Using Unmanned Aerial Vehicles (UAVs) to assess humpback whale behavioral responses to swim-with interactions in Vava’u, Kingdom of Tonga

Abstract

The Kingdom of Tonga is a one of the few countries worldwide that allow swim-with-whales tourism activities. Most of the tour operators are based in Vava’u archipelago which represents an important breeding ground for Oceania humpback whales (Megaptera novaeangliae). This study represents an assessment of the effects of swimmer approaches on humpback whales’ behaviour using Unmanned Aerial Vehicles (UAVs). UAV flights took place during the 2016 and 2017 whale breeding seasons from onboard research and swim-with-whales vessels. Whales’ behavioural states (resting, travelling, surface-active, socialising, nurturing) were assessed from aerial videos and the proportions of time spent in each state in the presence and absence of swimmers were compared. Whale agonistic behaviours directed towards swimmers and the injury of a swimmer caused by a whale were documented. Results indicate that in-water tourism activities significantly altered the time spent in each behavioural state by humpback whale in Vava’u. Mother-calf pairs decreased the proportion of time spent nurturing, while the time spent travelling increased two-fold when approached by swimmers. These findings indicate a potential energy expenditure increase for humpback whale mothers and their calves in response to swim-with tourism activities in Vava’u. Moreover, whales’ behavioural responses can pose danger of injury to swimmers.

Keywords:

• behaviour
• drones
• impact
• injury
• swim-with-whales

Acknowledgments

The authors thank the Tongan Ministry of Tourism and Ministry of Fisheries for their logistic support and project endorsement. Special mentions go to Miss Anaseini ‘Otumuli of the Ministry of Tourism for her timely and precious assistance in obtaining the necessary authorisations for this study and to Dr Semisi Taumoepeau for his help in the permit application process. Special thanks are owed to Barbara Lësser, Courtney Burk, Craig Koning, field assistants, and skipper. Our acknowledgements are extended to Ashray Doshi for assistance with the UAV operations, Dr Martin Bader, Dr Daniel Breen, and Graham Hinchliffe for assistance with data analysis and experimental design. Finally, the authors thank the School of Science and Auckland University of Technology for providing the field equipment and logistics. UAV operations were conducted under the research permit MOT-4/3 issued by the Tongan Ministry of Tourism. As Tonga lacked specific laws regarding the use of UAVs in its national airspace in 2016 and 2017, operations complied with New Zealand Civil Aviation Authority (CAA) regulations. The primary researcher operated the UAV and holds a Remote Pilot Certificate (license no. 839465) issued by the Australian Civil Aviation Safety Authority (CASA).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

LF conceived the research design and statistical approach, conducted data collection, analysed the data, and wrote the manuscript; EM, MO, and BB helped conceive and plan the research design and they each edited the manuscript.