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Environmental and anthropogenic factors affecting the increasing occurrence of shark-human interactions around a fast-developing Indian Ocean island (vol 8, 2018)

Authors
  • Lagabrielle, Erwann
  • Allibert, Agathe
  • Kiszka, Jeremy J.
  • Loiseau, Nicolas
  • Kilfoil, James P.
  • Lemahieu, Anne
Publication Date
Jan 01, 2018
Source
HAL-INRIA
Keywords
Language
English
License
Unknown
External links

Abstract

Understanding the environmental drivers of interactions between predators and humans is critical for public safety and management purposes. In the marine environment, this issue is exemplified by shark-human interactions. The annual shark bite incidence rate (SBIR) in La Réunion (Indian Ocean) is among the highest in the world (up to 1 event per 24,000 hours of surfing) and has experienced a 23-fold increase over the 2005-2016 period. Since 1988, 86% of shark bite events on surfers involved ocean-users off the leeward coast, where 96% of surfing activities took place. We modeled the SBIR as a function of environmental variables, including benthic substrate, sea temperature and period of day. The SBIR peaked in winter, during the afternoon and dramatically increased on coral substrate since the mid-2000s. Seasonal patterns of increasing SBIR followed similar fluctuations of large coastal shark occurrences (particularly the bull shark Carcharhinus leucas), consistent with the hypothesis that higher shark presence may result in an increasing likelihood of shark bite events. Potential contributing factors and adaptation of ocean-users to the increasing shark bite hazard are discussed. This interdisciplinary research contributes to a better understanding of shark-human interactions. The modeling method is relevant for wildlife hazard management in general. Human-wildlife conflicts result from the negative impacts of interactions between wild animals and people. Mitigating human-wildlife conflicts is a growing challenge, particularly since the spatial and temporal overlap between wildlife and humans is increasing 1-3. Understanding the environmental drivers of these interactions is critical for public safety and management 2,3. In several cases, conflicts between different public interests can arise, and human-wildlife conflicts can adversely affect economic activities 1. In the marine environment, this issue is exemplified by growing concerns surrounding shark bites on ocean-users 4. Over the past three decades, the number of unprovoked shark bites on humans has increased around the world, creating numerous challenges for coastal management policies 4. This increasing trend has been documented in multiple countries 5 , and has been anecdotally linked to increasing recreational activities 6 , particularly surfing 5,7,8. Despite receiving large amounts of media and public attention, shark bites remain relatively rare events 9 .

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