 1,2,11,12 , blue foods present an opportunity to improve nutrition with lower environmental burdens, in line with the Sustainable Development Goals to improve nutrition (Goal 2), ensure sustainable consumption and production (Goal 12), and sustainably use marine resources (Goal 14).Blue foods, however, are underrepresented in food system environmental assessments 13 and the stressors considered are limited 4 such that we have some understanding of GHG emissions 14,15 , but less of others such as land or freshwater use 16 . Where blue foods are included, they are typically represented by only one or a few broad categories (see, for example, refs. 3,17,18), masking the vast diversity within blue food production. Finally, estimates combining results of published life cycle assessments undertaken for different purposes, and consequently using incompatible methodologies 19,20 , cannot be compared reliably. It is therefore critical to examine the environmental performance across the diversity of blue foods in a robust, methodologically consistent manner to serve as a benchmark within the rapidly evolving se...

Aquatic foods to nourish nations

“…It is critical to consider where and how aquatic foods are produced, because environmental, social and economic impacts can vary widely across both the wild-capture and aquaculture sectors (Supplementary Methods). Despite the variability in environmental impacts across animal-source food-production sectors, aquaculture and wild-capture fisheries nearly always produce fewer greenhouse gas emissions and use less land than the farming of red meats, and many AASFs outperform poultry 33 . Sustainably and equitably achieving the human health benefits of expanded aquatic food production will require policies and technologies that mitigate impacts on adjacent ecosystems, industries and communities 21 .…”

Blue food demand across geographic and temporal scales

“…Chilean consumers have not yet demonstrated a strong preference for farmed salmon despite large-scale domestic production 70 . National health and environmental consequences of shifting diets from fish to terrestrial meats 60 , in addition to the environmental implications of expanding intensive salmon aquaculture to meet rising international demand 71 , illustrate the influence of global markets on nutrition and sustainability outcomes in countries like Chile that are significantly engaged in blue food trade.…”

“…Aquaculture has become progressively more sustainable over the past 20 years, yet environmental challenges persist 18 . As aquaculture intensifies in both freshwater and marine systems, feed formulations will depend increasingly on terrestrial crop production and will continue to rely on marine resources 18,71 . Bivalves are widely advocated as a sustainable seafood option, but it is unclear how dietary preferences will evolve for this group of species.…”

The contribution of fisheries and aquaculture to the global protein supply

“…An assessment of aquatic foods with low negative impacts (called blue foods) by Gephart et al ( 2021 ) identified farmed, bivalve molluscs and seaweed as the most environmentally benign sources. They also found silver and bighead carps to have the lowest GHG potential, but production of these finfish required considerable land and water.…”

“…The changing climatic conditions are expected to worsen in years to come, and this challenge provides opportunity to create new systems of food production and to abandon or lessen the use of some systems in efforts to conserve land, water, and energy as well as to reduce greenhouse gas emissions (GHGs) or increase carbon sequestration (Campbell et al, 2016 ; Gephart et al, 2021 ; Rosenzweig et al, 2021 ; Thiault et al, 2019 ). This is important because food production uses 38% of land (FAO, 2016 ) and 70% of freshwater (FAO, 2016 ), while resulting in 25–35% of global greenhouse gas emission (IPCC, 2013 ; Tubiello et al, 2014 ).…”