Digital footprints: documenting marine mammal distribution through social media reports

Abstract Conducting comprehensive assessments of marine mammal biodiversity presents logistical challenges due to the time-intensive, costly, and resource-demanding data collection of traditional surveys. Recent advancements in social media data mining offer a promising supplementary data source. This study verified marine mammal sighting records across the state of Victoria (Australia) extracted from six Facebook groups. Sighting reports posted from January 2020 through to October 2024 were manually logged and assessed for data completeness, quality, and their potential for expert verification. A total of 3,209 sighting reports were documented, of which 1,124 were verified to species level, with ten species verified after expert review. This included species that are currently listed as critically endangered, endangered, vulnerable, and data deficient by the International Union for Conservation and Nature (IUCN). Verified records were then compared to the Global Biodiversity Information Facility (GBIF) database to evaluate their unique spatial contributions. For Tursiops spp., orca, humpback whales, blue whales, and southern right whales, Facebook contributed a higher proportion of geographically unique datapoints when compared to the GBIF dataset. In contrast, GBIF generally yielded larger estimated range extents, except for the southern right whale, for which Facebook provided a broader range. These findings highlight the value of extracting and verifying data from social media platforms to incorporate into marine biodiversity assessments. When appropriately curated, platforms such as Facebook can provide low-cost, time-efficient, and high-volume supplementary data that can strengthen the monitoring of large coastal regions.