Main summer Antarctic marine science voyage departs Hobart

3 January 2003

Dr Sharman Stone, Parliamentary Secretary for the Environment, has announced that a detailed study to estimate the small-scale distribution of Antarctic krill – a small, shrimp-like creature - in part of the Southern Ocean, will be carried out during an 11-week Antarctic research voyage on board Aurora Australis which leaves Hobart today.

Dr Stone said that the research would concentrate on the ocean north of Australia's Mawson station in eastern Antarctica, offshore from a long-running Adélie penguin monitoring program which supplies information to the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), the international body that manages the fisheries in the Antarctic region.

"We now know much about the life and times of krill. The Australian Antarctic Division, through its study of collected krill specimens in tanks at its laboratories south of Hobart, has contributed to the world's understanding of the biology of krill," said Dr Stone.

"However, we do not know the impact of krill harvesting on the survival of the species itself and on other species higher up the food chain. Many Antarctic species depend on krill for their food supply. For example whales, penguins, seals and sea birds rely on ready supplies of krill.

"We have seen huge krill harvests taken in years gone by. Krill have been swept up by the ship load for use as low-grade fertiliser and the like, despite our limited knowledge of the size of the total biomass," Dr Stone said.

"It's important that we understand more about the size and density of krill swarms and their relationship with the whole Southern Ocean ecosystem," said Dr Stone.

Voyage leader, Dr Steve Nicol, from the Australian Antarctic Division said that previous studies had proved inconclusive.

"Estimates of krill abundance from echo-sounders rarely agree with those we get using nets," said Dr Nicol.

"Catch limits for the krill fishery are set using information from echo-sounders and we need to have confidence in these numbers, so we have to examine the accuracy and precision of our sampling tools.

"Part of this exercise will also involve trials using sampling equipment in a small boat to examine the effect of the research vessel travelling over krill swarms to ascertain whether the ship's presence causes a change in krill behaviour or dispersal," Dr Nicol said.

"This is particularly important experimental work to help us understand the effect of large vessels on krill swarms and the subsequent effect on estimates of krill abundance,

"We'll also be trialling a stereo camera which we believe will give us a third way of estimating krill density," said Dr Nicol.

"The program, which is associated with the international GLOBEC (Global Ocean Ecosystem Dynamics) Program will determine krill distribution in the area where penguins are feeding and will examine whether swarms are moving past penguin colonies or staying put and what happens to them over time.

"We know that throughout the Antarctic the abundance of krill can vary markedly. When abundance is low there's a serious impact on the successful breeding ability of the birds," said Dr Nicol.

This marine biology research program will take place in tandem with an examination of the Antarctic Circumpolar Current, the world's largest current system that flows right around Antarctica joining and mixing the waters of the Pacific, Indian and Atlantic oceans. Its flow and variation will be studied in order to gain a better understanding of the interaction of ocean currents on climate.

Aurora Australis sails at 5 pm today.