Wellington, Feb 9 - Massey University scientists searching for a possible cause of the mass death of sea lions south of mainland New Zealand are concentrating their efforts on finding a bacteria.
Hundreds of rare New Zealand sea lions, previously known as hooker's sea lions, have been found, mostly on Dundas Island in the Auckland Islands group, a breeding ground for the sea lions.
Massey University Cetacean Investigation Centre director Per Madie said a virus had been all but ruled out as a cause of the deaths.
Tissue samples cultivated in petrie dishes had produced a large number of bacteria, and tests could be completed this week, Mr Madie said.
The tests would not necessarily prove what the cause of the deaths were, and might only prove bacteria was also not responsible, he said.
``It could be a bacteria, though we haven't found one which could cause mass deaths yet. Even if we do, the only way we would know if it was responsible was if we put it into healthy sea lions.''
He said the eight-strong research team was feeling more pressure than usual in their efforts to complete the tests.
``It is a topic which most New Zealanders are very interested in, especially since it is `our sea lion' -- they are not found anywhere else in the world, and there are very few of them left.
``It almost takes the status of the kiwi, so it should be considered with some veneration.
``Luckily the students are not here at the moment. They're back in two weeks, and I sincerely hope to solve this problem by then.''
Tests to establish whether a marine biotoxin could have been responsible were being carried out at the Ruakura laboratories near Hamilton.
Ian Garthwaite, a scientist with the toxicology and food safety group at Ruakura, said today tests had so far been inconclusive, but that he should be able to confirm if any biotoxin was evident by Wednesday.
The sub-Antarctic Auckland Islands have been closed to tourists. Conservation Minister Nick Smith said the islands would be reopened when the situation had returned to normal.