Scientific Literature: Searchable Database

This report provides a comprehensive account of interactions with dwarf minke whales by swimming-with-whales (SWW) endorsed vessels in the Cairns/Cooktown Management Area of the Great Barrier Reef Marine Park over the period 2003 to 2008. Results presented in this report are primarily based on analyses of Great Barrier Reef tourism industry-collected Whale Sighting Sheets. Key management processes and outcomes, arising from bi-annual stakeholder workshops (held pre- and post-season) during the 2003–2008 Great Barrier Reef Marine Park Authority-funded Dwarf Minke Whale Tourism Monitoring Program are also summarised and discussed. During the latter three years of this program, three PhD studies (by Mangott, Sobtzick and Curnock) contributed significantly to our knowledge of this unique aggregation of dwarf minke whales, their interactions with humans in the Great Barrier Reef Marine Park and the sustainable management of these interactions. Some of the key findings of these three PhD studies are included in this report. Over the six year period, 90% (1334/1477) of reported Great Barrier Reef dwarf minke whale encounters occurred during June and July. The greatest level of interaction occurred in the Ribbon Reef 9/10 Area, which accounted for more than two-thirds (66.9%; 1388/2074 hours) of the total reported encounter time for the Great Barrier Reef Marine Park for the study period. Encounters at a single dive site known as ‘Lighthouse Bommie’ (a small and relatively isolated coral pinnacle in the vicinity of Ribbon Reef 10; 14o 52.5’S, 145o 41.3’E) represented over a third (36.4%) of the total encounter time for the entire Great Barrier Reef. The number of encounters at Lighthouse Bommie and in the Ribbon Reef 9/10 Area increased substantially over the six seasons (Lighthouse by 129%, from 24 to 55 encounters; Ribbon 9/10 Area by 121%, from 81 to 179 encounters), however the mean duration of encounters for these locations showed no discernable trends or significant differences. The total interaction time with dwarf minke whales nearly doubled over the six-year reporting period (90% increase 2003-2008), with this growth occurring primarily in the Ribbon Reefs and in the Ribbon Reef 9/10 Area in particular. It is considered that this trend is an indication of increasing industry ‘effort’ by the SWW-endorsed live-aboard vessels, which have increased their use of dive sites in areas where dwarf minke whales are more likely to be encountered (e.g. Lighthouse Bommie and nearby sites). This increasing effort was confirmed in the PhD study by M. Curnock (Curnock, 2010) which analysed industry effort data that was provided voluntarily by the SWW-endorsed operators. With only 6% (89/1477) of Whale Sighting Sheets submitted by non-SWW-endorsed vessels and 2% (16/782) of encounters in the Ribbon Reef 9/10 Area reported by non-SWW-endorsed vessels, it is clear the growth trend is attributable to the same few SWW-endorsed live-aboard operations that regularly access the Ribbon Reefs and their shift in effort to sites with higher whale encounter rates. Based on an analysis of the status of the vessel when a dwarf minke whale encounter was initiated, it is clear that the whales were initiating approaches to the vessels. Encounters are defined as a sighting and/or interaction with one or more whales, during which an in-water interaction (where divers or snorkelers are present in the vicinity of a whale) may or may not eventuate. Over the six seasons, 73% (1062/1447) of encounters were initiated when the vessels were not underway (either anchored or moored). Of the total encounters reported by vessels in the Great Barrier Reef, 64% (949/1475) resulted in an in-water interaction. For 87% (824/949) of in-water interactions, a rope was deployed from the vessel for use by snorkelers and/or scuba divers. The PhD study by S. Sobtzick (Sobtzick, 2010) involved the identification and cataloguing of individual whales over three minke whale seasons (2006–2008). This study drew upon a broad sightings network involving photos and video footage donated by 13 different vessels, providing valuable biological information about within and between season re-sightings and residence times 2 of individual whales. Her study reports that more than one-third of all completely identified whales were resighted within each season (for 2006 and 2007), which indicates that the interacting population is smaller than expected from previous, less comprehensive studies such as Birtles et al. (2002). An initial population estimate for the interacting Great Barrier Reef dwarf minke whale population is included in the PhD study (Sobtzick, 2010). Low mean residence times (8 days in 2006 and 10 days in 2007) suggest that the interacting population is open (i.e. subject to immigrations and emigrations during the season). The high proportion of within-season resightings and long encounter times (the overall mean in-water interaction duration from the WSS was 120 minutes) potentially result in high cumulative interaction times for some individual dwarf minke whales with vessels. This raises concerns about cumulative impacts on these whales, especially among those highly interactive individuals. Sobtzick’s PhD study also used videogrammetry to provide accurate length estimates of individual whales. This study found that while every size class of whale (including calves, juveniles and sexually mature animals) was present over the course of a season, the majority of dwarf minke whales interacting with the primary research vessel Undersea Explorer in 2006 (63%) and 2007 (65%) were sexually immature. The PhD study by A. Mangott (2010) investigated the behaviour of interacting dwarf minke whales around vessels and swimmers. This study showed that the whales voluntarily initiate and maintain contact with vessels for prolonged periods of time and not only show a clumped distribution around vessels (<60m from the vessel), but actually aggregate around swimmers. The whales’ voluntary initiation and maintenance of close contact for prolonged periods contrasts with most wildlife-human interactions where the wildlife either tolerate humans and/or show no interest in interacting with people unless there is a more tangible benefit, such as food. The behaviour of interacting dwarf minke whales was shown to change over time. The passing distance to swimmers decreased significantly during an in-water interaction, and this response was more pronounced in whales belonging to a large group (NB. The mean number of whales for in-water interactions reported in the WSS was 3.7; estimates ranging from 1 to >25). Passing distances of re-sighted dwarf minke whales were significantly less in subsequent interactions (by a mean of 1.5m) than for their first recorded in-water interaction. Thus the more familiar the whales were with the stimulus (i.e. resighted individuals) the more inquisitive the whales behaviour appeared to be. Mangott assessed the risks associated with a range of dwarf minke whale behaviours, to both the whales and swimmers, in relation to their proximity of occurrence. The immediate overall risk of harm to the swimmers and/or the whales for the majority of the dwarf minke whale behaviours is regarded as low for both the swimmers and the whales. However, highly interactive whales that make very close approaches (defined as <1m) to humans and objects (e.g. ropes) are at a greater risk of causing harm to humans and/or themselves (e.g. from physical contact with swimmers, objects and/or entanglements in ropes). Most behaviours that were considered to pose a risk of harm to swimmers were displayed by only few known, individual whales. Mangott interviewed 21 expert key informants (including cetacean scientists and managers; 60% of whom had previously seen dwarf minke whales and all of whom had expertise on cetacean biology or their management) to evaluate these risks and assess their views and concerns about the management of the SWW activity. The current view of most Key Informants about the conduct of the Great Barrier Reef SWW activity was positive, however respondents expressed concerns for longer-term cumulative impacts on the whales (e.g. disruption of important behavioural states and negative influences on time-activity budgets), potential industry expansion and the potential for discontinuation of research and monitoring of the activity. To ensure that the SWW activity is managed sustainably, the Key Informants agreed that the activity requires (a) continuous monitoring and (b) further studies to identify potential long-term impacts and address key knowledge gaps (e.g. migration, population parameters). The PhD study by M. Curnock (submitted 2010) investigated mechanisms for assessing the sustainability of the SWW activity. Outcomes of the study included the identification and 3 evaluation of a range of sustainability indicators (based on sustainability objectives that were developed collaboratively with key stakeholders) and the assessment of industry-generated data for cost-effective sustainability monitoring. Surveys of passengers on board the SWW endorsed vessels (n=2,171) revealed significant differences between live-aboard operations and day-trips, including a much lower proportion of day-boat passengers experiencing in-water interactions with minke whales (17% compared to 97% of live-aboard passengers). Significant differences were also found between individual operators for passenger ratings of how well their minke whale encounters were managed by the vessel crew. There was a large variation between vessels in the proportion of their passengers who indicated they were not adequately prepared for their minke whale interactions (ranging from 4.3% to 26%), as well as the proportion who indicated that they were not familiar with the Code of Practice (ranging from 2.7% to 78% for one vessel in 2008). Crew briefings and preparation of passengers emerged as the most important method of managing SWW participants. The Great Barrier Reef SWW activity represents one of the world’s few permitted and managed swim-with-cetaceans programs, and the collaboration between the Great Barrier Reef SWW industry, Reef managers and Minke Whale Project research team has been acknowledged by representatives from international wildlife conservation organisations (e.g. the Whale and Dolphin Conservation Society and the International Fund for Animal Welfare) as a world-leading example of adaptive management to achieve a sustainable whale watching industry. Many unresolved management issues however, remain (e.g. prevention of entanglements, risk management of highly interactive individual whales and cumulative longer-term impacts of interactions) and some key questions cannot yet be answered due to insufficient information about the wider Great Barrier Reef dwarf minke whale population (e.g. population characteristics, migration paths and external threats). The Minke Whale Project research team strongly advocate the continuation of long-term monitoring of the SWW activity and the initiation of new research to address these knowledge gaps. Without ongoing monitoring, stakeholder involvement and a commitment to adaptive management processes, as well efforts to improve our understanding of this special phenomenon, the sustainability of the Great Barrier Reef SWW activity cannot be guaranteed.