The Mistaken Identity Hypothesis (MIH) interprets shark bites on surfers, swimmers and snorkelers as ‘mistakes’ stemming primarily from similarities in the visual appearance of ocean users and the sharks typical prey. MIH is now widely accepted as fact by the general public and some sections of the scientific community despite remaining unproven. This hypothesis assumes that ‘mistaken’ shark bites on humans result primarily from confusing visual cues and ignores the important role of other senses (e.g. hearing) in discriminating potential prey. A far simpler ‘natural exploration’ hypothesis can reasonably explain not only shark bites that have been characterized as ‘mistaken identity’ events but also those that cannot be reasonably explained by MIH (e.g. shark bites that occur in very clear water). Simply stated, sharks don’t make ‘mistakes’ but instead continually explore their environments and routinely investigate novel objects as potential prey by biting them.
Recent studies suggest sharks cognitive abilities are comparable to other vertebrates such as mammals and birds, but we still know relatively little about the long-term memory capacity of sharks. We took advantage of the COVID-19 anthropause to determine whether bull sharks conditioned at a provisioning ecotourism site in Fiji would remember the site after an 18-month hiatus in shark feeding activities. We hypothesized that if bull sharks remembered the food rewards associated with divers at the site, they would return to the reactivated site more rapidly than the original recruitment process that occurred when the site was first established in, 2015. We assumed that original recruitment to the newly established site represent a period of learning and conditioning, whereas a significantly faster recolonization of the site would imply memory recall of the original conditioning. We monitored bull shark abundance at the site for three years (1018 dives) from its original establishment in 2015 until all feeding and diving activities were ceased for 18 months in December, 2020. When shark feeding resumed, we documented bull sharks returning to the site over a three-week period (45 dives beginning June 22, 2022) and compared observed abundances with modelled predictions assuming no interruption to provisioning. Results revealed a rapid return to ‘business as usual’, suggesting that bull sharks still remembered the food reward conditioning despite an 18-month hiatus in provisioning. This supports the existence of long-lasting cognitive capacities in this species and highlights their relevance for managing activities that could disrupt their natural ecology.
Although many animal species demonstrate individual personalities, studying these traits in wild sharks has proven challenging. Past research focused mainly on captive or juvenile sharks. Our ethological study of 31 wild adult bull sharks (Carcharhinus leucas) utilized an artificial provisioning site, amassing 2813 observations over 651 dives from October 2015 to January 2018 (27 months). Behavioural traits, including boldness-shyness and aggressiveness-placidity, were assessed using an ad hoc ethogram and an influencing factors table. This innovative approach not only allowed us to characterize individual shark behaviours but also to quantify their changes over time. Our findings suggest that adult bull sharks likely possess distinct personalities, spanning from extreme shyness to pronounced boldness, with varying levels of plasticity among individuals. Further exploration of shark personalities holds promise for advancing our comprehension of human–shark interactions and refining the management of potential aggressive behaviours exhibited by large shark species toward humans.