Abundance of the east Australian humpback whale population
Prior to the 1950s, there was little exploitation of the east Australian humpback whale population. In 1952 industrial shore-based whaling commenced at Tangalooma on Moreton Island and a year later at Byron Bay. Together with massive illegal pelagic whaling in the Southern Ocean in the early 1960s, whales were taken in such numbers that the population collapsed by 1962. The original estimate of humpbacks across most of the western South Pacific region (breeding group E) during the early 1960s was approximately 10,000 whales but this has been upwardly revised in light of the recently reported catches in the Southern Ocean. It is now thought that there were between 35,000 – 40,000 humpbacks with a majority of these belonging to the east Australian population. Estimates vary as to how many remained by the mid-1960s, but it is likely there were only a few hundred whales left.
Post-whaling surveys of the east Australian population were initiated at Point Lookout, North Stradbroke Island, in 1978, and have continued every one to three years since then. At the latitude of Point Lookout (27° 30' S) in southeast Queensland, the northward migration peaks between mid-June and mid-July. Between the late 1970s and early 2000s, two independent teams conducted surveys from this location. The first series was initiated by Michael Bryden, originally from the University of Queensland, then from the University of Sydney, and continued by his PhD student, Miranda Brown, until 2000. The other series of surveys, from the early 1980s to 2002, were conducted by Robert Paterson, a Brisbane radiologist, his wife Patricia, and Doug Cato. We took over the surveys in 2004, conducting a survey in that year and again in 2007 and 2010, allowing us the opportunity to build on these two excellent series of surveys. The 2004 survey was a 14 week survey with double-platform land-based counts to produce an absolute abundance estimate. The 2007 survey and 2010 surveys were, by contrast, shorter (6 and 8 weeks, respectively) designed to estimate relative abundance. The 2007 survey included aerial as well as land-based counts. During the 2010 survey, we moved the primary survey site at Point Lookout, which also involved land-based double counts to calibrate the new site.
The population has rebounded from whaling strongly. Over the last 27 years there has been a very consistent rate of increase of between 10 and 11% per annum – effectively a doubling of the population every seven years or so. In 2010, we estimated that the population was around 15,000 whales. The next survey will probably be another long 14 week survey in 2013. (Project leaders: Mike Noad, Rebecca Dunlop)