Hervey Bay a social hub for humpback whales
A new study has provided fresh evidence of the importance of Hervey Bay as a social hub for humpback whales.
The study is part of a long-term research program looking at the social behaviour and organisation of humpback whales, being undertaken by Trish and Wally Franklin, directors of The Oceania Project and PhD candidates with Southern Cross University’s Marine Ecology Research Centre.
Principal investigator Trish Franklin said the study revealed that there were significant changes in the composition of humpback whale pods during the migration season.
Results of the study will be published in the international journal Marine Mammal Science.
“The timing and grouping of different classes of humpback whales during the season means that Hervey Bay is a vital social habitat for eastern Australian humpback whales during the early stages of the southern migration,” Ms Franklin said.
“Humpback calves are rarely seen during the early part of the season from mid-July till late August. During this time large numbers of immature male and female humpback whales, accompanied by mature females without calves are travelling into, around and out of Hervey Bay.”
The next group to arrive are mature males and females during the latter half of August.
“It’s not until early September that the main flow of mothers with older calves commences and towards the end of the season, during October and November, mother-calf pods dominate the migration, along with male escorts,” Ms Franklin said.
An unexpected finding of the study was that mothers with calves in Hervey Bay spend the majority of their time alone with their calf involved in maternal care.
“When they do socialise, they are more likely to join with other pods which include a mother and calf,” she said.
“This differs greatly from other humpback whale areas, such as Hawaii, where mother-calf pods are usually accompanied by one of more male escorts and rarely are mother-calf pods reported mixing with other mothers and calves. In Hervey Bay, only one in 10 mother-calf pods attract one or more male escorts.”
Ms Franklin said over the 14 years of the study from 1992 to 2005 there was a significant increase in larger pods containing three or more humpback whales.
“This is likely to be related to changes in the behaviour of humpback whales as the numbers and density of whales in Hervey Bay increased from approximately 2000 humpback whales in 1992, to around 7000 in 2005,” she said.
Hervey Bay formed by Fraser Island, is a sheltered, shallow bay conveniently located just west of the main migratory pathway and is easily accessible to the humpback whales as they move south from their breeding grounds within the Great Barrier Reef.
“Geographically this is completely different to areas used by humpback whales in the northern hemisphere, such as Hawaii and the West Indies, where there is only open ocean between the breeding grounds and feeding areas,” said Wally Franklin.
“The combination of the variety of humpback whale social behaviour that occurs as different social groups visit the Bay, and its geography, is why Hervey Bay has become known as a unique whale watch destination.
“No matter what time of the season you visit the Bay to see humpback whales, you can expect to observe and experience something different.”
The Franklins conduct their research on the waters of Hervey Bay, heading out for a week at a time over the months of August, September and October.
This study was in part funded by The International Fund for Animal Welfare (IFAW), Southern Cross University and The Oceania Project through an Australian Research Council grant.
Mr Franklin said the principal funding for the study came from paying eco-volunteers, who join the research team aboard the expedition vessel for a week at a time and become involved in assisting with the research and learning about humpback whales.
For more information about the study see: www.oceania.org.au
If you are interested in participating in this years Expedition as an Eco-volunteer see: www.oceania.org.au/expedition/expedition.html
Photo: Hervey Bay is a social hub for migrating humpback whales.