Data mining on YouTube reveals fisher group-specific harvesting patterns and social engagement in recreational anglers and spearfishers

Data about recreational fisheries are scarce in many areas of the world. In the absence of monitoring data collected in situ, alternative data sources, such as digital applications and social media platforms, have the potential to produce valuable insights. Yet, the potential of social media for drawing insights about recreational fisheries is still underexplored. In this study, we applied data mining on YouTube videos to better understand recreational fisheries targeting common dentex (Dentex dentex), an iconic species of Mediterranean recreational fisheries. We chose this model species because of ongoing controversies about the relative impact of recreational angling and recreational spearfishing on its conservation status. In Italy alone, from 2010 to 2016 recreational spearfishers posted 1051 videos compared to 692 videos posted by recreational anglers. Only the upload pattern of spearfishing videos followed a seasonal pattern with peaks in July, suggesting seasonality of spearfishing catches of D. dentex – a trend not found for anglers. The average mass of the fish declared in recreational angling videos (6.43 kg) was significantly larger than the one in spearfishing videos (4.50 kg). Videos posted by recreational spearfishers received significantly more likes and comments than those posted by recreational anglers, suggesting that the social engagement among recreational spearfishers was stronger than in anglers. We also found that the mass of the fish positively predicted social engagement in recreational spearfishing videos, but not in videos posted by recreational anglers. This could be caused by the generally smaller odds of catching large D. dentex by spearfishing, possibly explaining why posting videos with particularly large specimen triggered larger social engagement by recreational spearfishers. Our case study demonstrates that data mining on YouTube can be a powerful tool to provide complementary data on controversial and data-poor aspects of recreational fisheries.