Global systematic review of the factors influencing shark bites

Abstract

Shark bites can cause substantial socio-economic and ecological challenges, including debates about bite-mitigation policies, economic impacts for tourism-dependent communities, and increased fear among beachgoers. The growing frequency of shark bites globally has not only raised public concern but also intensified the need for comprehensive research into their causes. Using the 2020 PRISMA standards, we conducted a systematic review to synthetize current knowledge on factors influencing shark bites. We found that research on shark-bite determinants began in 1948 and has gained increased attention since the mid-2000s. Our search protocol identified 61 peer-reviewed articles proposing 40 factors likely influencing shark bites. These factors included 22 short-term factors, e.g. likely explaining short spates of shark bites, 13 long-term factors, e.g. addressing changes in the number of shark bites over decades, and 5 factors influencing both short- and long-term scales. Key suggested factors were changes in human and shark population dynamics, environmental conditions, prey availability, shark-bite mitigation measures, and coastal urbanization. However, most factors were speculative, with only five studies since 1948 statistically testing the correlation between shark bites and merely eight factors. Furthermore, there was a lack of consensus among studies on the effects of most factors. Our review therefore highlights the wide range of factors potentially influencing shark-bite occurrences worldwide while revealing a paucity of rigorous scientific evidence. It emphasizes the critical need for further studies to formally test shark bite determinants, providing decision-makers actionable insights to develop effective strategies that reduce shark-bite risks while enhancing both human safety and shark conservation.