Vol. 19: 245–254, 2013 ENDANGERED SPECIES RESEARCH Published online January 25 doi: 10.3354/esr00466 Endang Species Res Behavioural effects of whale-watching activities on an Endangered population of humpback whales wintering in New Caledonia Aline Schaffar1,*, Bénédicte Madon2, Claire Garrigue1, Rochelle Constantine3 1Opération Cétacés, BP 12827, 98802, Nouméa, New Caledonia 2The University of New South Wales, School of Mathematics and Statistics, Sydney, New South Wales 2052, Australia 3School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand 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 sin- uosity 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 popula- tion in New Caledonia, we suggest reinforcing management measures to increase the likelihood that the whale-watching industry is sustainable. KEY WORDS: Whale watching · Behavioural response · Disturbance · Sustainability · Management · Conservation Resale or republication not permitted without written consent of the publisher INTRODUCTION from commercial whaling by the International Whal - ing Commission (IWC) in 1966, illegal kills by the Over the last 2 centuries, Southern Hemisphere Soviet Union continued until 1972 (Clapham & humpback whales Megaptera novaeangliae were Ivashchenko 2009). This led to a population crash extensively hunted, reducing populations to a few of humpback whales in several areas, including percent of their pre-exploitation abundance (Chap- south of Australia, New Zealand and the South man 1974). Clapham & Baker (2002) estimated that Pacific Ocean (Clapham et al. 2009). Today, in con- over 200 000 Southern Hemisphere humpback trast with other stocks, Oceania humpback whales whales were killed during commercial whaling are recovering very slowly and are estimated at operations conducted between 1904 and 1980. Al - approximately 25% of their pre-whaling abun- though these whales were ostensibly protected dance (Constantine et al. 2012). As a result, Ocea- *Email: [email protected] © Inter-Research 2013 · www.int-res.com 246 Endang Species Res 19: 245–254, 2013 nia humpback whales were listed as Endangered in New Caledonia is one of the leading boat-based 2008 (IUCN 2008). whale-watch destinations in the South Pacific region The South Pacific Regional Environment Pro- (Schaffar & Garrigue 2007, Economists At Large gramme therefore considers threat reduction as a pri- 2008, Schaffar et al. 2010). Since its inception in 1995, ority for this stock (SPREP 2007). Humpback whales this industry has had an average annual growth rate wintering in New Caledonian waters represent one of 40% and involved 26 tour operators in 2008 of the smallest populations within Oceania, with only (unpubl. data). Considering the small number of 327 individuals (coefficient of variation = 0.11; Gar- humpback whales wintering in New Caledonia and rigue et al. 2004). Strong site fidelity (Garrigue et al. their slow recovery from past whaling operations, the 2002), combined with demographic and reproductive growth of whale-watching activities and the absence isolation (Garrigue et al. 2004, Olavarría et al. 2007), of management measures at the time of the study suggests that any threats on their breeding ground raised the question of the potential impact the pres- may further affect their recovery. ence of boats may have on the whales. A study was In recent years, watching whales in their natural initiated in 2005 to assess the behavioural responses habitat has developed as a valuable economic alter- of humpback whales to commercial and recreational native to whaling (Hoyt 2001, O’Connor et al. 2009) whale-watching boats, and to identify factors that and an important educational tool to raise public may influence such responses. This study also aimed awareness of the need for species and habitat protec- at identifying the level of the explanatory variables tion (Hoyt 2001). But without appropriate manage- likely to lead to a significant change in the whales’ ment, the presence of boats around cetaceans can behaviour. Information on factors affecting cetacean induce behavioural changes (e.g. Corkeron 1995, behaviour is critical to ensure that management Sousa-Lima et al. 2002, Williams et al. 2002, Constan- measures are adapted to each population and are tine et al. 2004, Foote et al. 2004, Scheidat et al. 2004, indeed efficient at minimising the impact of human Christiansen et al. 2010), and can therefore represent activities (Noren et al. 2009). a threat to the species exposed (IFAW 1999, Cor- keron 2004). Some of these behavioural responses may carry energetic costs to individuals (Williams et MATERIALS AND METHODS al. 2006) and cumulatively may have population- level effects (e.g. Bejder et al. 2006a). To date, most of Data collection these studies have been conducted on odontocetes, and studies on the impact of whale watching on mys- Between mid-July and mid-September 2005 to ticetes are scarce. 2007, observations were made from Cap Ndoua. This Following the worldwide trend, the whale-watch- lookout point is located 189 m above sea level over- ing industry throughout the South Pacific Islands looking the southern lagoon of New Caledonia, a region has demonstrated a remarkable growth of vast and open area with waters reaching up to 80 m 45% per annum since 1992 (Economists At Large in depth (Fig. 1). 2008). In particular, humpback whales, migrating Observations were conducted by a team of 3 every winter from Antarctica to their tropical breed- researchers and took place from early morning ing grounds, attract thousands of tourists and are the (around 07:00 h) to mid-afternoon (around 15:00 h) most popular species for tourism in the region during the time of year when humpback whales are (Orams 1999, Schaffar & Garrigue 2007, Economists present in the southern lagoon of New Caledonia At Large 2008). These small populations may be par- (July to September). Observations were restricted to ticularly at risk whilst on their breeding grounds, but days with no rain and a wind speed less than 15 quantitative data on the effects of tourism on the knots. endangered Oceania humpback whales are lacking. A Sokkia Set 5 theodolite was used to monitor the Since humpback whales fast during migration and on movement and behaviour of humpback whales in the their breeding grounds, they are limited in their abil- absence and presence of boats. The theodolite was ity to compensate for energetic costs potentially connected to a laptop computer running the tracking caused by a disturbance. If sufficiently high, these program ‘Cyclops’ (www.cyclops-tracker.com). This energetic costs could lead to females having to redi- program automatically transformed the vertical and rect energy from lactation to homeostasis for sur- horizontal coordinates from the theodolite readings vival, which could affect their long-term reproduc- into GPS points, and was used to record behavioural tive success. and fix data (i.e. whale breaths, boat identity), which Schaffar et al.: Whale watching and endangered humpback whales 247 for analysis when there were at least 5 surfacing bouts combined with a minimum of 20 min of observation, but lasted as long as required to obtain the 5 bouts. These tracks allowed a repre- sentative sample of the whales’ behaviour to be obtained. During tracks, the whales’ position was fixed with the theodolite once every minute. The fix was taken on the first adult whale to come to the surface after that time elapsed. We considered a group of whales to be 1 or more whales within 100 m of each other, generally moving in the same direction in a coordinated manner (Whitehead 1983, Mobley & Herman 1985). Group type was recorded at the start of each tracking session. Four categories of group type were used: singleton, pair of adult whales, groups of 3 or more adults and Fig. 1. Observation site and study area (limited to 8 nautical groups containing a mother−calf pair (alone or miles from the theodolite station to maximise tracking ac - accompanied by 1 or several escorts). A calf was curacy). The checked areas cannot be observed from the defined as an animal in close proximity to an adult shore station whale and visually estimated to be less than 50% of the length of the accompanying animal (Chittle- were verbally relayed by the theodolite operator to borough 1965). the computer operator. In order to minimise inter- If boats were present or arrived specifically to observer variability, the same person (A.S.) operated watch the whales within a 1000 m radius of the group the theodolite for all days of this study. being tracked, their position was recorded between Comparison of data collected from the land-based each fix of the group’s position. An observer tracked station and from boat-based surveys on the same the whales’ behaviour while the theodolite operator groups of whales showed overlapping tracks and fixed the position of boats.