In-water encounters with Humback Whales has Significant Effect on Behavioural Patterns

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A new research paper has been published investigating the effects of swimming with humpback whales during the breeding season in Tonga. Lead author, Lorenzo Fiori, is naturalist guide of WCA Partner TERRA AZUL.

The Kingdom of Tonga is one of the only countries worldwide which allows tourists to get into the water with these whales. The study conducted in this paper found evidence that these activities do have a significant effect on the time taken in each behavioural state for the humpback whales.

It was observed that in areas of high human interaction, mother humpback whales would spend less time nurturing her calf and more time in a travelling state. This causes her to utilise energy reserves which would otherwise be spent on ensuring her calf is as healthy as possible.

On top of these effects for the whales, the behavioural responses can place danger upon the human swimmers in the water with the marine mammals.

Read more here:

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


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.


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