Connectivity and Interchange Between Humpback Whale Aggregation Areas along East Australia

Project Name:

An Assessment of Connectivity and Interchange Between Humpback Whale Aggregation Areas along East Australia

Project Site(s):

Cairns/Cooktown Management Area of the Great Barrier Marine Park, Whitsunday Management Area of the Great Barrier Marine Park, Islands, Hervey Bay, Great Sandy Marine Park, QLD, and Eden, NSW.

Project Aims:

The study will undertake photo-identification surveys of humpback whales (Megaptera novaeangliae) at four locations along the east coast of Australia, with the aim of better defining the east Australian calving grounds, determining connectivity and rates of interchange between regions, and documenting habitat use within each aggregation area. Our findings will also be used to generate refined estimates of population status and reproductive parameters. This research will contribute to the conservation of humpback whales by providing managers with insight into population parameters, critical habitats and migratory pathways, thereby addressing high priorities of Federal/State management plans and the International Whaling Commission.

Project Justification:

Humpback whales are known to distribute widely over the Great Barrier Reef region. However, movement and use patterns are poorly understood, especially in areas north of 20˚S (Chaloupka and Osmond 1999, Forestell et al. 2003, Kaufman et al. 2010). Results from the proposed study will help define calving grounds and refine abundance estimates, which are essential for modelling population dynamics and developing effective management plans. By connecting data from the breeding grounds (Great Barrier Reef, Cooktown, Port Douglas, Whitsunday Islands and Hervey Bay) to a known gathering and feeding area at the southern end of the east Australian migration (Eden, NSW), the study will generate a better assessment of overall migratory pathways and rates of interchange between these regions. Furthermore, by broadening the survey effort into high latitude known breeding areas, we are likely to increase the rate of encounters with females and thereby increase the probability of tracking individual reproductive histories (Forestell et al. 2006).

The photo-identification holdings of Pacific Whale Foundation are recognized by the members of the International Whale Commission’s Scientific Committee as part of the ongoing Comprehensive Assessment of Southern Hemisphere Humpback Whales, an essential part of a collective database (including photographic, genetic, acoustic and observational data from other researchers) required to properly assess the status of Southern Hemisphere humpback whales. Due to the long-term nature of our data set, our existing and ongoing collection of photo-identification data will provide valuable background information for interpreting results from the proposed study.

Project Methodology:

Daily opportunistic surveys will be made from a 6.2 m rigid hull inflatable vessel equipped with a 150 hp outboard motor. Data collected will be in the form of digital photographs, GPS coordinates, sea surface temperatures, group size/composition, and behavioral observations recorded on pre-formatted data sheets. Audio recordings of songs and vocalizations will be collected using an Aquarian H2a-XLR hydrophone and a Edirol/Roland R-09R high-resolution digital audio recorder.

Digital fluke and lateral body photographs (when possible) will be collected for each identified whale using established procedures and Canon 7D digital cameras equipped with 100-400mm lenses (Forestell et al. 2003). Identification photographs will be compared to Pacific Whale Foundation's Southern Hemisphere Humpback Whale Catalogue that contains fluke photo-identification records of nearly 6,000 individuals. To select individual identifications suitable for re-sight analysis, all images will be scored according to the Cascadia Research Collective’s fluke image screening criteria (Calambokidis et al. 2008).

Aerial surveys in the Port Douglas/Cairns region were flown once per week using a fixed-wing aircraft along pre-determined transect lines in 1992 and 2004 (Forestell et al. 1993).

Management Outcomes:

The outcomes of this research will help define calving grounds, return rates, calving intervals and individual reproductive success rates. The proposed project will address IWC “Scientific Committee Recommendations Relevant to Southern Ocean Research” (SC/SORP 4) by filling in gaps of known or suspected regions of past or present high whale density in particular the Great Barrier Reef East Australian migratory corridor, and continues surveys in regards to evaluating trends in abundance for east Australia (Cooktown, Port Douglas, Whitsundays, Hervey Bay and Eden). This project also addresses objectives of the “Humpback Whale Recovery Plan 2005 – 2010" by monitoring population status and assessing habitat use, and by refining and defining knowledge of calving, resting and migratory areas, particularly in areas where human activity is high (e.g. Whitsundays & Port Douglas). Findings from this study will be incorporated into the IWC Comprehensive Assessment of South Hemisphere humpback whales, Breeding Stocks D, E and F.