Behavioural effects of whale-watching activities on an Endangered population of humpback whales wintering in New Caledonia

Abstract

After decades of whaling, Oceania humpback whales Megaptera novaeangliae have such a low rate of recovery that a trend is not currently measurable. They are listed as Endangered by the IUCN, and any possible threat to the whales needs to be carefully monitored and mitigated. Whale-watching activities represent an important economic development throughout the South Pacific but also carry a potential risk of impact for these recovering populations. New Caledonia is among the leading countries for humpback whale watching in Oceania. Land-based theodolite observations were conducted between 2005 and 2007 to assess the effect of boats on humpback whale behaviour in New Caledonia. Natural experiments were used to investigate the response of whales to boat approaches, and opportunistic observations were used to assess which variables best described variability in behaviour. Over 80% of whales approached by boats significantly changed their behaviour. Changes in path predictability (directness and deviation index) were most commonly affected and are likely to represent an efficient and low-cost avoidance strategy. Linear models showed that as boats get closer, humpback whales significantly increased the sinuosity of their path. The threshold for such a response corresponded to an approach distance of 335 m. Based on these results and considering the vulnerability of the humpback whale population in New Caledonia, we suggest reinforcing management measures to increase the likelihood that the whale-watching industry is sustainable.

Effects of boats on the surface and acoustic behaviour of an endangered population of bottlenose dolphins

“…Although many cetacean studies have documented increased speeds and direction changes in response to the presence of boats (e.g. Nowacek et al 2001, Williams et al 2002, Lemon et al 2006, Schaffar et al 2013, no such changes were detected in this study. This could be related to tour boats in Doubtful Sound generally travelling at very slow speeds (x = 2.9 knots, CV = 1.1) while within 200 m of the dolphins.…”

“…Miller et al 2008, Stamation et al 2010) and movement patterns (e.g. Nowacek et al 2001, Stensland & Berggren 2007, Schaffar et al 2013. Although several studies have investigated the effects of boats and associated noise on the animals' acoustic behaviour, this aspect of behavioural response and its implications still remain poorly understood.…”

Effects of whale watching on the activity budgets of humpback whales,Megaptera novaeangliae(Borowski, 1781), on a feeding ground

“…The area of interaction between whales and vessels (including commercial and private recreational vessels) was defined as the 500‐m radius around the whale. This was chosen based on previous whale‐watching studies on humpback whales, which used a radius ranging between 300 m (Corkeron, ; Morete et al, ) and 1000 m (Gulesserian, Slip, Heller, & Harcourt, ; Schaffar et al, ). Therefore, an intermediate distance of 500 m seemed reasonable and was chosen for the present study.…”

“…Whale‐watching activities occur both in the breeding (Avila, Correa, & Parsons, ; Morete, Bisi, & Rosso, ; Schaffar, Madon, Garrigue, & Constantine, ) and the feeding (Boye et al, ) grounds of whales. In the feeding grounds of SEAK, whales feed on abundant prey resources, including: Pacific herring, Clupea pallasii Valenciennes, 1847; capelin, Mallotus villosus (Müller, 1776); and euphasiids, primarily Euphausia pacifica , Hansen, 1911 (Chenoweth, Gabriele, & Hill, ; Dolphin, ).…”

Evaluating the potential disturbance from dolphin watching in Lovina, north Bali, Indonesia

“…The presence of tour boats may alter the path of travel (Williams and Ashe ) and even force the animals to dive to avoid the boats (Schaffar et al . ). Interactions with dolphin watching boats may also decrease time spent foraging (Christiansen et al .…”