Effects of tourism-related provisioning on the trophic signatures and movement patterns of an apex predator, the Caribbean reef shark.

摘要

Wildlife provisioning, i.e. the provision of bait to generate aggregations of charismatic megafauna as tourist attractions, occurs around the world. This practice is often promoted as an economic incentive to conserve the focal species, yet has stimulated debate based on the potential for risks to human safety and perceptions of behavioural shifts in provisioned populations. We studied a population of Caribbean reef sharks (Carcharhinus perezi) in the Bahamas that has been subject to regular provisioning for >20 years. We used a combination of focal observations of sharks during feeding events, remote acoustic telemetry and stable isotope analysis of shark muscle tissue to determine the impacts of provisioning on the trophic signatures and ranging behaviour of sharks in this population. A small number of large sharks monopolised more than 50% of the bait on offer. These 'fed' individuals showed significant 15N enrichment in their tissues compared to conspecifics of the same size that failed to obtain bait at the feeding site, and un-provisioned sharks from a control site. Despite the disparity in trophic signatures, fed, unfed and control sharks exhibited similar degrees of residency at their respective home receiver sites, and travelled similar daily minimum distances. Thus, despite long-term provisioning of this Caribbean reef shark population, there is no evidence for shifts in the behaviours considered which might affect the ecological role of these sharks. However, further research is required to examine potential indirect effects of shark provisioning on sympatric fauna and habitat before this activity can be placed within a sustainable marine conservation framework.