Peru dolphin deaths unsolved
Lima - The mass die-off of nearly 900 dolphins and porpoises along Peru's coast remains unsolved, Peru's government marine research agency says.
Tuesday's final report by the Sea Institute ruled out viral and bacterial infections, human intervention, pesticides or heavy metals as causes for the deaths, which were first noticed on 7 February and continued through mid-April. It speculated that biotoxins, algae blooms, or an unknown emerging disease could be to blame.
The Peruvian environmental group Orca, which first alerted the public to the deaths, insists that seismic testing used in oil exploration was likely the cause.
But the Institute said that experts found no evidence any of the deaths were a result of seismic soundings, which involve shooting compressed air at the sea floor: There were no signs of internal haemorrhages or brain lesions that would be compatible with damage from such tests. But it said it did notice damage to some plankton where the soundings were done.
Orca contested those findings in its own report on Tuesday, saying it had independently confirmed haemorrhages and middle-ear infections as well as the presence of air bubbles in internal organs and severe lung damage.
Several leading Peruvian scientists complained that the government agency was late in gathering samples, making it harder to determine the cause of death because the tissue tested was so badly decomposed.
The Sea institute based its findings on autopsies of just two dead dolphins, which were collected in mid-April, while Orca said it gathered the first of the samples it tested on 12 February.
Seismic testing in the area was conducted between 7 February and 8 April by Houston-based BPZ Energy.
The Institute report said the testing occurred 80km to 130km off shore and that the equipment used was calibrated in those waters between 31 January and 7 February.
It said testing also ruled out morbillivirus, a type of distemper that some government officials had suggested as a likely cause long before kits arrived from the US to check for it.