Threatened fish species in the Northeast Atlantic are functionally rare

Aim The criteria used to define the International Union for Conservation of Nature (IUCN) Red List categories are essentially based on demographic parameters at species level, but they do not integrate species' traits or their roles in ecosystems. Consequently, current IUCN-based protection measures may be sufficient conserve ecosystem functioning and services. Some have a singular combination associated with unique functions. Such functionally distinct increasingly recognized as key facet biodiversity since are, by definition, irreplaceable. aim this study is investigate whether threatened also rare identify which determine extinction risk. Location European continental shelf seas. Time period 1984–2020. Major taxa studied Marine fish. Methods Using newly compiled trait information 425 marine fish waters, more than 30 years scientific bottom trawl surveys, we estimated functional distinctiveness, restrictedness scarcity each cross-referenced it IUCN conservation status. Results In seas, 38% (9 out 24 species) were identified most distinct. By mapping risk multidimensional space, showed that greatest long-lived high trophic level. We sparsely distributed (4% total area average) scarce abundances (<1% relative mean abundance common species). Main Conclusions Because substantial proportion thus play functioning, stress traits—especially rarity—should become an indispensable step development management plans.