Invercargill, Jan 30 - The Department of Conservation (DOC) is treating the mass sea lion deaths in the Auckland Islands as a biohazard.
DOC staff found about 1000 dead pups on the main sea lion rookeries this week.
They say they are getting as much advice as they can about what the risks are to staff working with the sea lions.
Staff on Dundas Island, where the main bulk of sea lions have died, have performed autopsies on some of the animals.
DOC biodiversity technical support manager Andy Roberts said staff were concerned about the health risks they faced dealing with the sea lion carcasses.
One of the possible causes of the deaths could be morbillivirus, also known as seal distemper.
There have been outbreaks of morbillivirus in seals about four times in the past 10 years, decimating seal populations in Ireland, Spain and more recently the United States.
Although there appears to be no recorded incidences of the seal morbillivirus affecting humans, two Australians died after contracting equine morbillivirus from a horse.
Mr Roberts said DOC staff were keeping an open mind about just what was responsible for the deaths and had not discounted an algae bloom, bacterial infection or other viral infections.
DOC was ensuring staff used all available precautions when dealing with the infected sea lions.
``We don't know how far it has spread, naturally, and it may be in other populations around here. We don't actually know what we are dealing with.''
Staff on site at the infected colony were keen to get some information about what health dangers they were facing themselves, he said.
DOC had advised the Ministry of Agriculture biosecurity unit and the Ministry of Fisheries about the incident.
DOC MARINE MAMMAL expert Mike Donoghue said the samples and sea lion carcasses brought back to the mainland had been quarantined.
However, he was confident staff on the Auckland Islands, which included a veterinarian, were taking the necessary precautions.
The public is also being urged not to touch any dead seal carcasses.
Although the first sea lion tissue, gut and full body samples have reached Massey University experts, it was understood it would be at least 48 hours before they had thawed sufficiently for testing, and much longer before results could be known.
Massey University CETACEAN investigation unit head Per Madie said some similar disasters had in the past been linked to distemper-related viruses.
In 1988 an epidemic among grey seals in Europe had killed 17,000.
But this and many other viruses were not known ``to jump the species barrier''.
``They're quite host specific,'' he said.
Dr Madie said that since 1988 there had been similar large scale deaths of monk seals in the western Mediterranean, and along the Mauritanean coast, as well as mass deaths of fur seals off Namibia.
``There does not have to be a link but one could imagine how it crosses vast distances because of the feeding habits of seals.
``It's purely speculative, but the most likely cause would be a virus or a marine biotoxin.''
Dr Madie compared the reported sub-antarctic pattern of symptoms with food poisoning: at first only the susceptible were found to be sick; the day after, everybody suffered.
``But it's a real puzzle,'' he said.
On Monday, a meeting is planned between fishing industry members, the Conservation Department, the Fisheries Ministry and research organisations.
Both the Fisheries Ministry and the Conservation Department said they were keeping a close watch on what was happening.