Antarctic minke whales (Balaenoptera bonaerensis) are one of the smallest species of baleen whales (which include blue and humpback whales) and the only baleen species that is still common in the seas around Antarctica. Although they are the most abundant of the great whale species, research presented to the International Whaling Commission indicates an apparent decrease in their number over the last few decades. But whether this decrease is real, or merely the result of the survey method, remains a point of contention.
The data detailing Antarctic minke whale numbers and locations were collected over the last 20 years from non ice-strengthened ships, which necessarily had to skirt the ice edge for safety. Even during summer, fragmented pack ice can extend many hundreds of kilometres out to sea, representing a vast area that these ships cannot access. One theory for the apparent decrease in Antarctic minke whales is that the animals have moved further into these ice zones, away from the view of research ships. This theory led to the idea that perhaps whales in pack ice could be counted from the air.
To develop this concept the Australian Antarctic Division, in collaboration with CSIRO, started an aerial survey program to study minke whales in various pack ice habitats in eastern Antarctica. The platform selected for the survey was a C212-400, a twin turboprop military transport aircraft, which can accommodate an observing team of four people and a flight leader (known informally as ‘Team Minke'). High-definition video cameras, a high-resolution digital stills camera and an infrared camera were installed in the base of the aircraft, to detect whales underneath the aircraft, hidden from the view of the observers, and to collect data on pack ice habitat (Australian Antarctic Magazine 13: 8, 2007).
Like any activity involving aircraft, much preparation is needed for safe flying in Antarctica. The aerial survey team members have to be trained for underwater aircraft escape and field survival. They must also wear an immersion suit when flying, which aids survival in cold water (albeit the discomfort after wearing it for a few hours). Survey flights must also be planned around weather systems, which can ground aircraft for many weeks at a stretch. Negotiating the combination of aircraft and Antarctica is a challenge indeed!
The aerial survey programme has now been running for two summer seasons.
The first survey in 2007-08, tested the concept of flying aerial surveys using C212 aircraft from an Australian Antarctic station. In 2008-09 a 'full' survey was flown over Vincennes Bay near Casey station (66º 17'; S 110º 32'; E). This full survey was considered a great success, with nearly 500 whales counted in transects covering some 3000 nautical miles, during 40 hours of flying. In total, 76 Antarctic minke whales, 372 killer whales and 27 of unknown whale species were observed. Many whales were also detected with the various cameras, in some cases confirming ambiguous observer sightings – enough to build confidence in the future of such technologies to assist in marine mammal research.
The full survey is thought to represent the first ever fixed-wing aerial survey for whales in Antarctica (a team of German scientists have recently been surveying for minke whales using helicopters from a ship). Preliminary results from the survey will be presented to the International Whaling Commission meeting in Madeira in June 2009. Longer term, it is hoped that results from the aerial survey program in eastern Antarctica will be considered alongside those from the German helicopter surveys, to provide a better understanding of where Antarctic minke whales are congregating during the summer months and if, in fact, this can explain the decline in their numbers.
Planning is also underway for an extended aerial survey during the 2009–10 summer season, which will extend west from Casey station over to the Davis Sea.
Australian Marine Mammal Centre, CSIRO