Salmon has one of the most efficient feed-to-food conversion rates among farmed animals, but its high trophic level makes salmon aquaculture a major consumer of marine resources — including species that are consumed directly by people, such as herring and mackerel. Re-allocating species currently used in salmon feeds towards direct human consumption can increase the overall amount of nutritious seafood while avoiding increases in wild-caught fish supply. Most edible feed fish contains higher concentrations of omega-3 fatty acids, iodine, calcium, iron and vitamin A than farmed salmon. Nutrient retention approaches can drive better performance of aquaculture and identify pathways towards sustainable growth.

See Willer et al.

Food that is lost or wasted along supply chains contributes to climate change, depletes natural resources, threatens economic stability and compromises progress towards food security. A global database identifies regional hotspots in low- and middle-income regions where food loss and waste (FLW) in agricultural production and post-harvest handling and storage contribute towards nutrient losses and environmental footprints. Between 2004 and 2014, FLW increased by a quarter, especially in regions confronted with food insecurity. Overconsumption in high-income regions drives FLW elsewhere via international trade. Policies and strategies aimed at reducing FLW must consider the complex interplay between food production, trade, consumption patterns, and their social and environmental impacts.

See Gatto et al.

Urban food systems still rely almost entirely on imported goods and services. The acceleration of urbanization is therefore expected to place greater demands on resources that are already strained by shifting land use, rising inequalities and climate change. Urban agriculture represents a promising lever to reduce this pressure while inducing a broader transformative change towards urban resilience and sustainability. Scaling up urban agriculture will need to address diversity, heterogeneity, connectivity, spatial synergies and trade-offs, nonlinearity, scale and polycentricity. This transition could prompt the decentralization of urban food supplies, bolster ecosystem services, mitigate transboundary environmental footprints and advance urban resilience. Multi-phase developmental pathways, including dynamics, accelerators and feedback associated with scaling up urban agriculture, should be considered in support of food security for the growing urban population.

See Qiu et al.