Southern Ocean food web - key for future fisheries

Macaroni penguins
Macaroni penguin colony (Photo: Eric Woehler)
Fur seal pup

17 February 2004

A landmark achievement in Antarctic marine research has provided a major step forward in understanding the food web of Heard Island and will provide key information to help ensure that fishing in the Southern Ocean region will not affect its ecology.

The first simultaneous land-sea research program on the ecology of the marine food web of Heard Island in the Southern Ocean has been hailed a success by scientists and support personnel, who have just returned from the area.

Led by Australian Antarctic Division (AAD) biologist, Dick Williams on board the Antarctic research ship, Aurora Australis. 24 scientists and support personnel have completed a major marine study on the foraging areas of three main predator species – king and macaroni penguins, and fur seals – around Heard Island.

The AAD program was carried out in tandem with 28 colleagues who were stationed on Heard Island. Together, the teams studied the interactions between the penguins and seals and their prey, the ocean environment potential impact on the assessment of commercial fisheries.

All core programs on the food web were completed along with large sections of supplementary programs studying the environmental factors that might influence the distribution and abundance of prey species in the region.

"The aim of the study is to determine the areas where king and macaroni penguins and Antarctic fur seals feed in the ocean around Heard Island and the characteristics of those areas that make them attractive to the predators," Mr Williams said.

"Some of the questions we looked at were whether the predators are feeding in a specific place because their preferred food is found only there, or whether they use only a relatively small part of the available foraging area because they feed regularly in a few locations close to the island.

"Our aim was to sample in areas where the three predators were feeding and to compare these results with nearby non-foraging areas," he said.

Mr Williams said that close cooperation with scientists based on Heard Island who were putting satellite trackers to the animals and monitoring their movements, dive patterns and diet made this work possible.

"We found that fur seals were targeting an area where they could find their preferred food, the mackerel icefish. King penguins tended to move over a very wide area but with some preferred locations whereas Macaroni penguins fed close to the island with their food type changing depending on how far from the island they could afford to go given their chick rearing duties.

"Extensive oceanographic data collected during the voyage also gave us some insight into why some areas are more productive than others," Mr Williams said.

This work is vital to understanding the interactions between the land-based predators and the marine area within Australia's 200 nautical mile Exclusive Economic Zone (EEZ) around Heard Island.

It provides essential data for developing ecological models of the area which can be used to assess conservation requirements and contribute to the management of established commercial fisheries.

Scientists involved in the land-based research on Heard Island will return to Australia in three weeks.