Penguins gauge sea resources for scientists

STRUTTING and swimming through the Antarctic, some emperor penguins are working on a scientific mission: monitoring the sea resources of the polar region.

Every winter, emperor penguins -- the largest of the species -- travel long distances searching for food in open water, called polynias, that punctuate the sea ice. Penguins feed almost exclusively on squid, which is a vital food for many Antarctic Ocean creatures. Scientists say a knowledge of squid concentration in polynias can be obtained from penguin feeding patterns and this can be an indicator of the state of the sea's resources.

A French-American scientist team is using a satellite to monitor the seasonal movements of the penguins. The team, led by Yvon Le Maho of Centre Nationale de la Recherche Scientifique in Strasbourg and Gerald Kooyman of Scripps Institute of Oceanography, tracked the birds as many as 28 times a day to chart their course (Nature, Vol 360, No 6403).

Their tracking shows that in winter, penguins travel about 130 km to forage in polynias, covering the distance in about a fortnight at an average speed of 0.5 km per hour. In summer, penguins forage in open water along the edge of the pack ice and then return to nesting sites to feed their chicks, making round trips of upto 1,700 km. Penguins are estimated to gain weight while feeding in polynias at the rate of about 200 gm a day -- an indication of food availability in the sea. A transmitter attached to one of the birds showed penguins dive as much as 400 m in search of food.

The Maho-Kooyman team intends to compare the routes taken by the penguins with satellite images of the sea ice to obtain information on the resources of the polar region.