The recovery of stray biodiversity data in environmental assessment reports

The global biodiversity crisis, driven by habitat loss, climate change, and overexploitation, demands efficient data management and accessibility to inform conservation decisions. While open-access biodiversity data have increased, a substantial portion, termed “dark data,” remains unpublished and inaccessible. We explored the mobilization of dark data existing in Environmental Assessment (EA) reports in Spain to improve the Digital Accessible Knowledge for 43 field-recorded threatened species. Based on the IUCN Red List criteria, we evaluated the impact of EA-related dark data on two required metrics: the extent of occurrence (EOO) and area of occupancy (AOO). Our results show that integrating dark data increased EOO and AOO for 23% and 93% of the field-recorded threatened species, respectively, including endangered species like Aquila adalberti. We highlight the importance of mobilizing data collected during the EA processes and ensuring that data are made findable, accessible, interoperable, and reusable (FAIR) to inform conservation decisions. Mobilizing EA-related dark data offers a cost-effective approach by which to strengthen biodiversity management, facilitate decision-making, and justify biodiversity conservation.