What's causing mass pelican and dolphin deaths in Peru?

Delays in the autopsies of thousands of dead pelicans and dolphins in Peru are causing difficulties for officials as they attempt to determine causes of death in these die-offs.

The carcasses of dead pelicans still litter the beaches of northern Peru, even as the last of nearly 900 dolphins are cleared away.

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The mass die-offs have Peruvian scientists searching for a cause and environmentalists raising questions about the government's ability to protect the Pacific nation's marine life, among the world's most abundant thanks to the Humboldt current that hugs most of its 1,500-mile (2,400-kilometer) coast.

After weeks of study, investigators say they think they know why at least 4,450 pelicans have died: Hotter than usual ocean temperatures have driven a type of anchovy deeper into the sea, beyond the reach of many young pelicans.

But Peruvian scientists studying the deaths of dolphins and porpoises from early February to mid-April say it remains a mystery, due in part to the government's slowness in investigating the phenomenon.

Authorities were so late in gathering tissues from the mammals that crucial clues were likely lost, said the scientist heading the dolphin death probe, Armando Hung, head of the molecular biology lab at Cayetano Heredia University.

At the same time, local officials have been so slow in removing carcasses that the Health Ministry urged the public last weekend to stay away from beaches from Lima, the coastal capital, northward, though it did not identify any specific health issue.

Up and down the coast, disoriented pelicans have been seen standing on beaches where they don't normally alight. Some have even been seen walking along coastal roadways.

Beginning at the end of January, daily catches of about 5 tons of anchovetas a day by fishermen in the northern region of Lambayeque dwindled after they began finding the small fish dead on the beach, said Fernando Nique, president of the Puerto Eten fishermen's association.

"After that, we haven't seen any more anchoveta," he said.

Patricia Majluf, a biologist and former deputy fisheries minister, said that tongues of warm water reach into coastal zones, driving anchovetas deeper underwater where many birds can't reach them.

"For a coast as dynamic as ours, it's not rare that this occurs," said Majluf. "It looks ugly because this has occurred at the same time and place (as the dolphin deaths)."

A biologist at the National University of Trujillo, Carlos Bocanegra, said his analysis of 10 dying pelicans last week supports that theory. Their digestive tracts were either empty or had the remains of fish pelicans don't normally eat.

Scientists say the dead pelicans are generally young, 3-4 years old, an age in which they do not dive as deep as their elders.

Ocean temperatures in the region, said Bocanegra, are currently 6 degrees Celsius (10 degrees Fahrenheit) above normal for this time of year, Peru's autumn.

A similar pelican die-off happened in 1982-1983 and again in 1997-1998 when the El Nino meteorological phenomena warmed the ocean, Bocanegra said.

"We saw mass deaths along Peru's entire coast, also associated with high sea temperatures. Pelicans, cormorants, Peruvian boobies and guanay cormorants died," he said.

The dolphin die-off, by contrast, remains a mystery.

Hung told The Associated Press that lab tests have so far ruled out a number of bacterial infections as the cause of the dolphin deaths, though other tests remain.

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