Scientists have for the first time recorded the extraordinary feeding behaviour of Antarctic minke whales, which are about 7 metres in length, showing the mammals lunge feeding up to 100 times per hour under the sea ice, gorging on krill.
The Americans and Australians attached multi-sensor suction cup satellite tags to minke whales off the west Antarctic Peninsula last year to study their foraging patterns.
Nick Gales, Chief Scientist of the Australian Antarctic Division, said the tags measured the whales’ orientation, depth and acceleration.
“Prior to this work the movements and diving behaviour of these whales was something of a mystery as no tags had been deployed on the species,” Dr Gales said.
“We found that the minkes were swimming just beneath the sea ice, feeding at incredibly high rates, taking mouthfuls of krill every 30 seconds.
“This is very different from other whale behaviour, for example the gigantic blue whales lunge up to four times during a dive and smaller humpbacks lunge up to 12 times.”
Dr Gales says the sensors are fixed to the whale’s back with suction cups which stay on the animal for up to 24 hours sending back data by the micro second.
“It illuminates every movement of the animal in the water which has enabled us to understand their feeding behaviour better,” he told Business Insider.
“It’s a real privilege working with the whales in a place like that,” he says. “It’s incredible and really fulfilling. It’s a wonderful office to have.
“It’s exhilarating for lots of reasons. You’re moving along fairly quickly and you don’t know when the whales are going to pop up next to you and if or when you are going to have an opportunity to put a tag on.
“With the suction cup tags they are worth about $25,000 each and they just fall off the whale when the suction breaks so you don’t know when the cup is going to come off. If they break off underneath the sea ice they will float up and lodge in the sea ice and we’ll never see it again.
“There’s quite a bit of tension as to whether we will get the tag back or not.”
Watch the tagging process here – the whale comes into full view at around the 1m10s mark.
The study also found the minkes’ size and manoeuvrability allows them to take advantage of the sea ice habitat.
“The minke’s preferred prey, Antarctic krill, aggregate under the sea ice and attract the whales to the area, leading to these feeding frenzies,” Dr Gales said.
“But any future change in sea ice has the potential to impact on the minke whales’ foraging habits.”
The study is part of the Australian-led Southern Ocean Research Partnership, which is focused on non-lethal research and is endorsed by the International Whaling Commission.
“It’s clear from the insight we have gained into the whales’ behaviour through this work, that you simply don’t have to kill the whales to study them,” said Dr Gales, who prepared Australia’s scientific case against Japan’s whaling activities in the Antarctic.
In an Australian led challenge, the International Court of Justice in April ruled that Japan’s so-called scientific whaling program was in contravention of the rules of the International Whaling Commission.
However, Japan has since raised the prospect of resuming catching Minke whales in the Antarctic.
The study was published in the Journal of Experimental Biology today.