The dwindling march of the penguins is signaling that the world's oceans are in trouble, scientists now say.

Penguins may be the tuxedo-clad version of a canary in the coal mine, with generally ailing populations from a combination of global warming, ocean oil pollution, depleted fisheries, and tourism and development, according to a new scientific review paper.

A University of Washington biologist detailed specific problems around the world with remote penguin populations, linking their decline to the overall health of southern oceans.

"Now we're seeing effects (of human caused warming and pollution) in the most faraway places in the world," said conservation biologist P. Dee Boersma, author of the paper published in the July edition of the journal Bioscience."Many penguins we thought would be safe because they are not that close to people. And that's not true."

Scientists figure there are between 16 to 19 species of penguins. About a dozen are in some form of trouble, Boersma wrote. A few, such as the king penguin found in islands north of Antarctica, are improving in numbers, she said.

The International Union for the Conservation of Nature lists three penguin species as endangered, seven as vulnerable, which means they are "facing a high risk of extinction in the wild," and two more as "near threatened." About 15 years ago only five to seven penguin species were considered vulnerable, experts said.