Short-term impacts of daily feeding on the residency, distribution and energy expenditure of sharks

Tourism-related feeding of wildlife can result in detrimental, human-induced changes to the spatial distribution, social behaviour and health of target species. The feeding of sharks as part of shark-viewing activities has become increasingly popular in recent years to ensure reliable and consistent encounters. A common limitation in determining how feeding affects individuals or populations is the lack of baseline data prior to the establishment of a feeding site. Here, we documented the residency, spatial distribution, activity patterns and daily metabolic rates of juvenile lemon sharks, Negaprion brevirostris, prior to initiating daily feeding for 27 days to assess the effect of short-term feeding. We implanted acoustic transmitters equipped with accelerometers to record movement and activity in six lemon sharks. Sharks progressively anticipated the feeding events during the 27 days of daily feeding, as shown by a change in activity and increased time spent near the feeding site 1 h prior to feeding events. Shark behaviour did not fully return to baseline levels within the documented 90 days of postfeeding recovery. However, neither spatial distribution outside the refuge nor mean daily activity was affected by feeding. Sharks decreased their metabolic rates over the course of the study, but this was probably due to falling water temperature rather than the effect of feeding. Overall, our study shows that anticipatory behaviour in juvenile lemon sharks can occur within 11 days of daily feeding events, but behavioural changes seem confined to fine-scale movement patterns and may not affect these sharks’ daily energy needs. The ability to assess the effects of daily feeding at a site where tourism has not been occurring previously provides new information for operators and managers of wildlife tourism to account for and minimize potentially detrimental effects on the target species.