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History and context
Dwarf minke whales are an undescribed subspecies of minke whale that occur throughout the southern hemisphere and were first recognised in the Great Barrier Reef in the 1980s1. As the name would imply, dwarf minke whales are smaller than other forms of minke whale (less than 8m), and are recognizable by their distinct colour patterns which include swirls and blazes not present in other minke whales and a distinct white shoulder patch2.
The Great Barrier Reef off the northeast coast of Australia has been a popular diving and snorkeling destination for many decades. It was declared a World Heritage Area in 1981, and in 2016 it attracted 2.4 million tourists3. In the 1990s, as divers and snorkellers began frequenting the outer shelf Ribbon Reefs north of Port Douglas on live-aboard dive vessels during the austral winter, they began to experience close encounters dwarf minke whales. From the mid-1990s onward dive tour operators began to advertise ‘swim-with-minke whales’ trips. Although swimming with whales in Australia was generally prohibited, a limited swim-with whale program was officially recognized, endorsed and permitted by the Great Barrier Reef Marine Park Authority in 2003. A cap was set on the number of operators (maximum of 9 permits) that would be able to offer swim-with-minke whales tours: all of which have been based in the Cairns and Port Douglas region.
Permits are issued under the condition that all vessels interacting with dwarf minke whales comply with a Code of Practice, and contribute to standardized monitoring of all their whale encounters. The operators are encouraged to share additional data from their encounters (underwater photos, etc) with researchers conducting long-term studies of the whale’s population biology and behaviour. More than 20 years of close collaboration between the dive operators, Reef managers, and scientists from the Minke Whale Project at James Cook University has resulted in an improved understanding of the whales’ population, behavior and migration, and has helped to refine management policy to ensure that the swim-with activities are managed sustainably.
An unusual aspect of the minke whale swims, is that the majority of encounters are initiated by the whales themselves, which often approach a stationary vessel or swimmers/divers who are already in the water4. Passenger-whale interactions tend to be extensive, lasting an average of more than two hours5. To ensure the safety of snorkelers during in-water encounters, and to prevent whales being chased or harassed, it is required for the operators to put out surface ropes for swimmers to hold onto.4
While little is known about the whales’ population and life history outside of their brief aggregation each winter in the Great Barrier Reef, photo-identification studies have allowed researchers to recognize individual whales that are re-sighted within and across seasons6,7. Analyses of data on the distribution, frequency, and duration of encounters have shown that whales are reliably found in a limited number of ‘hotspots’ in the Ribbon Reefs, and individual whales have been observed returning to these same places year after year. Such hotspots have been targeted with increasing frequency by permitted live-aboard vessels, resulting in highly reliable interactions each June-July season.