Effects of whale-based tourism in Vava’u, Kingdom of Tonga: Behavioural responses of humpback whales to vessel and swimming tourism activities

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.

瓦瓦乌，作为汤加王国的知名观鲸胜地，位于南太平洋地区。在七月至十月期间，该群岛周围水域成为大洋洲座头鲸（Megaptera novaeangliae）最重要的繁殖地之一。汤加政府允许游客进行与鲸鱼共游的活动，且旅游运营商大力推广这一行为，主要聚焦于母鲸及其幼崽。然而，越来越多的实证研究表明，这种互动会影响鲸类的行为，并可能导致参与鲸类的负面影响。本研究首次评估了瓦瓦乌地区座头鲸对船只和游泳者接近行为的反应。2016年和2017年鲸鱼繁殖季节，在专用科研和旅游船只上进行了五十六次调查。记录了鲸鱼潜水时间、转向事件数量以及呼吸频率，这些记录在船只和游泳者存在与否的情况下均已完成。同时，还记录了船只接近类型、游泳者位置以及鲸鱼回避反应。结果显示，在游泳活动存在的情境下，母鲸及其幼崽的平均潜水时间以及潜水时间占比显著增加（F2,36 = 18.183，p < 0.001；F2,36 = 5.462，p = 0.009）。此外，在船只接近的三分之一情况下（33.5%）观察到鲸鱼对旅游船只的回避行为，且回避率受到船只接近类型的影响（95% CI：20.7 – 69.2%，z = 3.50，p < 0.001）。最后，记录到对现有汤加与鲸鱼共游规定的遵守程度较低，尤其是与旅游运营商船只和游泳者互动之间的鲸鱼休息时间规定往往未能得到尊重（38.4%）。瓦瓦乌是太平洋座头鲸种群的重要产崽地，这些发现应引起汤加以及其他开展与鲸鱼共游机会的地区利益相关者的密切关注。需要有效策略以降低游泳活动对目标鲸类，尤其是母鲸及其幼崽，造成不利影响的潜在风险。