Over the last three decades, the International Whaling Commission has been undertaking boat based surveys outside of the pack ice in and around Antarctica to study the populations of minke whales. And over that time they’ve noticed an apparent decrease in the population numbers of minke whiles right around Antarctica. So one theory put forward to explain the apparent decrease of minke whales is that the boats can’t see the whales once they’re in the ice so essentially, they can’t count them, they’re not going to part of the abundance estimation. So the Australian government came up with an idea to use aircraft to survey minke whales in the pack ice along the coast of the Australian Antarctic Territory. So three years ago we started a pilot project to see whether we could use aircraft used in everyday Antarctic operations to look for and count whales and we found out thankfully that we can use the aircraft.
Our team was based at Casey station and at a field camp around four hundred kilometres to the west over the summer. From the survey perspective we would travel up to the plateau, pop in an aircraft, put our immersion suits on and fly out over the pack ice. And the survey process itself involves the observers squashed up against the tiny little aircraft windows for hours on end just staring out at the pack ice and counting every whale that we see. And we’re up there for many hours of the day. In the pack ice zone itself, we see minke whales and killer whales outside of the pack ice along the ice edge itself, other species congregate such as southern right whales and sperm whales. So in the first few that we undertook this project, we found that there were quite a few whales in the ice, in fact we counted around seventy-six minke whale individuals in the pack ice adjacent to Casey station.
In the following year, we extended the survey much further west across to the Shackleton ice shelf and we tripled the area that we were surveying and we expected to see three times as many whales, but we didn’t. This year we only saw about forty-three individuals, minke whales in the pack ice and that is a very interesting result. We believe that the decrease we observed in minke whale numbers from the 2008/9 summer to this summer probably has lots to do with where the pack ice is. This year the pack ice was incredibly dense so perhaps the whales aren’t coming in to the embayments because they have to go through many tens of nautical miles of solid pack ice to get to the open water for the south. That’s going to be a lot of hard work for the whales. It also suggests we need many more years of studying these populations in a single point and across a larger area, a broader range of longitudes, to truly understand how they’re moving and why they’re moving. I will be presenting the findings from our survey to the International Whaling Commission over the next few weeks. These are just preliminary findings at this stage. We’ve only been home for three months and over the next twelve to eighteen months we’ll be looking at minke whale distribution, just in the little area that we studied and trying to see whether we can match it with environmental data such as oceanographic information or sea ice data, all different sorts of environmental data to see whether there is a correlation there.
Environment Protection Minister Peter Garrett and Innovation Minister Senator Kim Carr today congratulated Australian researchers on the completion of the largest-ever aerial survey of whales off the Australian Antarctic coastline.
The team of five scientists aboard a fixed-wing aircraft surveyed 55,559 nautical miles of ocean and pack-ice off Australia’s Casey station for Antarctic minke whales over a two-month period from December 2009 to February 2010.
“This research is funded as part of the Government’s $32 million investment in non-lethal cetacean research. It is a landmark collaboration between the Australian Antarctic Division’s Australian Marine Mammal Centre and the CSIRO’s Wealth from Oceans Flagship”, Mr Garrett said.
“The study will help scientists better understand the importance of pack-ice habitat to whales, and how a changing climate may lead to substantial changes in the nature and declines in the extent of sea ice.
“This research shows yet again that there are effective ways to collect a whole range of important whale data without the need to kill these amazing creatures.”
Senator Carr said: “The team has developed novel statistical methods to analyse the data it collected, together with data from ship surveys. This gives us a much more accurate estimate of minke numbers in Antarctic waters.”
“This is a good illustration of how objective, rigorous science is critical for better ocean management.”
CSIRO statistician Dr Natalie Kelly said there were fewer whales spotted this year than in the first year of the survey in 2008–09.
“In the first year of the study we saw 76 minke whales, considerably more than the 47 we spotted this year,” Dr Kelly said.
“The decrease in the number of whales sighted, despite a threefold increase in the survey area, could have something to do with thick pack-ice conditions preventing the whales coming deeper into the ice,” Dr Kelly said.
“This variability also highlights the huge changes that can occur in population surveys in just one year, so it’s important that this work is carried on over a long period of time,” she said.
Dr Kelly will present her research findings at the International Whaling Commission’s Scientific Committee Meeting in Morocco next week.