Using social media to identify recreational bluefish angling in the Mediterranean and Black Sea

Filling the information gap on recreational fisheries is an important challenge due to difficulties in monitoring and collecting data. The use of citizen science based on social media has recently emerged as a digital data source. This study aims to explore the extent of recreational bluefish angling in the Turkish coasts of the Mediterranean and adjacent seas (Aegean Sea, Marmara Sea and Black Sea) by using existing knowledge that is publicly available on YouTube and to highlight conservation priorities. For this purpose, a total of 14,214 bluefish individuals were identified from 929 YouTube videos posted between 2017 and 2019. The highest number of videos were uploaded from the Aegean Sea and the Marmara Sea with 47% and 40% respectively. Our results show that juvenile bluefish were predominantly caught in the Marmara Sea during the bluefish migration that occurs from the Black Sea to the Aegean Sea in autumn and from the Aegean Sea to the Black Sea in spring via the Marmara Sea. In addition, recreational bluefish anglers predominantly caught adult bluefish throughout the year in the Aegean Sea. This is likely related to the aggregations of bluefish around sea-cages along the Aegean Sea coast of Turkey. These results highlight conservation and management priorities for recreational bluefish angling for policymakers, and therefore prove the suitability of digital data extracted from social media. •YouTube can complement and improve our understanding of recreational fishing.•In the Marmara Sea, juvenile bluefish are vulnerable to recreational angling during their migration in spring and autumn.•In the Aegean Sea, adult bluefish are likely vulnerable to recreational angling due to their aggregations around sea-cages.