Whales stranded during military test.

A puzzling episode of whale strandings along the western coast of Greece might have resulted from military tests of sonar going on at the time, speculates a Greek researcher.

On May 12 and 13, 1996, 12 Cuvier's beaked whales ran aground along the Kyparissiakos Gulf, where they eventually died. Two weeks later, another dead whale was discovered on the same stretch of coast.

Mass strandings of this species are "very very, very rare," says Alexandros Frantzis of the University of Athens. Searching through worldwide records going back to 1963, he found only seven incidents in which more than four of these whales ran aground at the same time.

His autopsies on the whales stranded in 1996 revealed "no apparent abnormalities or wounds," he reports in the March 5 Nature.

Frantzis points out, however, that the NATO research vessel Alliance was testing the experimental Low Frequency Active Sonar system in the region from May 11 to May 15. "Although pure coincidence cannot be excluded, it seems improbable that the two events were independent," he says.

Captain David Barron, spokesman for NATO's Allied Command Atlantic headquarters in Norfolk, Va., calls for more rigorous research on the proposed link. "The article does not establish any scientific cause and effect," he points out. The idea that low-frequency sonar bothered beaked whales sounds a little surprising to Robert Gisiner, who runs the marine mammal science program at the Office of Naval Research in Arlington, Va. Gisiner says he wouldn't expect beaked whales to respond to a low frequency because of the anatomy of their ears.