Research Methods

Pete´s primary research focus has been aerial surveys which show the distribution of blue whales across a wide area over multiple seasons. We are now investigating and modeling blue whale habitat over a very large area between Bass Strait and the Great Australian Bight, by correlating aerial survey sightings data with habitat variables such as depth, and satellite-derived sea surface temperature and surface chlorophyll (ie phytoplankton). This research helps us to understand and describe areas of importance to blue whales, movement patterns of whales during upwelling seasons, and how varying upwelling intensity across seasons influences blue whale abundance.

Margie's current research examines blue whale habitat at a finer scale, using our small vessel Bonney Blue to conduct surveys in a focal area near the centre of the feeding ground. Our boat based studies are investigating the whales' prey (krill) and the whales´ foraging behaviour, using a specialised depth sounder to record the underwater presence of krill and fish, and suction-cup-attached dive loggers to record the underwater trajectory of the whales as they search for krill. While observers record the presence of whales, seals, seabirds and other marine phenomena, we also take oceanographic measurements to examine the upwelling structure and behaviour of the ocean.

At sea we routinely conduct photo-identification and biopsy. Photo-ID involves photographing the distinctive pigmentation patterns on the whales´ flanks, for comparison with databases held by ourselves and blue whale researchers elsewhere. It enables us to develop life history data for individual whales, including movements, calving intervals, associations between individuals, individual residence periods in certain areas, and so on. Biopsy involves the collection of a small amount of skin from free-swimming whales, for genetic analysis. It enables us to learn the sex of each individual, as well as the population group to which the whale belongs. In this way we are helping to understand the ´population structure´ of blue whales in the Southern Hemisphere, which has important conservation implications.

We have also been involved in migration studies using satellite tags attached to whales, to attempt to understand their movements between the Bonney Upwelling and other important feeding areas, as well as winter breeding areas. So far we have established a connection between the Bonney Upwelling and the Sub-tropical Convergence south of Australia, but the link to breeding areas remains elusive.

We have monitored upwelling dynamics by deploying temperature loggers, which record temperature at varying depths, for months at a time. We have also deployed passive acoustic loggers to record blue whale calls over periods of months. This helps to put local calls into a global context, to indicate impacts from human activities, and allow tracking of blue whale movements.

The multidisciplinary research that we are engaged in requires a range of skills and backgrounds. We therefore collaborate with a number of research groups.