Assessing and Mitigating Humpback Whale (Megaptera Novaeangliae) Disturbance of Whale-watching Activities in Reunion Island

Abstract

Whale-watching, including swim-with-whales activities, is developing at an enormous rate in Reunion Island. This is raising concerns about its impacts on breeding humpback whales and challenging the sustainability of the activity. In 2017, a dedicated at sea patrol team, “Quietude” was created to observe, monitor and sensitize whale watchers at sea in order to improve compliance with local guidelines. In this context, the team assessed whale-watching in Reunion Island during two humpback whale breeding seasons in 2017 and 2018, between June and October. Sighted groups were mostly composed of mother/calf pairs spending most of their time resting near or at the surface. Whale-watching vessels were present in 85.1% of sightings, of which 68.4% were recreative. Swim-with-cetaceans activities were very frequently observed in 42% of sightings. Overall, compliance with the charter was as high as 68% of whale sightings with vessels/swimmers were in line with the recommendations. However, low compliance (32.8%) was observed with the specific recommendations of swim-with-cetaceans activities. Swimmers were reported in active groups displaying agonistic behaviors, which poses evident human safety concerns. Humpback whale resting and nursing behaviors were disrupted significantly by whale-watching activities. Humpback whales tended to avoid vessels and swimmers, especially when their behavior was intrusive or not compliant with the charter. Positive humpback whale responses were more likely to occur if the charter’s recommendations were not breached. Our results highlight how a non-binding regulation, with recommendations scrupulously pursued, allows for a reduction in whale-watching disturbances and supports a better tourism experience. Our results advocate for reinforcing tourism education, whale-watching adaptive management and regulations, specifically for vulnerable groups with a calf and for the swim-with-whales activities. This could be efficiently achieved by engaging all stakeholders and the permanent team on the field “Quietude” to enhance dissemination of best practices and sensitivity around sustainable values of implemented regulations.

Dolphin Watching and Compliance to Guidelines Affect Spinner Dolphins’ (Stenella longirostris) Behaviour in Reunion Island

“…Finally, the particularity of the whale- and dolphin-watching activity in Reunion Island is that approximately half of the vessels are for recreational uses (e.g., rented [ 31 , 46 ]). Encouraging education and awareness-raising campaigns is essential to inform the local communities and tour operators about the impacts of the activity, the best practices and the changes in the regulations [ 9 , 21 , 46 , 56 , 81 ]. Nonetheless, in Reunion Island, underwater interactions also take place [ 34 ], whose short-term effects have been widely reported worldwide [ 20 , 22 , 51 , 82 ].…”

“…The recent regulations comprise both hard (prefectural decree) and soft (code of conduct) laws, contributing to a fragmented legal framework at the regional scale and discontinuous protection of cetaceans from one territory to another within the western Indian Ocean [ 44 ]. While several studies exist on the ecology and distribution of the dolphin populations of Reunion Island [ 32 , 35 , 36 ], few have focused on the impacts of cetacean watching, and those few studies have concentrated on impacts on humpback whales [ 45 , 46 ]. This study aims to assess for the first time the effects of dolphin watching on spinner dolphins’ behaviour through a focal follow instantaneous scan sampling approach.…”

The Behavioural Impacts of Commercial Swimming With Whale Tours on Humpback Whales (Megaptera novaeangliae) in Hervey Bay, Australia

“…Off Western Australia, migrating humpback whales adopted both horizontal and vertical avoidance strategies in response to swim-with-whale activities by increasing their swim speeds, swimming more erratically, changing their heading away from the vessel and altering their dive patterns (Sprogis et al, 2020). Likewise, off Reunion Island, humpback whales were less likely to continue resting when swimmers were in the water (Hoarau et al, 2020). Impacts from swim-with-whale tourism likely differ from typical whale watch tourism, due to closer vessel approaches to the whales to place swimmers in the water and the presence of swimmers in the water.…”

“…Examining the short-term behavioural responses of humpback whales to swim-with-whale activities across different locations and with differing approach types from operators is of importance as swimming with these large whales poses risks to the safety of humans. Dangerous encounters between humpback whales and humans have been documented off Western Australia, Réunion Island and the Kingdom of Tonga (Fiori et al, 2019;Barra et al, 2020;Hoarau et al, 2020;Sprogis et al, 2020). These agonistic behaviours include tail fluke thrashes, peduncle throws and pectoral fin slaps (Sprogis et al, 2020).…”

“…Swimmers have sustained injuries such as broken bones, bruises, and scratches (Fiori et al, 2019;Sprogis et al, 2020), generally from pectoral shears and fluke thrashes, which are common behaviours directed toward swimmers by humpback whales (Barra et al, 2020). Safety incidents have occurred while swimming with mother and calves (Barra et al, 2020;Hoarau et al, 2020), where either the mother or the calf can cause an injury to swimmers. Thus, due to the high-risk of human injuries it is important to manage the industry correctly to ensure the safety of swimmers.…”