Environmental and anthropogenic factors affecting the increasing occurrence of shark-human interactions around a fast-developing Indian Ocean island

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.

Population structure, connectivity, and demographic history of an apex marine predator, the bull shark Carcharhinus leucas

“…The bull shark Carcharhinus leucas is caught in recreational, subsistence, and targeted commercial fisheries, as well as bycatch throughout its range (Aguilar et al, ; Almeida, McGrath, & Ruffino, ; Bonfil, ; Branstetter & Stiles, ; Clarke, Magnussen, Abercrombie, McAllister, & Shivji, ; Doukakis et al, ; Temple et al, ). In several locations, the bull shark has also been the subject of lethal risk reduction programs due to attacks on humans (Cliff & Dudley, ; Dudley, ; Dudley & Simpfendorfer, ; Lagabrielle et al, ). This high‐trophic level predator inhabits warm temperate and tropical waters worldwide, and plays an important role in coastal and estuarine ecosystems (Daly, Froneman, & Smale, ; Matich, Heithaus, & Layman, ; Trystram, Rogers, Soria, & Jaquemet, ).…”

Coexisting with sharks: a novel, socially acceptable and non-lethal shark mitigation approach

“…Indeed, shark mitigation strategy preference analysis by Simmons and Mehemet 22 concluded that the likelihood of harm to sharks and other marine species is a central reason for community preferences. Several studies highlight the dilemma faced by managers tasked with mitigating dangerous shark incidents, and the reliance on established strategies that offer perception, but limited evidence, of risk reduction 6,10,49,50 . Respondents in our study were casual beachgoers who use the near-shore area for recreation.…”

Impact of the Use of a Teaching Toolbox in an Awareness Campaign on Children's Representations of Coral Reefs

“…In addition, local context or time circumstances may exacerbate a strong fascination, fear and imagination about the species, in particular, in our case, following an accident caused by a shark just before our intervention in the school and relayed in the media. This phenomenon was observed several times in Reunion in different classes involved in the research program where children drew sharks, the island having been impacted recently by several successive shark accidents (Lagabrielle et al, 2018).…”