Black tip reef sharks are abundant in the Indian and Pacific Oceans.
Blacktip Reef sharks (Carcharhinus melanopterus) are one of the most common sharks found in the Indian and Pacific oceans. Their abundance makes them an important apex predator exerting top-down control – helping to structure inshore ecological communities.
Blacktip Reef sharks have small ranges and tend to be resident on specific home reefs and making short journeys to shallow sandy flats. Their tendency to reside on reefs and visit shallow waters makes them a popular ecotourism feature with opportunities to dive with them or see them from the shore.
While this might seem beneficial to all – providing localities with an incentive to protect Blacktip Reef shark populations (some populations have seen localised declines from overfishing) around 40% of shark sighting tours offer provision (shark feeding) as a way of interacting with these animals.
A two year study by Mourier, Claudet and Planes (2020) found that provisioning significantly changed C.melanopterus residency and habitat use patterns even when provision wasn’t present.
What do these finding mean? Well the authors suggest that this might reflect a wider issue with sharks that show a high degree of residency, that provisioning needs to be adapted and regulated to minimise its impact on behaviour and that further studies need to be carried out to find out how this shift in behaviour affects Blacktip Reef sharks’ general fitness at population levels. Beyond this I would also suggest that there needs to be some study of how the change in shark behaviour impact the structure of reef and sand flat ecological communities.
The article “Human‐induced shifts in habitat use and behaviour of a marine predator: the effects of bait provisioning in the blacktip reef shark” by J. Mourier, J. Claudet and S. Planes, 9 August 2020 is published in Animal Conservation available through the ZSL.
by Andrew Pollard