Yesterday Melbourne was set abuzz with the news of some rather exciting guests in Port Phillip Bay. A pod of Killer Whales (also known as orcas) was spotted travelling up the bay as far as Mornington & Mount Martha with several lucky Melbournians catching sight of the pod as it traveled by. Although their visit sparked a flurry of surprise and excitement from locals, orcas are not as uncommon to our waters as many might think.
Wild Melbourne spoke briefly with David Donnelly of the Australian Orca Database to find out more about these mysterious visitors. Dave tells us that while it is somewhat of a rarity for orcas to venture as far north in the bay as witnessed yesterday, orcas have been recorded on several occasions in the southern areas of the bay and areas just outside of Port Phillip Heads. Data compiled from the Australian Orca Database over the years suggests that orcas are not uncommon to areas such as Queenscliff, Phillip Island, and Wilsons Promontory. The latter two sites seem to be particularly popular, as they host large seal colonies for orcas to predate on.
Interestingly, the collected data suggests that around the Port Phillip area, May to June and December to February are the peak periods for orca sightings. The reasons for these trends are largely unclear, although the movement between May to June seems to be at least in part due to prey activity, as the timing loosely correlates with the humpback whale migration and when young and naïve seal pups become independent from their mothers, thus making them easy prey. The December to February spike is again unclear, though many of the individuals sighted in Victorian waters at this time have been found to travel on to Tasmania or the Bonney Upwelling off Portland.
Finding the answers to these questions will not be easy. Orcas are renowned among marine biologists for being notoriously difficult to research. However, it is undeniable that understanding the migratory patterns of the world’s largest dolphins is an extremely exciting venture both here and abroad. What makes it even more exciting is that you and I can help with this research!
The difficult nature of orca research means that much of the data compiled by the Australian Orca Database comes from reported sightings and photos taken by everyday citizens that were lucky enough to encounter orcas by chance, much like those lucky few at Mount Martha yesterday. We strongly encourage you to send any photos or information you have from recent or future encounters with orcas to the Australian Orca Database using the links below.
Of course, while we understand that an encounter with a pod of orcas can be an overwhelming experience, it is vital for the safety of these animals and the public that we follow the regulations set by the Department of Environment, Land, Water and Planning of a minimum approach distance of 200 metres for boats and 300 metres for jetskis. For the most part, yesterday’s encounter was one of respect; unfortunately, however, there were a few boats seen harassing the pod.
Yesterday was another example of Melbourne’s marine marvels that exist right on our doorstep. Although finding orcas can be a tad tricky, with the water warming up for summer it is a great time to get out and explore the various underwater wonders of the bay that we’re lucky enough to call home.
Evatt is an evolutionary ecologist whose research focuses on how natural populations can adapt to environmental change. He is currently undertaking his PhD at Monash University.
You can find him on Twitter @EvattChirgwin