Birtles et al., 2008:

"Over the five year period 2003-2007, 91 per cent (1042/1149) of reported Great Barrier Reef dwarf minke whale encounters occurred during June and July. In 2007, 89 per cent (241/272) of minke whale encounters were during these months. This temporal distribution of minke whale sightings is consistent with previous years (88 per cent in 2006, 95 per cent in 2005, 93 per cent in 2004 and 89 per cent in 2003).

A total of 784 minke whales were reported to be observed in 2007 (compared with 826 whales in 2006, 674 in 2005, 540 in 2004 and 562 in 2003).

The total encounter time in 2007 (412hrs; n=272) is higher than in previous years (2006 was 387.3hrs, 2005 was 297.5hrs, 2004 was 285.7hrs, 2003 was 237.4hrs), reflecting a trend of increasing total interaction time over the five-year period.  It is likely that this trend is an indication of increasing industry ‘effort’ or use of dive sites where minkes are more likely to be encountered (particularly in the Ribbon 9/10 area) rather than a change in minke whale abundance or behaviour, however this remains to be quantified.

Status of vessel data provide an important indicator of the voluntary nature of approaches to the vessels by whales.  The status of vessel at the time of first sighting was recorded on 271/272 (99.6 per cent) of the Whale Sighting Sheets (WSS)  2007 relating to Great Barrier Reef dwarf minke whale encounters. The amount of dedicated searching in open water varies between vessels, but for the industry overall, the majority of encounters in 2007 (80.5 per cent) were initiated with vessels not underway (either anchored or moored).  This result is consistent with previous years.

In-water interactions involving snorkellers and/or scuba divers occurred in 173/272 (64 per cent) encounters in 2007 (compared with 63 per cent in 2006, 72 per cent in 2005, 76 per cent in 2004 and 61 per cent in 2003).  This overall figure does not necessarily indicate changes in the interactivity of the whales between years, and may be due to variable reporting of sightings of distant whales by different vessels.

These results however are consistent with WSS collected from Undersea Explorer (58 per cent in 2007, 63 per cent in 2006, 70 per cent in 2005, 70 per cent in 2004, 58 per cent in 2003), where researchers conduct a full daylight-hours watch and all sightings (near or distant) are logged. This variable is likely to be an important indicator of potential changes in the ‘interactivity’ of dwarf minke whales, but must be standardised for any changes in industry patterns of resource use (i.e. effort).

Close and very close approaches are indicative of a high level of interactivity of the whales. Very close approaches to swimmers, ropes and/or the vessel however may pose a risk to the whales themselves or swimming participants, especially if these approaches are in combination with behaviours such as “headrise/spyhop”, “motorboating” and “breaching”.

Preliminary results from the PhD study by A. Mangott suggest that such occurrences are relatively rare and are most likely to be from only a few individual whales."

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Citation and/or URL

Birtles, A., Curnock, M., Mangott, A., Sobtzick, S. and Valentine, P. 2008, Dwarf Minke Whale Tourism Monitoring Programme: 2007 Season Draft Final Report to the Great Barrier Reef Marine Park Authority, 14 June 2008  

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Spatial Coverage

Offshore Port Douglas and Ribbon Reef Sectors of the Great Barrier Reef Marine Park 

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Temporal Coverage

2003-2007 

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Update Frequency

Not applicable 

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Other Information

None