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WILDLIFE researchers have come up with a simple way to figure out who鈥檚
eating who. They say a sea lion鈥檚 blubber should reveal what fish it has been
munching on, which could help solve a debate over Alaska鈥檚 fishing policy. But
other scientists insist the technique will never work.

The US government and courts have been trying to stop fishermen trawling for
pollack near Steller sea lion rookeries to make sure the endangered animals have
enough food. But some researchers say the sea lions don鈥檛 eat pollack, they
prefer herring
(New Scientist, 30 June, p 18).

To gauge what the predators have been eating, scientists usually have to
search through their faeces鈥攁n unpleasant and notoriously unreliable
procedure. But the answer could lie in the make-up of the animal鈥檚 fat, says
Sara Iverson of Dalhousie University in Nova Scotia.

Iverson plans to use a biopsy dart to sample and analyse the fatty acids in
the blubber of the sea lions, and then compare them with fatty acids in
potential prey. If the two match, it will give a reliable guide to the quantity
and type of prey the sea lions have been feeding on. 鈥淵ou can get information
about free-ranging animals that you could never get before,鈥� she told the marine
mammal meeting in Vancouver.

But chemist Otto Grahl-Nielsen of the University of Bergen in Norway argues
that up to 90 per cent of fatty acids are metabolised before they can be laid
down in fat. The rest undergo so many changes that it would be futile to compare
them with the ratios in prey. 鈥淚f it worked, it would be very nice,鈥� says
Grahl-Nielsen. 鈥淏ut it doesn鈥檛.鈥�