BRUVs recordings of blacktip reef and lemon sharks in Tetiaroa

There is growing evidence of the important role learning plays in shark foraging, but few studies have examined the relationship between learning and foraging behaviour in free-living settings. We addressed this knowledge gap by experimentally contrasting responses of blacktip reef (Carcharhinus melanopterus) and sicklefin lemon (Negaprion acutidens) sharks to an olfactory-only feeding stimulus – baited remote underwater video stations (BRUVS) – that was either offered repeatedly at the same location or spatially randomized throughout the lagoon of Tetiaroa, French Polynesia. Blacktip reef sharks exhibited behaviour consistent with the hypothesis that cue predictability fosters spatial associative learning, exhibiting increasing relative abundance upon introduction of the cue (MaxN at deployment) and decreasing arrival times as the experiment progressed, whereas sicklefin lemon sharks showed no evidence of varying responses to cue treatment type over time. Accordingly, our findings advance our understanding of shark cognition by highlighting that spatial associations can develop in response to stable feeding cues even when the olfactory attractant is not accompanied by a reward, while also indicating that shark responses to anthropogenic feeding cues can be species-specific. They also suggest that, for at least some shark species, olfactory cues alone could lead to habituation that confounds non-invasive efforts to monitor shark populations and communities (e.g., with BRUVS) and drive spatial associations with the potential to promote both ecotourism and negative human-shark interactions.