Continued from page 1

“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.

Because the dolphins were so decomposed, Hung said, it was impossible to rule out a theory promoted by the sea mammal conservation group Orca, which initially publicized the dolphin die-off. Its director, Carlos Yaipen, says he believes the cetaceans were killed by shock waves generated by acoustic “explosions” used to test the sea bed for oil deposits.

Yaipen told a congressional hearing Tuesday the ORCA did 30 autopsies of dolphins found along a 80-mile (130-kilometer) stretch of coastline, receiving the first batch on Feb. 12, and found broken bones in their ears, internal hemorrhages and collapsed livers.

“In microscopic exams we found fatty tissue with a great quantity of surrounding bubbles and hemorrhages. This happens when there is a strong sound in the fatty tissue, in the mandibular fat where sounds are received,” he said.

The government agency in charge of the investigation, the Peruvian Sea Institute, or IMARPE, did not provide an explanation for the delay in obtaining dolphin samples for testing.

“At the moment I have no answer,” agency spokesman Vicente Palomino said Tuesday.

Government officials have said they have no evidence the dolphin deaths are related to seismic oil exploration work that was carried out off northern Peru between Feb. 8 and April 8 by the Houston-based company BPZ Energy, and the company says it doesn’t believe the deaths were related.

Hundreds of dolphins have at times turned up dead on beaches in various parts of the world, though the number in northern Peru was particularly high.

Scientists have said that agrochemical runoff from rivers or heavy metals from upstream mining could be potential factors in the Peru dolphin deaths.

However, IMARPE’s director, Raul Castillo, said Tuesday that the two autopsies done for it had ruled out heavy metals “like lead, cadmium and copper” as well as pesticides and three marine biotoxins. There are more biotoxins, he said, but no local labs to test for them.

Castillo said two viruses, brucella and leptospira, were also ruled out and a test was still pending for morbillivirus, which is similar to distemper. The kit needed for that test had to be ordered from the United States and was clearing Peruvian customs.

Sue Rocca, a U.S.-based marine biologist with the Whale and Dolphin Conservation Society, said blooms of algae and other biotoxins are known to affect marine mammals and could be involved.

“One of the things we do know is just how fragile we have discovered our ecosystems have become,” she said.

Story Continues →