Authors: Sbragaglia, Valerio; Espasandín Soneira, Lucía;Coll, Marta;

Mining data about recreational fisheries on social media can increase our understanding of potential threats of such fishing activity on biodiversity. At the same time, such data can contribute to understand biodiversity trends and, most importantly, the ecological and social dimension of biodiversity changes in response to climate change. I will present three case studies where YouTube data mining about recreational fishing in the North-Western Mediterranean Sea demonstrated to be useful to: (i) document unexpected harvesting patterns of an iconic fish species that can provide crucial information for the conservation of the species; (ii) characterize macroecological patters of groupers such as ontogenetic deepening and distributional range shifts, which can unveil climate change effects on these emblematic top predators of coral and rocky reefs; (iii) quantify polarized sentiments of recreational fishers towards an invasive species that is extending its distribution in response to climate change, thereby providing information for possible management interventions. In summary, digital tools in the context of recreational fishing can have a double and overlooked advantage in monitoring marine biodiversity trends and threats from an ecological and social perspective.