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It's a gorgeous day in western Bass Strait: the water is blue, the sun is shining and the wind is reasonably low. Alas, it's also our last day out on the water; we'll be heading back to port this evening to avoid strong winds and large swell that are predicted to move in tomorrow. Around dinner time last night we finally caught up with what was to become known as the 'Z Mission' (acousticians label groups of directional calls, i.e., putative groups of whales, by letters of the alphabet). The acousticians had been tracking (i.e., plotting its potential position on a map) a rather vocal blue whale for over 24 hours, and we ended up targeting (that is, physically moving over to where it is) this animal for around 21 hours. What was particularly perplexing about this singer was our inability to catch up, despite many hours of following. We were in deep water at this time (>1700 m), and the acousticians believe some there may have been some anomalies in the sound propagation, causing confusion about where the animal actually was. We persisted in our chase as these are conditions we expect to encounter in the Southern Ocean. Finally, after some judicious positioning of sonobuoys, some promising cross-bearings lead us to our quarry. Our reward after all that effort was some sensational photographs, particularly of high fluke-up dive. We're currently steaming parallel to the 150 m bathymetric contour, in a north-west direction, which is generally considered to be high-density blue whale habitat at this time of year. Despite a rather promising blow about an hour ago, which turned out to be a feeding fin whale, it's pretty quiet through here. Fingers crossed we encounter some more blue whales in the last hours of our survey. That would be a fitting end to what has been an incredibly productive and all round fun voyage. Friendships have been made and future research collaborations formed, all going to show that the value of these surveys are so much more than the data collected.
Regards: Natalie and Dave
Map
A map showing Australia and Antarctica. The map shows the journey of one voyage that has occured in the season, with each route highlighted in a distinct colour.