New research papers on the impact of tourism on humpback whales

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WCA International Whale Watching Review Panel member Kate Rose-Ann Sprogis and colleagues have just published two new research papers looking at the impact of tourism on humpback whales. Specifically the behavioural responses to swim-with activities and vessel noise level.

This fascinating and vital research has important implications on how guidelines should regulate cetacean based tourism in the future. Guidelines for whale watching tourism rely on good quality research to support them and so we are thrilled that Kate is a member of our advisory panel to review WCA Certified Responsible Whale Watching Operators applications and refine our certification programme.

Kate Sprogis, Simone Videsen, Peter Madsen (2020) Vessel noise levels drive behavioural responses of humpback whales with implications for whale-watching.


Disturbance from whale-watching can cause significant behavioural changes with fitness consequences for targeted whale populations. However, the sensory stimuli triggering these responses are unknown, preventing effective mitigation. Here, we test the hypothesis that vessel noise level is a driver of disturbance, using humpback whales (Megaptera novaeangliae) as a model species. We conducted controlled exposure experiments (n = 42) on resting mother-calf pairs on a resting ground off Australia, by simulating whale-watch scenarios with a research vessel (range 100 m, speed 1.5 knts) playing back vessel noise at control/low (124/148 dB), medium (160 dB) or high (172 dB) low frequency-weighted source levels (re 1 μPa RMS@1 m). Compared to control/low treatments, during high noise playbacks the mother’s proportion of time resting decreased by 30%, respiration rate doubled and swim speed increased by 37%. We therefore conclude that vessel noise is an adequate driver of behavioural disturbance in whales and that regulations to mitigate the impact of whale-watching should include noise emission standards.

Sprogis KR, Bejder L, Hanf D, Christiansen F. 2020. Behavioural responses of migrating humpback whales to swim-with-whale activities in the Ningaloo Marine Park, Western Australia.


Swim-with-whale tourism is a lucrative and rapidly growing industry worldwide. Whale-watching can cause negative effects on the behaviour of targeted animals. Although this is believed to be particularly true for close-up interactions, such as swim-with operations, few empirical studies have investigated this. In 2016, the Western Australian State Government commenced a swim-with humpback whale (Megaptera novaeangliae) trial in the Ningaloo Marine Park, where 11 commercial licences were granted. The swim-with trial was conducted during both the northern and southern whale migration (August to November), during which we assessed potential short-term behavioural effects on humpback whales to swim-with activities. From both an independent research vessel (n = 300 h) and on-board commercial swim-with vessels (n = 357 h), we collected group-follow data (n = 224) on whale behaviour beforeduring and after swim-with activities. Behavioural effects on whales were investigated, including movement patterns (deviation and directness index, heading, swim speed), surfacing patterns (dive duration and respiration rate) and occurrence of agonistic behaviours. Results showed that the most common type of vessel approach to place swimmers in the water was in the path of whales (89.8% of interactions). During in-path approaches, vessels travelled significantly faster (P = .002) compared to when approaching from the side (side/line abreast approaches). When vessels approached in the whales’ path, whales exhibited horizontal and vertical avoidance strategies by adopting a less predictable path (deviating from 32° to 46°), increasing turning angles away from the vessel (heading from 73° to >90°), increasing swim speeds (from 1.68 to 1.89 ms−1), and decreasing the duration of their dives (from 224 to 194 s). Whales displayed a higher frequency of agonistic behaviours when a swim-with vessel was <100 m distance from them compared to >100 m away (P = .011). Young-of-year calves were present during 19.6% (18 of 92) of group-follows that included swim attempts. To reduce potential impacts on whales and increase swimmer safety, we recommend to avoid in-path vessel approaches, not place swimmers in the water with groups of whales that perform agonistic behaviours, and avoid swimming with young-of-year calves.

Sophie Lewis
Author: Sophie Lewis

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