Albatross Cameras Solve Ocean Mystery

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Science

Monday, 12 October 2009 09:33

TINY 82g cameras attached to the backs of four albatrosses may have solved one of the mysteries of the vast southern ocean.

Scientists have long wondered how deepwater Patagonian toothfish come to be part of the diet of shallow-diving albatross.

It turns out the cheeky birds closely follow deep-diving killer whales to pick up scraps as they feast on toothfish.

Kentaro Sakamoto from Hokkaido University in Japan, Akinori Takahashi and Takashi Iwata from the Graduate University, Tokyo, and Philip Trathan from the British Antarctic Survey fitted cameras to four black-browed albatrosses.

The idea was to find out how albatrosses find food in such vast oceans.

The cameras, combined with depth data loggers, showed the birds dived only occasionally to about 4m and most often when other birds or killer whales were present.

The scientists think it at least partly explains how albatrosses find prey efficiently in an otherwise "featureless" ocean.

Their findings, mostly from an area off Bird Island, South Georgia, concur with ship-based observations of albatrosses following killer whales.

South Georgia is about 2000km east of Tierra del Fuego, at the tip of South America. It is one of the most remote places on earth.

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"When killer whales feed on fish, fragments of prey are often left near the sea surface," the scientists said in their paper published in the scientific journal Plos One.

"These prey fragments could be an important food resource for albatrosses."

Killer whales also are known to feed on toothfish by stripping them from longline fisheries.

Ironically, albatross and toothfish are both under threat from longliners.

A longline can be up to 100km in length, with branch lines each set with hundreds of thousands of hooks.

 

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