First non-lethal whale study answers big questions
Between February and March this year, the six week Australia-New Zealand-led expedition used skin biopsy, photography, satellite tagging, and passive and active acoustics to study the population structure, distribution, movement, feeding and ecological role of Southern Ocean whales. The expedition was the first project conducted under the banner of the Southern Ocean Research Partnership (SORP), which was formed in March 2009 and involves 12 countries.
'The partnership aims to provide the results of non-lethal research to the International Whaling Commission as a scientific basis for sound conservation and management of Southern Ocean whales,' says expedition leader Dr Nick Gales, of the Australian Antarctic Division.
Photo: Anthony Hull
'This is the first time small boats have been used to work with whales on the high seas in the challenging Antarctic environment, but they proved highly successful, despite the generally poor weather experienced during the trip,' Dr Gales says.
Individual or pods of whales were sighted 326 times, accounting for at least 624 animals from eight species. Blue whales proved elusive, however, despite acoustic detection of their presence. Humpback whales were the most commonly sighted species, particularly around the Balleny Islands.
'On occasions when whales were sighted in good weather, the small boats were launched,' Dr Gales says.
'The sightings surveys will contribute to one of the major SORP projects investigating the distribution and mixing of Southern Hemisphere humpback whale populations around Antarctica.'
'The working tags will provide valuable data on the foraging behaviour of these animals, and we hope to be able to establish migratory routes between the Balleny Islands region and the tropical humpback whale breeding grounds,' Dr Gales says.
Photo-identification will also help build the distribution and mixing picture.
'Matching tail fluke photos taken in the feeding grounds on this expedition, with those taken on breeding grounds by others, will contribute to our understanding of the mixing between breeding populations on common feeding grounds in Antarctica,' Dr Gales says.
To complete the picture, genetic analysis of the skin biopsy samples from 64 humpback whales will give scientists an insight into, among other things, the population structure in Antarctic waters, and the sex composition of whales in Antarctica compared to those migrating along the East Australian coast. The team will also use genetic techniques to study age-related gene expression, which could lead to a simple, non-lethal ageing method for baleen whales.
'We did record a humpback whale song with the repetition of distinct stereotypic phrases,' Dr Gales says.
'As far as we know, this is the first instance where structured song-like sounds have been recorded from humpback whales on their Southern Ocean feeding grounds. Previously, it was thought that humpback whales only sang during their migration to and from, and while on their breeding grounds.'
The team also recorded a repetitive vocalisation in an aggregation of minke whales, revealing the likely source of a mystery sound.
'Repetitive song-like sounds have been recorded in long term Southern Ocean acoustic datasets, but the source of the "song" has never been identified,' Dr Gales says.
'The bearing to this sound from the sonobuoy was in the same direction that whales were sighted, supporting the likelihood that minke whales are the source of this "song"'.
Photo: Dave Allen
Dr Gales says the results of the Antarctic whale expedtion will be reported to the International Whaling Commission and shared with other members of the Southern Ocean Research Partnership.
Corporate Communications, Australian Antarctic Division