Tuesday, April 21, 2009

Airborne whale-cam hot on the minke trail

The Sydney Morning HeraldANDREW DARBY IN HOBARTAN INFRARED camera has shone light on one of the most divisive arguments of whale research - how many minkes are there in the Antarctic?The difficult task of counting whales has been eased by Australian scientists. In a global first they used the camera to find whales that have disappeared beneath the sea surface.Mounted on an aircraft flying over the polar pack ice zone, the infrared camera saw what the human eye could not - trails of warmer water left on the sea's surface between the ice floes."These are quite long trails left when a whale breaks the temperature meniscus at the surface," said Nick Gales, a biologist at the Australian Marine Mammal Centre in Hobart."In dead calm conditions, the animal brings up slightly warmer water from below. We know it's the whales doing this because we've been able to follow some animals that have re-emerged to take another breath."The breakthrough offers help in refining counts of whale abundance that now rely on statistical formulae to include unseen whales. It will be outlined today as part of the first meeting of the multi-national Southern Ocean Research Partnership in Sydney.Australian scientists made the discovery in the first aerial survey for minke whales in eastern Antarctica - waters where the animals are targeted by Japanese "research" whalers.The flights from Australia's Casey station led by Natalie Kelly of the CSIRO aboard CASA-212 ski-equipped aircraft covered nearly 3000 nautical miles of survey route last December.Estimates of Antarctic minke numbers are contentious. The International Whaling Commission's scientific committee has been unable to agree on them since 2000, when one calculation put them at half a 1991 estimate of 760,000.Dr Gales said hundreds of whales were seen in the pack ice survey - more killer whales than minkes. Data being analysed now would feed into new estimates to go before the commission in June."We're expecting in all likelihood to come up with lower [minke] numbers," he said.Ship-based surveys in the Southern Ocean over the past 20 years have found evidence of a decline in minke numbers.

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