Human targeting of morphologically unique fishes amplifies the risk of functional erosion

Human societies are drawing on wild species for food, fuel, medicines, and recreation. Yet, it remains unclear whether different types of human use target species with common or unique ecological roles. Here we show that humans use a fourth (26%) of the freshwater fish species and these species occupy almost half (45.2%) of the global spectrum of fish morphological diversity. Yet, used species harbour unique trait combinations, that differ according to the way humans use the species such as fisheries, aquaculture, game fish and aquarium. Moreover, the species targeted by humans are characterised by traits that are predominantly associated with threatened species. By simulating the extinction of threatened species used by humans, we revealed a pronounced and non-random erosion of the morphological spectrum. Understanding the trait-based impacts of human use is thus essential to buffer human impact on natural resources. Conservation should therefore safeguard threatened species but also preserve irreplaceable trait combinations that support unique ecological strategies. A quarter of the world’s freshwater fish species are used for food, recreation, or ornamental purposes. These species harbour unique morphologies, many threatened, whose loss would erode irreplaceable ecological strategies.