Posted on: September 9, 2012

PWF Research Results From 21 Years in Hervey Bay Published in Scientific Journal

A Pacific Whale Foundation research study in Hervey Bay from 1987 to 2007 provided the basis for a scientific research paper titled “Long-Term Trends in Abundance of Humpback Whales in Hervey Bay, Australia,”  published recently in Journal of Cetacean Research and Management (Special Issue 3).

Pacific Whale Foundation is a non-government organisation that has studied humpback whales in Australia since 1984, as well as Hawaii and other parts of the Pacific since 1980. 
 
The paper's authors are Gregory D. Kaufman, Pacific Whale Foundation's founder and Executive Director; Paul H. Forestell, who served as Pacific Whale Foundation Research Director and is now the Provost of C.W. Post Campus of Long Island University in Brookville, New York; and Milani Chaloupka, of Ecological Modeling Services Pty Ltd, University of Queensland, in St. Lucia, Queensland. 
 
The paper focused on 3,155 individual humpback whales that Pacific Whale Foundation had photo-identified in Hervey Bay during the 21 year period between 1987 and 2007. 
 
According to the publication, Hervey Bay is a major southbound stop-over site for a population of humpback whales (known as "Breeding Stock E") that over-winter in the vicinity of the Great Barrier Reef and then migrate along Australia's eastern coast to return to their feeding areas in Antarctica.  
 
Pacific Whale Foundation's researchers had individually identified 3,155 humpback whales in Hervey Bay between 1987 and 2007 using a non-lethal technique known as photo-identification. 
 
The researchers worked from small boats in Hervey Bay, observing whales and collecting fluke identification photos of individual whales.  To do so, the researchers photographed the ventral, or underside, of each whale's flukes -- a body area that's usually visible when  a whale prepares to dive and lifts its tail above the water to gain momentum. 
 
By closely examining the fluke photographs, researchers can individually identify whales based on the unique visual appearance of each animal's flukes. Factors such as the shape and outline of the flukes, as well as pigmentation, visible scars and other markings, differentiate one whale from another. The researchers compare the identification photos from each year against those from prior years, to flag “resights” – those animals sighted in Hervey Bay during multiple years.
 
Based on scientific modeling techniques, the publication’s authors established annual estimates of the number of humpback whales in Hervey Bay, which showed an average estimated rate of increase of 13.4% per year. The scientists also estimated that the number of humpback whales stopping over in Hervey Bay in 2007 included approximately 6,246 yearling whales. 
 
Calves were not included in the study because they rarely expose the ventral surface of their flukes and because there can be significant change in pigmentation patterning on their flukes during their first year of life. 
 
"This long-term study of the humpback whales of Hervey Bay helps to reinforce prior assertions that the population of Breeding Stock E humpback whales is making a comeback, after being severely depleted by commercial whaling in the 1950s and early 1960s," says Greg Kaufman. "Our results support the findings of other studies of this population, including  shore-based observations in Southern Queensland waters, aerial surveys of the Great Barrier Reef Marine Park and analysis of photo-identification data."
 
"There is one area where our data doesn't match other studies," says Kaufman. "The estimated rate of increase outlined in the Pacific Whale Foundation report is significantly higher than the rate of  increase estimated recently for several recovering Southern Hemisphere humpback whale stocks based on studies of whales in their feeding grounds near Antarctica."
 
"In other words, what we're seeing along the coast of east Australia isn't matching with what they are finding in the whales' feeding areas near Australia," he notes. "It's a mystery to be resolved." 
 
The recently published Pacific Whale Foundation study also examined the amount of time between sightings of individual whales. The researchers grouped the whales into two categories: “transients” (whales seen only once by the researchers) and “non-triansients” (whales seen during two or more years). “We are unsure about the reason for these ‘transients,’ says Kaufman. “Perhaps they are younger and inexperienced and thus have a lower survival rate, or perhaps they migrate to other areas.”
 
“Either theory runs counter to current scientific belief about the fidelity that Breeding Stock E whales demonstrate to their migratory routes along the East Australia coast,” he notes. “Understanding and measuring possible transient behaviour, especially if it reflects shifts in the whales’ breeding stocks or breeding areas, is important for future assessments of changes in the population of humpback whales in this region.
 
Queensland Department of the Environment, Parks and Wildlife Service and Matilda Cruises helped to fund Pacific Whale Foundation’s study and publication. All work was conducted under permit from the Queensland government. 
 
Although the study period spanned 1987 through 2007, Pacific Whale Foundation has continued to study humpback whales in Hervey Bay each year since then. Pacific Whale Foundation's research continues in Hervey Bay this year, with staff researchers stationed aboard Pacific Whale Foundation's commercial whalewatch tours in Hervey Bay to gather data on whales sighted during the cruises.  
 
"One question from this year's International Whaling Commission meeting was whether whalewatch vessels could serve as 'Platforms of Opportunity' from which researchers could gather viable data about whales," says Kaufman. "By stationing researchers on our vessel, Explorer, we are working to answer that question right now." 
 
"So far it's been a great season, with many whale sightings and many fluke identification photos gathered by our research team," he notes. 
 
Pacific Whale Foundation is offering educational whalewatches in Hervey Bay, to help raise funds for its ongoing research in Australia. To learn more about Pacific Whale Foundation’s work in Australia and whalewatching with Pacific Whale Foundation, please visit www.pacificwhale.com/au or www.pacificwhale.org.
 
 
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ABSTRACT: 
Long term trends in abundance of humpback whales in Hervey Bay, Australia

PAUL H. FORESTELL*, +, GREGORY D. KAUFMAN* AND MILANI CHALOUPKA

Contact e-mail: paul.forestell@liu.edu

ABSTRACT
Seasonal abundance estimates of humpback whales resident during the austral winter in Hervey Bay, Queensland, Australia between 1987 and 2007 were obtained from a capture-mark-recapture study using photo-identification images of 3,155 individual whales. Hervey Bay is a major southbound stopover site for Breeding Stock E humpback whales returning to Antarctic waters from over-wintering in the vicinity of the Great Barrier Reef.
 
Annual survival, recapture and abundance estimates were derived using a Cormack-Jolly-Seber modelling approach and a Horwitz-Thompson type abundance estimator. The best-fit model was a 2-ageclass Brownie-Robson type model that estimated apparent annual survival for the non-transient winter stopover ageclass at approximately 0.945 (95% confidence interval: 0.929–0.957). Apparent annual abundance of winter stopover humpback whales in Hervey Bay was estimated to have increased significantly over the past 21 years at ca. 13.4% per annum (95% CI 11.6–15.2). The most recent Hervey Bay winter stopover population (2007) was estimated to comprise ca. 6,246 post-yearlings (95% CI 5,011–7,482). This estimated rate of population increase is similar to estimates for other surveys along the east Australian coast but significantly higher than the intrinsic rate of increase (rmax) estimated recently for several recovering Southern Hemisphere humpback whale stocks based on the feeding ground sampling.
 
KEYWORDS: HUMPBACK WHALE; ABUNDANCE ESTIMATE; MARK-RECAPTURE; PHOTO-ID; AUSTRALIA; SOUTHERN HEMISPHERE; STATISTICS