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Vertical take‐off and landing (VTOL) unmanned aerial vehicles (UAVs) are becoming invaluable data collection platforms for cetacean research. In particular, multi‐rotors can be used to measure whales and investigate their behavior. Moreover, VTOL UAVs are increasingly accessible for recreational and commercial pilots, and close encounters with whales are widely documented. Unfortunately, quantitative assessments of potential disturbance for the targeted animals are not yet published and guidelines for responsible use of UAVs around cetaceans are still under development. We conducted VTOL UAV surveys on humpback whales in Vava'u, Kingdom of Tonga. Interestingly, whale behaviors such as socializing and nurturing were not detected by trained observers on board the research vessel, but were evident from the UAV. Nevertheless, no significant differences were detected in diving and swim parameters between absence and presence of UAV flying at 30 m altitude. These results suggest that VTOL UAVs can be a noninvasive tool to gather morphometric and behavioral data on baleen whales. However, further research is necessary to establish whether applications that require flight altitudes lower than 30 m and targeting different species may elicit behavioral responses. [ABSTRACT FROM AUTHOR]

Vava’u, Kingdom of Tonga, is a well-established whale-watching destination in the South Pacific. Between July and October, the waters around the archipelago represent one of the most important breeding grounds for Oceania humpback whales (Megaptera novaeangliae). The Tongan government allows tourist swimming activities with whales and tour operators strongly promote the practice of swimming-with-whales, focusing primarily on mother-calf pairs. However, there is increasing evidence, derived from empirical research on swim-with-cetacean tourism, that this kind of interaction affects cetacean behaviour and can lead to negative effects on the cetaceans involved. This study represents the first assessment of humpback whales’ behavioural responses to vessel and swimmer approaches in Vava’u. Fifty-six surveys took place during the 2016 and 2017 whale breeding seasons aboard dedicated research and tour vessels. Whale dive time, number of reorientation events, and respiration rates were documented in both the absence and presence of boats and swimmers. Vessel approach type, swimmer placement, and whale avoidance responses were also recorded. Results indicate that the average diving time and the proportion of time spent diving in the presence of swimming activities increased significantly for mother-calf pairs (F2 , 36 = 18.183, P < 0.001; F2 , 36 = 5.462, P = 0.009, respectively). Moreover, avoidance responses of whales towards tour vessels were observed for one third of vessel approaches (33.5%) and the avoidance rate was significantly affected by the boat approach type (95% CI: 20.7–69.2%, z = 3.50, P < 0.001). Finally, low levels of compliance to the existing Tongan swim-with-whales regulations were documented, in particular the stipulated whale resting time between interactions with tour operator vessels and swimmers was often not respected (38.4%). Vava’u is an important calving ground for the Oceania humpback whale population and these findings should be carefully considered by stakeholders in Tonga and at other locations where swim-with-whales opportunities are being undertaken. Effective strategies to reduce the risk of detrimental effects on the whales targeted by swimming activities, especially mother-calf pairs, are needed. [ABSTRACT FROM AUTHOR]