Data-mining social media platforms highlights conservation action for the Mediterranean Critically Endangered blue shark Prionace glauca

The Mediterranean Sea represents an area of elevated risk of extinction for sharks, where data deficiency is a pervasive problem. To compensate for such a paucity of information, this study investigated the use of social media content as a complementary approach to evaluate the distribution and habitat use of the Critically Endangered blue shark Prionace glauca in coastal waters, as well as public perceptions of the sharks. Through social media data mining a total of 146 records, comprising 158 individual blue sharks approaching Italian coastal waters, have been recorded from 2011 to 2020. This study revealed that, over the past decade, blue sharks regularly visited Italian coastal habitats for extended periods of time. Differences in the temporal distribution of blue sharks by sex and size appear to be linked to reproductive activity. The higher number of adult females approaching the shore in spring and the increase in young-of-the-year (YOY) sightings in the following months possibly indicate parturition in coastal waters. Spatial analyses also showed that certain Italian coastal areas, such as those in Calabria and Puglia, were preferred coastal habitats for this species. Results also indicate that social media platforms can be considered an ever-growing source of data on wildlife, which can shed light on the occurrence and distribution of endangered shark species in poorly known habitats. Furthermore, social media platforms should be used for awareness campaigns to educate the public, as this study showed that negative reactions to shark encounters remain widespread.