Population characteristics and migratory movements of humpback whales (Megaptera novaeangliae) identified on their southern migration past Ballina, eastern Australia
The annual migration of humpback whales (Megaptera novaeangliae) from their summer feeding grounds in polar waters to their winter breeding and calving areas in lower latitudes constitutes one of the longest movements of any mammal. Land-based and vessel-based surveys were conducted from 2003-2005 o...
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | unknown |
| Published: |
ePublications@SCU
2010
|
| Subjects: | |
| Online Access: | https://epubs.scu.edu.au/theses/273 https://epubs.scu.edu.au/cgi/viewcontent.cgi?article=1270&context=theses |
| Summary: | The annual migration of humpback whales (Megaptera novaeangliae) from their summer feeding grounds in polar waters to their winter breeding and calving areas in lower latitudes constitutes one of the longest movements of any mammal. Land-based and vessel-based surveys were conducted from 2003-2005 off the coast of Ballina in northern NSW, Australia, to determine population characteristics and movement patterns of humpback whales on their southern migration from the putative breeding grounds in Queensland waters to the Antarctic feeding grounds. A total of 1237 pods comprised of 2151 humpback whales were recorded from the land station, and 448 pods comprised of 1081 humpback whales were recorded from the research vessel, including 609 individuals that were identified from fluke photographs. Of these, thirteen whales (2.1%) were seen on more than one day within a season at Ballina, with related data suggesting that some males may circle back northward during their southern migration, possibly in search of mating opportunities. Twenty individuals were identified in more than one year of the surveys, and resighting data revealed a high level of consistency in the timing of migration of most resighted individuals from year to year. Land-based surveys showed that pods with a calf tended to migrate past Ballina in shallower, inshore waters, and also swam more slowly, with more changes in direction on average, than pods without a calf. The overall group characteristics and behaviour of whales observed in this study most closely resembled those of whales on breeding grounds elsewhere, suggesting that breeding behaviour continues during the southern migration off eastern Australia. Collaborative matching of fluke photographs from this project with two other research projects that focused on humpback whales migrating north past Byron Bay and in Hervey Bay respectively, revealed a total of 80 individual withinseason movements of humpback whales between the three study sites. These collaborative records were also used in capture-recapture analyses to estimate the abundance of the Group E(i) population that migrated along the eastern coast of Australia in 2005, resulting in an estimate of 7024 (5163 - 9685 95% C.I.) whales. Collaborative matching of fluke photographs from this project with catalogues from New Zealand, the Balleny Islands, New Caledonia and Tonga revealed a small number of whales from Ballina that were resighted in these locations. Advances in photo-identification methods were also investigated during this study, resulting in the collaborative development and testing of a successful new computerised fluke-matching system, Fluke Matcher. This fluke-matching program will greatly increase the efficiency of reconciling humpback whale photoidentification data in the future. |
|---|