Global food systems use three-quarters of the planet’s freshwater, occupy half of ice-free land and emit a quarter of all greenhouse gas emissions. In order to feed the future without overwhelming planetary boundaries, this environmental footprint must be reduced. Blue food, long overlooked in global policy dialogues, offers an opportunity to contribute to more sustainable diets. This paper provides the most comprehensive estimate of blue food’s environmental performance to date, and for the first time, compares stressors across the diversity of farmed and wild aquatic species.
Leveraging data from more than 2,500 fisheries and aquaculture farms, this paper presents standardized estimates for greenhouse gas, nitrogen and phosphorus emissions, and freshwater and land use for the majority of current blue food production. The study reveals which species are already performing well and identifies opportunities for further reducing environmental footprints. Results provide policymakers with targeted recommendations on how to realize the potential contributions of blue food to sustainable and nutritious diets while avoiding undesirable trade-offs.
Across assessed blue foods, farmed seaweeds and bivalves like mussels generate the lowest greenhouse gas emissions, followed by small pelagic capture fisheries like sardines.
Flatfish and lobster fisheries and an assortment of farmed diadromous fish generate the highest greenhouse gas emissions, an assortment of farmed marine species emit the most nitrogen and phosphorus, farmed silver and bighead carp use the most water and milkfish use the most land.
Farmed salmon, trout, fed carps, catfish and tilapia performed similarly or better than chicken—often considered the most efficient terrestrial animal—across the considered environmental stressors.
For aquaculture, increasing the efficiency of aquaculture feed to blue food weight gain represents the biggest opportunity for improving environmental performance.
For capture fisheries, reducing fuel use by optimizing fishing gear and improving fisheries management represent the biggest opportunities for improving environmental performance.
Taxes, subsidies and dietary guidelines that consider environmental performance can help shift demand towards low-stressor blue foods, while public funding to support research and development can improve on-farm practices to reduce the environmental pressures stemming from aquaculture.